* [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...]
@ 2023-07-01 3:24 Nathaniel Shead
2023-07-01 3:28 ` [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675] Nathaniel Shead
` (3 more replies)
0 siblings, 4 replies; 9+ messages in thread
From: Nathaniel Shead @ 2023-07-01 3:24 UTC (permalink / raw)
To: gcc-patches; +Cc: Patrick Palka
This is an update of the patch series at
https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614811.html
Changes since v2:
- Use a separate 'hash_set' to track expired variables instead of
adding a flag to 'lang_decl_base'.
- Use 'iloc_sentinel' to propagate location information down to
subexpressions instead of manually saving and falling back to a
parent expression's location.
- Update more tests with improved error location information.
Bootstrapped and regtested on x86_64-pc-linux-gnu.
---
Nathaniel Shead (3):
c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
c++: Improve constexpr error for dangling local variables
c++: Improve location information in constant evaluation
gcc/cp/constexpr.cc | 158 +++++++++++++++---
gcc/cp/semantics.cc | 5 +-
gcc/cp/typeck.cc | 5 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C | 10 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C | 8 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C | 8 +-
.../g++.dg/cpp0x/constexpr-delete2.C | 5 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C | 2 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C | 1 +
.../g++.dg/cpp0x/constexpr-recursion.C | 6 +-
gcc/testsuite/g++.dg/cpp0x/overflow1.C | 2 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C | 5 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C | 3 +-
.../g++.dg/cpp1y/constexpr-lifetime1.C | 14 ++
.../g++.dg/cpp1y/constexpr-lifetime2.C | 20 +++
.../g++.dg/cpp1y/constexpr-lifetime3.C | 13 ++
.../g++.dg/cpp1y/constexpr-lifetime4.C | 11 ++
.../g++.dg/cpp1y/constexpr-lifetime5.C | 11 ++
.../g++.dg/cpp1y/constexpr-tracking-const14.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const16.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const18.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const19.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const21.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const22.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const3.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const4.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const7.C | 3 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C | 4 +-
gcc/testsuite/g++.dg/cpp1y/pr68180.C | 4 +-
.../g++.dg/cpp1z/constexpr-lambda6.C | 4 +-
.../g++.dg/cpp1z/constexpr-lambda8.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/bit-cast11.C | 10 +-
gcc/testsuite/g++.dg/cpp2a/bit-cast12.C | 10 +-
gcc/testsuite/g++.dg/cpp2a/bit-cast14.C | 14 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C | 4 +-
.../g++.dg/cpp2a/constexpr-dynamic17.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C | 6 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C | 10 +-
gcc/testsuite/g++.dg/cpp2a/constinit10.C | 5 +-
.../g++.dg/cpp2a/is-corresponding-member4.C | 4 +-
gcc/testsuite/g++.dg/ext/constexpr-vla2.C | 4 +-
gcc/testsuite/g++.dg/ext/constexpr-vla3.C | 4 +-
gcc/testsuite/g++.dg/ubsan/pr63956.C | 23 +--
.../g++.dg/warn/Wreturn-local-addr-6.C | 3 -
.../25_algorithms/equal/constexpr_neg.cc | 7 +-
.../testsuite/26_numerics/gcd/105844.cc | 10 +-
.../testsuite/26_numerics/lcm/105844.cc | 14 +-
48 files changed, 330 insertions(+), 143 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
--
2.41.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
2023-07-01 3:24 [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Nathaniel Shead
@ 2023-07-01 3:28 ` Nathaniel Shead
2023-07-14 15:16 ` Jason Merrill
2023-07-01 3:30 ` [PATCH v3 2/3] c++: Improve constexpr error for dangling local variables Nathaniel Shead
` (2 subsequent siblings)
3 siblings, 1 reply; 9+ messages in thread
From: Nathaniel Shead @ 2023-07-01 3:28 UTC (permalink / raw)
To: gcc-patches; +Cc: Patrick Palka
This adds rudimentary lifetime tracking in C++ constexpr contexts,
allowing the compiler to report errors with using values after their
backing has gone out of scope. We don't yet handle other ways of
accessing values outside their lifetime (e.g. following explicit
destructor calls).
PR c++/96630
PR c++/98675
PR c++/70331
gcc/cp/ChangeLog:
* constexpr.cc (constexpr_global_ctx::remove_value): Mark value as
outside lifetime.
(find_expired_values): New function.
(outside_lifetime_error): New function.
(cxx_eval_call_expression): Don't cache calls that return references to
values outside their lifetime.
(cxx_eval_constant_expression): Add checks for out-of-lifetime values.
Forget local variables at end of bind expressions, and temporaries
after cleanup points.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-lifetime1.C: New test.
* g++.dg/cpp1y/constexpr-lifetime2.C: New test.
* g++.dg/cpp1y/constexpr-lifetime3.C: New test.
* g++.dg/cpp1y/constexpr-lifetime4.C: New test.
* g++.dg/cpp1y/constexpr-lifetime5.C: New test.
Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
gcc/cp/constexpr.cc | 112 ++++++++++++++----
.../g++.dg/cpp1y/constexpr-lifetime1.C | 13 ++
.../g++.dg/cpp1y/constexpr-lifetime2.C | 20 ++++
.../g++.dg/cpp1y/constexpr-lifetime3.C | 13 ++
.../g++.dg/cpp1y/constexpr-lifetime4.C | 11 ++
.../g++.dg/cpp1y/constexpr-lifetime5.C | 11 ++
6 files changed, 160 insertions(+), 20 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index cca0435bafc..bc59b4aab67 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -1165,6 +1165,8 @@ public:
hash_set<tree> *modifiable;
/* Number of heap VAR_DECL deallocations. */
unsigned heap_dealloc_count;
+ /* Values that are not within their lifetime. */
+ hash_set<tree> outside_lifetime;
/* Constructor. */
constexpr_global_ctx ()
: constexpr_ops_count (0), cleanups (NULL), modifiable (nullptr),
@@ -1188,7 +1190,12 @@ public:
if (!already_in_map && modifiable)
modifiable->add (t);
}
- void remove_value (tree t) { values.remove (t); }
+ void remove_value (tree t)
+ {
+ if (DECL_P (t))
+ outside_lifetime.add (t);
+ values.remove (t);
+ }
};
/* Helper class for constexpr_global_ctx. In some cases we want to avoid
@@ -2509,6 +2516,22 @@ cxx_eval_dynamic_cast_fn (const constexpr_ctx *ctx, tree call,
return cp_build_addr_expr (obj, complain);
}
+/* Look for expired values in the expression *TP, called through
+ cp_walk_tree. DATA is ctx->global->outside_lifetime. */
+
+static tree
+find_expired_values (tree *tp, int *walk_subtrees, void *data)
+{
+ hash_set<tree> *outside_lifetime = (hash_set<tree> *) data;
+
+ if (TYPE_P (*tp))
+ *walk_subtrees = 0;
+ else if (outside_lifetime->contains (*tp))
+ return *tp;
+
+ return NULL_TREE;
+}
+
/* Data structure used by replace_decl and replace_decl_r. */
struct replace_decl_data
@@ -3160,10 +3183,7 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
for (tree save_expr : save_exprs)
ctx->global->remove_value (save_expr);
- /* Remove the parms/result from the values map. Is it worth
- bothering to do this when the map itself is only live for
- one constexpr evaluation? If so, maybe also clear out
- other vars from call, maybe in BIND_EXPR handling? */
+ /* Remove the parms/result from the values map. */
ctx->global->remove_value (res);
for (tree parm = parms; parm; parm = TREE_CHAIN (parm))
ctx->global->remove_value (parm);
@@ -3210,13 +3230,20 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
cacheable = false;
}
- /* Rewrite all occurrences of the function's RESULT_DECL with the
- current object under construction. */
- if (!*non_constant_p && ctx->object
- && CLASS_TYPE_P (TREE_TYPE (res))
- && !is_empty_class (TREE_TYPE (res)))
- if (replace_decl (&result, res, ctx->object))
- cacheable = false;
+ /* Also don't cache a call if we return a pointer to an expired
+ value. */
+ if (cacheable && (cp_walk_tree_without_duplicates
+ (&result, find_expired_values,
+ &ctx->global->outside_lifetime)))
+ cacheable = false;
+
+ /* Rewrite all occurrences of the function's RESULT_DECL with the
+ current object under construction. */
+ if (!*non_constant_p && ctx->object
+ && CLASS_TYPE_P (TREE_TYPE (res))
+ && !is_empty_class (TREE_TYPE (res)))
+ if (replace_decl (&result, res, ctx->object))
+ cacheable = false;
}
else
/* Couldn't get a function copy to evaluate. */
@@ -5687,6 +5714,25 @@ cxx_eval_indirect_ref (const constexpr_ctx *ctx, tree t,
return r;
}
+/* Complain about R, a DECL that is accessed outside its lifetime. */
+
+static void
+outside_lifetime_error (location_t loc, tree r)
+{
+ if (DECL_NAME (r) == heap_deleted_identifier)
+ {
+ /* Provide a more accurate message for deleted variables. */
+ error_at (loc, "use of allocated storage after deallocation "
+ "in a constant expression");
+ inform (DECL_SOURCE_LOCATION (r), "allocated here");
+ }
+ else
+ {
+ error_at (loc, "accessing object outside its lifetime");
+ inform (DECL_SOURCE_LOCATION (r), "declared here");
+ }
+}
+
/* Complain about R, a VAR_DECL, not being usable in a constant expression.
FUNDEF_P is true if we're checking a constexpr function body.
Shared between potential_constant_expression and
@@ -7054,6 +7100,13 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
r = build_constructor (TREE_TYPE (t), NULL);
TREE_CONSTANT (r) = true;
}
+ else if (ctx->global->outside_lifetime.contains (t))
+ {
+ if (!ctx->quiet)
+ outside_lifetime_error (loc, t);
+ *non_constant_p = true;
+ break;
+ }
else if (ctx->strict)
r = decl_really_constant_value (t, /*unshare_p=*/false);
else
@@ -7085,7 +7138,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
case PARM_DECL:
if (lval && !TYPE_REF_P (TREE_TYPE (t)))
/* glvalue use. */;
- else if (tree v = ctx->global->get_value (r))
+ else if (tree v = ctx->global->get_value (t))
r = v;
else if (lval)
/* Defer in case this is only used for its type. */;
@@ -7099,7 +7152,12 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
else
{
if (!ctx->quiet)
- error ("%qE is not a constant expression", t);
+ {
+ if (ctx->global->outside_lifetime.contains (t))
+ outside_lifetime_error (loc, t);
+ else
+ error_at (loc, "%qE is not a constant expression", t);
+ }
*non_constant_p = true;
}
break;
@@ -7328,17 +7386,28 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
auto_vec<tree, 2> cleanups;
vec<tree> *prev_cleanups = ctx->global->cleanups;
ctx->global->cleanups = &cleanups;
- r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
+
+ auto_vec<tree, 10> save_exprs;
+ constexpr_ctx new_ctx = *ctx;
+ new_ctx.save_exprs = &save_exprs;
+
+ r = cxx_eval_constant_expression (&new_ctx, TREE_OPERAND (t, 0),
lval,
non_constant_p, overflow_p,
jump_target);
+
ctx->global->cleanups = prev_cleanups;
unsigned int i;
tree cleanup;
/* Evaluate the cleanups. */
FOR_EACH_VEC_ELT_REVERSE (cleanups, i, cleanup)
- cxx_eval_constant_expression (ctx, cleanup, vc_discard,
+ cxx_eval_constant_expression (&new_ctx, cleanup, vc_discard,
non_constant_p, overflow_p);
+
+ /* Forget SAVE_EXPRs and TARGET_EXPRs created by this
+ full-expression. */
+ for (tree save_expr : save_exprs)
+ ctx->global->remove_value (save_expr);
}
break;
@@ -7855,10 +7924,13 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
non_constant_p, overflow_p, jump_target);
case BIND_EXPR:
- return cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (t),
- lval,
- non_constant_p, overflow_p,
- jump_target);
+ r = cxx_eval_constant_expression (ctx, BIND_EXPR_BODY (t),
+ lval,
+ non_constant_p, overflow_p,
+ jump_target);
+ for (tree decl = BIND_EXPR_VARS (t); decl; decl = DECL_CHAIN (decl))
+ ctx->global->remove_value (decl);
+ return r;
case PREINCREMENT_EXPR:
case POSTINCREMENT_EXPR:
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
new file mode 100644
index 00000000000..43aa7c974c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
@@ -0,0 +1,13 @@
+// PR c++/96630
+// { dg-do compile { target c++14 } }
+
+struct S {
+ int x = 0;
+ constexpr const int& get() const { return x; }
+};
+
+constexpr const int& test() {
+ auto local = S{}; // { dg-message "note: declared here" }
+ return local.get();
+}
+constexpr int x = test(); // { dg-error "accessing object outside its lifetime" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
new file mode 100644
index 00000000000..22cd919fcda
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
@@ -0,0 +1,20 @@
+// PR c++/98675
+// { dg-do compile { target c++14 } }
+
+struct S {
+ int x = 0;
+ constexpr const int& get() const { return x; }
+};
+
+constexpr int error() {
+ const auto& local = S{}.get(); // { dg-message "note: declared here" }
+ return local;
+}
+constexpr int x = error(); // { dg-error "accessing object outside its lifetime" }
+
+constexpr int ok() {
+ // temporary should only be destroyed after end of full-expression
+ auto local = S{}.get();
+ return local;
+}
+constexpr int y = ok();
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
new file mode 100644
index 00000000000..6329f8cf6c6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
@@ -0,0 +1,13 @@
+// PR c++/70331
+// { dg-do compile { target c++14 } }
+
+constexpr int f(int i) {
+ int *p = &i;
+ if (i == 0) {
+ int j = 123; // { dg-message "note: declared here" }
+ p = &j;
+ }
+ return *p;
+}
+
+constexpr int i = f(0); // { dg-error "accessing object outside its lifetime" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
new file mode 100644
index 00000000000..181a1201663
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++14 } }
+
+constexpr const double& test() {
+ const double& local = 3.0; // { dg-message "note: declared here" }
+ return local;
+}
+
+static_assert(test() == 3.0, ""); // { dg-error "constant|accessing object outside its lifetime" }
+
+// no deference, shouldn't error
+static_assert((test(), true), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
new file mode 100644
index 00000000000..a4bc71d890a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++14 } }
+// { dg-options "-Wno-return-local-addr" }
+
+constexpr const int& id(int x) { return x; }
+
+constexpr bool test() {
+ const int& y = id(3);
+ return y == 3;
+}
+
+constexpr bool x = test(); // { dg-error "" }
--
2.41.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v3 2/3] c++: Improve constexpr error for dangling local variables
2023-07-01 3:24 [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Nathaniel Shead
2023-07-01 3:28 ` [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675] Nathaniel Shead
@ 2023-07-01 3:30 ` Nathaniel Shead
2023-07-01 3:30 ` [PATCH v3 3/3] c++: Improve location information in constant evaluation Nathaniel Shead
2023-07-10 19:23 ` [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Patrick Palka
3 siblings, 0 replies; 9+ messages in thread
From: Nathaniel Shead @ 2023-07-01 3:30 UTC (permalink / raw)
To: gcc-patches; +Cc: Patrick Palka
Currently, when typeck discovers that a return statement will refer to a
local variable it rewrites to return a null pointer. This causes the
error messages for using the return value in a constant expression to be
unhelpful, especially for reference return values.
This patch removes this "optimisation". Relying on this raises a warning
by default and causes UB anyway, so there should be no issue in doing
so. We also suppress additional warnings from later passes that detect
this as a dangling pointer, since we've already indicated this anyway.
gcc/cp/ChangeLog:
* semantics.cc (finish_return_stmt): Suppress dangling pointer
reporting on return statement if already reported.
* typeck.cc (check_return_expr): Don't set return expression to
zero for dangling addresses.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-lifetime5.C: Test reported message is
correct.
* g++.dg/warn/Wreturn-local-addr-6.C: Remove check for return
value optimisation.
Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
gcc/cp/semantics.cc | 5 ++++-
gcc/cp/typeck.cc | 5 +++--
gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C | 4 ++--
gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C | 3 ---
4 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8fb47fd179e..107407de513 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -1260,7 +1260,10 @@ finish_return_stmt (tree expr)
r = build_stmt (input_location, RETURN_EXPR, expr);
if (no_warning)
- suppress_warning (r, OPT_Wreturn_type);
+ {
+ suppress_warning (r, OPT_Wreturn_type);
+ suppress_warning (r, OPT_Wdangling_pointer_);
+ }
r = maybe_cleanup_point_expr_void (r);
r = add_stmt (r);
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 859b133a18d..47233b3b717 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -11273,8 +11273,9 @@ check_return_expr (tree retval, bool *no_warning)
else if (!processing_template_decl
&& maybe_warn_about_returning_address_of_local (retval, loc)
&& INDIRECT_TYPE_P (valtype))
- retval = build2 (COMPOUND_EXPR, TREE_TYPE (retval), retval,
- build_zero_cst (TREE_TYPE (retval)));
+ /* Suppress the Wdangling-pointer warning in the return statement
+ that would otherwise occur. */
+ *no_warning = true;
}
/* A naive attempt to reduce the number of -Wdangling-reference false
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
index a4bc71d890a..ad3ef579f63 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
@@ -1,11 +1,11 @@
// { dg-do compile { target c++14 } }
// { dg-options "-Wno-return-local-addr" }
-constexpr const int& id(int x) { return x; }
+constexpr const int& id(int x) { return x; } // { dg-message "note: declared here" }
constexpr bool test() {
const int& y = id(3);
return y == 3;
}
-constexpr bool x = test(); // { dg-error "" }
+constexpr bool x = test(); // { dg-error "accessing object outside its lifetime" }
diff --git a/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
index fae8b7e766f..ec8e241d83e 100644
--- a/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
+++ b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
@@ -24,6 +24,3 @@ return_addr_local_as_intref (void)
return (const intptr_t&)a; // { dg-warning "\\\[-Wreturn-local-addr]" } */
}
-
-/* Verify that the return value has been replaced with zero:
- { dg-final { scan-tree-dump-times "return 0;" 2 "optimized" } } */
--
2.41.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v3 3/3] c++: Improve location information in constant evaluation
2023-07-01 3:24 [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Nathaniel Shead
2023-07-01 3:28 ` [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675] Nathaniel Shead
2023-07-01 3:30 ` [PATCH v3 2/3] c++: Improve constexpr error for dangling local variables Nathaniel Shead
@ 2023-07-01 3:30 ` Nathaniel Shead
2023-07-10 19:23 ` [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Patrick Palka
3 siblings, 0 replies; 9+ messages in thread
From: Nathaniel Shead @ 2023-07-01 3:30 UTC (permalink / raw)
To: gcc-patches; +Cc: Patrick Palka
This patch updates 'input_location' during constant evaluation to ensure
that errors in subexpressions that lack location information still
provide accurate diagnostics.
By itself this change causes some small regressions in diagnostic
quality for circumstances where errors used 'input_location' but the
location of the parent subexpression doesn't make sense, so this patch
also includes a couple of other small diagnostic improvements to improve
the most egregious cases.
gcc/cp/ChangeLog:
* constexpr.cc (modifying_const_object_error): Find the source
location of the const object's declaration.
(cxx_eval_store_expression): Fall back to the location of the
target object when evaluating initialiser.
(cxx_eval_constant_expression): Update input_location to the location
of the currently evaluated expression.
libstdc++-v3/ChangeLog:
* testsuite/25_algorithms/equal/constexpr_neg.cc: Update diagnostic
locations.
* testsuite/26_numerics/gcd/105844.cc: Likewise.
* testsuite/26_numerics/lcm/105844.cc: Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-48089.C: Update diagnostic locations.
* g++.dg/cpp0x/constexpr-70323.C: Likewise.
* g++.dg/cpp0x/constexpr-70323a.C: Likewise.
* g++.dg/cpp0x/constexpr-delete2.C: Likewise.
* g++.dg/cpp0x/constexpr-diag3.C: Likewise.
* g++.dg/cpp0x/constexpr-ice20.C: Likewise.
* g++.dg/cpp0x/constexpr-recursion.C: Likewise.
* g++.dg/cpp0x/overflow1.C: Likewise.
* g++.dg/cpp1y/constexpr-89285.C: Likewise.
* g++.dg/cpp1y/constexpr-89481.C: Likewise.
* g++.dg/cpp1y/constexpr-lifetime1.C: Likewise.
* g++.dg/cpp1y/constexpr-lifetime2.C: Likewise.
* g++.dg/cpp1y/constexpr-lifetime3.C: Likewise.
* g++.dg/cpp1y/constexpr-lifetime4.C: Likewise.
* g++.dg/cpp1y/constexpr-lifetime5.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const14.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const16.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const18.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const19.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const21.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const22.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const3.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const4.C: Likewise.
* g++.dg/cpp1y/constexpr-tracking-const7.C: Likewise.
* g++.dg/cpp1y/constexpr-union5.C: Likewise.
* g++.dg/cpp1y/pr68180.C: Likewise.
* g++.dg/cpp1z/constexpr-lambda6.C: Likewise.
* g++.dg/cpp1z/constexpr-lambda8.C: Likewise.
* g++.dg/cpp2a/bit-cast11.C: Likewise.
* g++.dg/cpp2a/bit-cast12.C: Likewise.
* g++.dg/cpp2a/bit-cast14.C: Likewise.
* g++.dg/cpp2a/constexpr-98122.C: Likewise.
* g++.dg/cpp2a/constexpr-dynamic17.C: Likewise.
* g++.dg/cpp2a/constexpr-init1.C: Likewise.
* g++.dg/cpp2a/constexpr-new12.C: Likewise.
* g++.dg/cpp2a/constexpr-new3.C: Likewise.
* g++.dg/cpp2a/constinit10.C: Likewise.
* g++.dg/cpp2a/is-corresponding-member4.C: Likewise.
* g++.dg/ext/constexpr-vla2.C: Likewise.
* g++.dg/ext/constexpr-vla3.C: Likewise.
* g++.dg/ubsan/pr63956.C: Likewise.
Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
gcc/cp/constexpr.cc | 46 ++++++++++++++++++-
gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C | 10 ++--
gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C | 8 ++--
gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C | 8 ++--
.../g++.dg/cpp0x/constexpr-delete2.C | 5 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C | 2 +-
gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C | 1 +
.../g++.dg/cpp0x/constexpr-recursion.C | 6 +--
gcc/testsuite/g++.dg/cpp0x/overflow1.C | 2 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C | 5 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C | 3 +-
.../g++.dg/cpp1y/constexpr-lifetime1.C | 1 +
.../g++.dg/cpp1y/constexpr-lifetime2.C | 4 +-
.../g++.dg/cpp1y/constexpr-lifetime3.C | 4 +-
.../g++.dg/cpp1y/constexpr-lifetime4.C | 2 +-
.../g++.dg/cpp1y/constexpr-lifetime5.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const14.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const16.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const18.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const19.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const21.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const22.C | 4 +-
.../g++.dg/cpp1y/constexpr-tracking-const3.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const4.C | 3 +-
.../g++.dg/cpp1y/constexpr-tracking-const7.C | 3 +-
gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C | 4 +-
gcc/testsuite/g++.dg/cpp1y/pr68180.C | 4 +-
.../g++.dg/cpp1z/constexpr-lambda6.C | 4 +-
.../g++.dg/cpp1z/constexpr-lambda8.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/bit-cast11.C | 10 ++--
gcc/testsuite/g++.dg/cpp2a/bit-cast12.C | 10 ++--
gcc/testsuite/g++.dg/cpp2a/bit-cast14.C | 14 +++---
gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C | 4 +-
.../g++.dg/cpp2a/constexpr-dynamic17.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C | 5 +-
gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C | 6 +--
gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C | 10 ++--
gcc/testsuite/g++.dg/cpp2a/constinit10.C | 5 +-
.../g++.dg/cpp2a/is-corresponding-member4.C | 4 +-
gcc/testsuite/g++.dg/ext/constexpr-vla2.C | 4 +-
gcc/testsuite/g++.dg/ext/constexpr-vla3.C | 4 +-
gcc/testsuite/g++.dg/ubsan/pr63956.C | 23 +++++-----
.../25_algorithms/equal/constexpr_neg.cc | 7 +--
.../testsuite/26_numerics/gcd/105844.cc | 10 ++--
.../testsuite/26_numerics/lcm/105844.cc | 14 +++---
45 files changed, 170 insertions(+), 124 deletions(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index bc59b4aab67..0b8697b4a85 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -2165,7 +2165,33 @@ modifying_const_object_error (tree expr, tree obj)
auto_diagnostic_group d;
error_at (loc, "modifying a const object %qE is not allowed in "
"a constant expression", TREE_OPERAND (expr, 0));
- inform (location_of (obj), "originally declared %<const%> here");
+
+ /* Find the underlying object that was declared as const. */
+ location_t decl_loc = UNKNOWN_LOCATION;
+ for (tree probe = obj; decl_loc == UNKNOWN_LOCATION; )
+ switch (TREE_CODE (probe))
+ {
+ case BIT_FIELD_REF:
+ case COMPONENT_REF:
+ {
+ tree elt = TREE_OPERAND (probe, 1);
+ if (CP_TYPE_CONST_P (TREE_TYPE (elt)))
+ decl_loc = DECL_SOURCE_LOCATION (elt);
+ probe = TREE_OPERAND (probe, 0);
+ }
+ break;
+
+ case ARRAY_REF:
+ case REALPART_EXPR:
+ case IMAGPART_EXPR:
+ probe = TREE_OPERAND (probe, 0);
+ break;
+
+ default:
+ decl_loc = location_of (probe);
+ break;
+ }
+ inform (decl_loc, "originally declared %<const%> here");
}
/* Return true if FNDECL is a replaceable global allocation function that
@@ -6286,6 +6312,21 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t,
if (TREE_CODE (init) == TARGET_EXPR)
if (tree tinit = TARGET_EXPR_INITIAL (init))
init = tinit;
+
+ /* Improve error messages for initialisers when the initialising
+ expression has no location information by pointing to the decl
+ that is getting initialised. */
+ location_t target_loc = cp_expr_loc_or_input_loc (init);
+ if (!EXPR_HAS_LOCATION (init))
+ {
+ if (DECL_P (target))
+ target_loc = DECL_SOURCE_LOCATION (target);
+ else if (TREE_CODE (target) == COMPONENT_REF
+ || TREE_CODE (target) == BIT_FIELD_REF)
+ target_loc = DECL_SOURCE_LOCATION (TREE_OPERAND (target, 1));
+ }
+ iloc_sentinel sentinel = target_loc;
+
init = cxx_eval_constant_expression (&new_ctx, init, vc_prvalue,
non_constant_p, overflow_p);
/* The hash table might have moved since the get earlier, and the
@@ -6986,7 +7027,10 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
return t;
}
+ /* Change the input location to the currently processed expression for
+ better error messages when a subexpression has no location. */
location_t loc = cp_expr_loc_or_input_loc (t);
+ iloc_sentinel sentinel (loc);
STRIP_ANY_LOCATION_WRAPPER (t);
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
index 4574eb83ff7..11630f26ffe 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C
@@ -10,11 +10,11 @@
// R() is well-formed because i is initialized before j.
struct s {
- constexpr s() : v(v) { }
+ constexpr s() : v(v) { } // { dg-error "accessing uninitialized member" }
int v;
};
-constexpr s bang; // { dg-error "|" }
+constexpr s bang; // { dg-message "in .constexpr. expansion" }
struct R {
int i,j;
@@ -26,14 +26,14 @@ constexpr R r; // { dg-bogus "" }
// Ill-formed (no diagnostic required)
struct T {
int i;
- constexpr int f() { return i; }
+ constexpr int f() { return i; } // { dg-error "accessing uninitialized member" }
constexpr T(): i(0) { }
- constexpr T(const T& t) : i(f()) { } // { dg-message "" }
+ constexpr T(const T& t) : i(f()) { } // { dg-message "in .constexpr. expansion" }
};
constexpr T t1;
// Ill-formed (diagnostic required)
-constexpr T t2(t1); // { dg-message "" }
+constexpr T t2(t1); // { dg-message "in .constexpr. expansion" }
// Well-formed
struct U {
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
index 272a225d967..bfb185f2fb5 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C
@@ -1,10 +1,10 @@
// PR c++/70323
// { dg-do compile { target c++11 } }
-constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }
-constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }
+constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; } // { dg-error "overflow in constant expression" }
+constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; } // { dg-error "overflow in constant expression" }
-constexpr bool i0_0 = overflow_if_0 (0); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr bool i0_0 = overflow_if_0 (0); // { dg-message "in .constexpr. expansion of " }
constexpr bool i0_1 = overflow_if_0 (1);
constexpr bool i1_0 = overflow_if_1 (0);
-constexpr bool i1_1 = overflow_if_1 (1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr bool i1_1 = overflow_if_1 (1); // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
index 1990ab6be2d..b5ed581e1c8 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C
@@ -2,10 +2,10 @@
// { dg-do compile { target c++11 } }
// { dg-options "-Wall" }
-constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; }
-constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; }
+constexpr int overflow_if_0 (int i) { return __INT_MAX__ + !i; } // { dg-error "overflow in constant expression" }
+constexpr int overflow_if_1 (int i) { return __INT_MAX__ + i; } // { dg-error "overflow in constant expression" }
-constexpr bool i0_0 = overflow_if_0 (0); // { dg-error "overflow in constant expression|in .constexpr. expansion of" }
+constexpr bool i0_0 = overflow_if_0 (0); // { dg-message "in .constexpr. expansion of" }
constexpr bool i0_1 = overflow_if_0 (1);
constexpr bool i1_0 = overflow_if_1 (0);
-constexpr bool i1_1 = overflow_if_1 (1); // { dg-error "overflow in constant expression|in .constexpr. expansion of" }
+constexpr bool i1_1 = overflow_if_1 (1); // { dg-message "in .constexpr. expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
index 999f9b7851e..f2b6df2509c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-delete2.C
@@ -6,8 +6,9 @@ constexpr int f(int i) { return i; }
constexpr int g(A* ap)
{
return f((delete[] ap, 42)); // { dg-message "" "" { target c++17_down } }
+ // { dg-error "" "" { target c++2a } .-1 }
}
A a;
-constexpr int i = g(&a); // { dg-error "" }
- // { dg-message "in 'constexpr' expansion of" "" { target c++2a } .-1 }
+constexpr int i = g(&a); // { dg-error "" "" { target c++17_down } }
+ // { dg-message "in 'constexpr' expansion of" "" { target c++2a } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
index 5eedf42ba36..50c676c56cd 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C
@@ -16,7 +16,7 @@ int main()
struct complex // { dg-message "no .constexpr. constructor" "" { target { ! implicit_constexpr } } }
{
complex(double r, double i) : re(r), im(i) { }
- constexpr double real() const { return re; } // { dg-error "not a literal type" "" { target c++11_only } }
+ constexpr double real() const { return re; } // { dg-error "not a literal type|not usable in a constant expression" "" { target { ! implicit_constexpr } } }
double imag() const { return im; }
private:
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
index e2d4853a284..43fa9a03c14 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C
@@ -3,5 +3,6 @@
typedef bool (*Function)(int);
constexpr bool check(int x, Function p) { return p(x); } // { dg-message "in .constexpr. expansion of" }
+// { dg-error "not a constant expression" "" { target *-*-* } .-1 }
static_assert(check(2, check), ""); // { dg-error "conversion|constant|in .constexpr. expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
index 8c4201e1ec2..b00f8794d4c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-recursion.C
@@ -1,6 +1,6 @@
// Test that we catch excessive recursion.
// { dg-do compile { target c++11 } }
// { dg-options "-fconstexpr-depth=5" }
-// { dg-prune-output "in constexpr expansion" }
-constexpr int f (int i) { return f (i-1); } // { dg-message "in .constexpr. expansion of " }
-constexpr int i = f(42); // { dg-error ".constexpr. evaluation depth|in .constexpr. expansion of " }
+// { dg-prune-output "in .constexpr. expansion" }
+constexpr int f (int i) { return f (i-1); } // { dg-error ".constexpr. evaluation depth" }
+constexpr int i = f(42);
diff --git a/gcc/testsuite/g++.dg/cpp0x/overflow1.C b/gcc/testsuite/g++.dg/cpp0x/overflow1.C
index b8591b4af41..e295355c88f 100644
--- a/gcc/testsuite/g++.dg/cpp0x/overflow1.C
+++ b/gcc/testsuite/g++.dg/cpp0x/overflow1.C
@@ -4,7 +4,7 @@ template <long long i>
struct Fib
{
static const long long value // { dg-error "overflow" }
- = Fib<i-1>::value + Fib<i-2>::value;
+ = Fib<i-1>::value + Fib<i-2>::value; // { dg-error "overflow" }
};
template <>
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
index fe0b8570ca2..d09df091fdb 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C
@@ -14,7 +14,8 @@ struct B {
}
};
struct C : A {
- B bar {this};
+ B bar {this}; // { dg-error "" "" { target c++14_down } }
};
-constexpr C foo {}; // { dg-message "" }
+// error path changes in C++17 due to `C` becoming an aggregate
+constexpr C foo {}; // { dg-error "" "" { target c++17 } }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
index 8ac4ef0fd36..6f8f6a8038e 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C
@@ -6,7 +6,7 @@ foo ()
{
union U { long long a; int b[2]; } u { 5LL };
u.b[1] = 4; // { dg-error "change of the active member of a union from" "" { target c++17_down } }
- return u.b[0];
+ return u.b[0]; // { dg-error "accessing uninitialized array element" "" { target c++2a } }
}
constexpr int
@@ -19,6 +19,5 @@ bar ()
static_assert (foo () == 0, ""); // { dg-error "non-constant condition for static assertion" }
// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
- // { dg-error "accessing uninitialized array element" "" { target c++2a } .-2 }
static_assert (bar () == 4, ""); // { dg-error "non-constant condition for static assertion" "" { target c++17_down } }
// { dg-message "in 'constexpr' expansion of" "" { target c++17_down } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
index 43aa7c974c1..f79f1611d5f 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
@@ -11,3 +11,4 @@ constexpr const int& test() {
return local.get();
}
constexpr int x = test(); // { dg-error "accessing object outside its lifetime" }
+
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
index 22cd919fcda..2f5ae8db6d5 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
@@ -8,9 +8,9 @@ struct S {
constexpr int error() {
const auto& local = S{}.get(); // { dg-message "note: declared here" }
- return local;
+ return local; // { dg-error "accessing object outside its lifetime" }
}
-constexpr int x = error(); // { dg-error "accessing object outside its lifetime" }
+constexpr int x = error(); // { dg-message "in .constexpr. expansion" }
constexpr int ok() {
// temporary should only be destroyed after end of full-expression
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
index 6329f8cf6c6..53785521d05 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
@@ -7,7 +7,7 @@ constexpr int f(int i) {
int j = 123; // { dg-message "note: declared here" }
p = &j;
}
- return *p;
+ return *p; // { dg-error "accessing object outside its lifetime" }
}
-constexpr int i = f(0); // { dg-error "accessing object outside its lifetime" }
+constexpr int i = f(0); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
index 181a1201663..4302da1eddc 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
@@ -5,7 +5,7 @@ constexpr const double& test() {
return local;
}
-static_assert(test() == 3.0, ""); // { dg-error "constant|accessing object outside its lifetime" }
+static_assert(test() == 3.0, ""); // { dg-error "non-constant condition|accessing object outside its lifetime" }
// no deference, shouldn't error
static_assert((test(), true), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
index ad3ef579f63..a12920c8fba 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
@@ -5,7 +5,7 @@ constexpr const int& id(int x) { return x; } // { dg-message "note: declared he
constexpr bool test() {
const int& y = id(3);
- return y == 3;
+ return y == 3; // { dg-error "accessing object outside its lifetime" }
}
-constexpr bool x = test(); // { dg-error "accessing object outside its lifetime" }
+constexpr bool x = test(); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
index 45c4fcf50be..0c77dd4934d 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const14.C
@@ -14,7 +14,7 @@ struct C {
struct A {
int r;
- const C c;
+ const C c; // { dg-message "originally declared" }
constexpr A() : r(11) { r = 14; const_cast<C &>(c).n = 42; } // { dg-error "modifying a const object" }
};
@@ -34,5 +34,4 @@ struct B {
};
constexpr B b(false); // { dg-message "in .constexpr. expansion of" }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
static_assert(b.e.d.a.c.n == 2, ""); // { dg-error "non-constant condition" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
index 5a5b92bc8cc..b5ccf3a4ea5 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const16.C
@@ -7,7 +7,7 @@ constexpr int& impl(const int (&array)[10], int index) {
struct A {
constexpr int& operator[](int i) { return impl(elems, i); }
- const int elems[10];
+ const int elems[10]; // { dg-message "originally declared" }
};
constexpr bool
@@ -19,4 +19,3 @@ f()
}
constexpr bool b = f(); // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
index 11a680468c2..278628c121b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const18.C
@@ -13,11 +13,11 @@ struct array
template <typename T>
struct S {
using U = array<T, 4>;
- const U m;
+ const U m; // { dg-message "originally declared" }
constexpr S(int) : m{}
{
const_cast<int &>(const_cast<const U &>(m)[0]) = 42; // { dg-error "modifying a const object" }
}
};
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
index c31222ffcdd..2d18c94537b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const19.C
@@ -7,7 +7,7 @@ template <typename E, size_t N>
struct array
{
constexpr const E &operator[](size_t n) const noexcept { return elems[n]; }
- const E elems[N];
+ const E elems[N]; // { dg-message "originally declared" }
};
template <typename T>
@@ -20,4 +20,4 @@ struct S {
}
};
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
index 0b16193398e..d3bbcb116a6 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const21.C
@@ -18,11 +18,11 @@ struct array2 {
template <typename T>
struct S {
using U = array2<T, 4>;
- const U m;
+ const U m; // { dg-message "originally declared" }
constexpr S(int) : m{}
{
const_cast<int &>(m.a[0]) = 42; // { dg-error "modifying a const object" }
}
};
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
index 216cf1607a4..27522f86dbd 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const22.C
@@ -7,11 +7,11 @@ struct X {
template <typename T>
struct S {
- const X x;
+ const X x; // { dg-message "originally declared" }
constexpr S(int) : x{}
{
const_cast<X&>(x).i = 19; // { dg-error "modifying a const object" }
}
};
-constexpr S<int> p = { 10 }; // { dg-message "originally declared" }
+constexpr S<int> p = { 10 };
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
index 6853775c1e2..fc88dd05eef 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const3.C
@@ -7,7 +7,7 @@ struct A {
};
struct B {
- const A a;
+ const A a; // { dg-message "originally declared" }
constexpr B(bool b) {
if (b)
const_cast<A &>(a).n = 3; // { dg-error "modifying a const object" }
@@ -18,5 +18,4 @@ constexpr B b(false);
static_assert(b.a.n == 2, "");
constexpr B b2(true); // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
static_assert((b2.a.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
index 8263a7cc505..27fede152c7 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const4.C
@@ -2,7 +2,7 @@
// { dg-do compile { target c++14 } }
struct A {
- const int n;
+ const int n; // { dg-message "originally declared" }
constexpr A() : n(1) { }
};
struct B {
@@ -13,5 +13,4 @@ struct B {
}
};
constexpr B b; // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
static_assert((b.a.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
index 922e8ff126f..bea14b05602 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-tracking-const7.C
@@ -3,7 +3,7 @@
struct D { int n; };
-struct C { const D d; };
+struct C { const D d; }; // { dg-message "originally declared" }
struct A {
C c;
@@ -19,5 +19,4 @@ struct B {
};
constexpr B b{}; // { dg-message "in .constexpr. expansion of " }
-// { dg-message "originally declared" "" { target *-*-* } .-1 }
static_assert((b.a.c.d.n, 1), "");
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
index 55fe9fa2f0b..3d76345d564 100644
--- a/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C
@@ -8,8 +8,8 @@ union U {
};
constexpr int foo(U *up) {
- up->a++;
+ up->a++; // { dg-error "accessing uninitialized member" }
return {42};
}
-extern constexpr U u = {}; // { dg-error "accessing uninitialized member" }
+extern constexpr U u = {}; // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr68180.C b/gcc/testsuite/g++.dg/cpp1y/pr68180.C
index 9e6e5e984f9..8de1ef3936b 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr68180.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr68180.C
@@ -6,11 +6,11 @@ typedef float __attribute__( ( vector_size( 16 ) ) ) float32x4_t;
constexpr float32x4_t fill(float x) {
float32x4_t v{0};
constexpr auto vs = sizeof(v)/sizeof(v[0]);
- for (auto i=0U; i<vs; ++i) v[i]=i;
+ for (auto i=0U; i<vs; ++i) v[i]=i; // { dg-error "not a constant" }
return v+x;
}
float32x4_t foo(float32x4_t x) {
- constexpr float32x4_t v = fill(1.f); // { dg-error "not a constant||in .constexpr. expansion of " }
+ constexpr float32x4_t v = fill(1.f); // { dg-message "in .constexpr. expansion of " }
return x+v;
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
index 214d3821299..c46c2d4c7fe 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda6.C
@@ -1,7 +1,7 @@
// Testcase from P0170R1
// { dg-do compile { target c++17 } }
-auto monoid = [](auto v) { return [=] { return v; }; };
+auto monoid = [](auto v) { return [=] { return v; }; }; // { dg-error "not usable in a constant expression" }
auto add = [](auto m1) constexpr {
auto ret = m1();
return [=](auto m2) mutable {
@@ -22,7 +22,7 @@ int main()
// member function call operator can not perform an lvalue-to-rvalue conversion
// on one of its subobjects (that represents its capture) in a constant
// expression.
- auto two = monoid(2);
+ auto two = monoid(2); // { dg-message "not declared .constexpr." }
if (!(two() == 2)) __builtin_abort(); // OK, not a constant expression.
static_assert(add(one)(one)() == two()); // { dg-error "|in .constexpr. expansion of " } two() is not a constant expression
static_assert(add(one)(one)() == monoid(2)()); // OK
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
index 84be68ab7f0..82351ff0c54 100644
--- a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda8.C
@@ -4,11 +4,14 @@
auto Fwd = [](int (*fp)(int), auto a) { return fp(a); };
auto C = [](auto a) { return a; };
static_assert( Fwd(C ,3) == 3); // OK
+
// No specialization of the function call operator template can be constexpr
// (because of the local static).
auto NC = [](auto a) { static int s; return a; }; // { dg-error "static" }
-// { dg-message "operator int" "" { target *-*-* } .+1 }
+// { dg-error "called in a constant expression" "" { target *-*-* } .-1 }
+
static_assert( Fwd(NC ,3) == 3); // { dg-error "" }
+// { dg-message "operator int" "" { target *-*-* } .-1 }
// We look for the string "operator int" to check that we aren't trying to do
// template pretty-printing in an expression; that gets incredibly unwieldy
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
index a3eb31bc6c7..760c9ca40b4 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast11.C
@@ -28,7 +28,7 @@ f3 ()
{
T t = { 1, 2 };
S s = __builtin_bit_cast (S, t);
- return s.a[1] == 0;
+ return s.a[1] == 0; // { dg-error "accessing uninitialized array element" }
}
constexpr bool
@@ -52,12 +52,12 @@ f6 ()
{
W t = { 1, 2 };
V s = __builtin_bit_cast (V, t);
- return s.b.a[1] == 1;
+ return s.b.a[1] == 1; // { dg-error "accessing uninitialized array element" }
}
constexpr bool a = f1 ();
constexpr bool b = f2 ();
-constexpr bool c = f3 (); // { dg-error "accessing uninitialized array element" }
-constexpr bool d = f4 ();
+constexpr bool c = f3 (); // { dg-message "in .constexpr. expansion" }
+constexpr bool d = f4 (); // { dg-message "in .constexpr. expansion" }
constexpr bool e = f5 ();
-constexpr bool f = f6 (); // { dg-error "accessing uninitialized array element" }
+constexpr bool f = f6 (); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
index 9c699dd55f0..e205bc6a8c1 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast12.C
@@ -33,7 +33,7 @@ f3 ()
{
T t = { 1, 2 };
S s = __builtin_bit_cast (S, t);
- return s.a[1] == 0;
+ return s.a[1] == 0; // { dg-error "accessing uninitialized array element" }
}
constexpr bool
@@ -57,12 +57,12 @@ f6 ()
{
W t = { 1, 2 };
V s = __builtin_bit_cast (V, t);
- return s.b.a[1] == 1;
+ return s.b.a[1] == 1; // { dg-error "accessing uninitialized array element" }
}
constexpr bool a = f1 ();
constexpr bool b = f2 ();
-constexpr bool c = f3 (); // { dg-error "accessing uninitialized array element" }
-constexpr bool d = f4 ();
+constexpr bool c = f3 (); // { dg-message "in .constexpr. expansion" }
+constexpr bool d = f4 (); // { dg-message "in .constexpr. expansion" }
constexpr bool e = f5 ();
-constexpr bool f = f6 (); // { dg-error "accessing uninitialized array element" }
+constexpr bool f = f6 (); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C b/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
index 5e185919be4..e0cc9a39702 100644
--- a/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
+++ b/gcc/testsuite/g++.dg/cpp2a/bit-cast14.C
@@ -44,7 +44,7 @@ f5 ()
{
T1 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
- unsigned char a = s.a;
+ unsigned char a = s.a; // { dg-error "accessing uninitialized member" }
return true;
}
@@ -53,7 +53,7 @@ f6 ()
{
T2 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
- unsigned char b = s.b;
+ unsigned char b = s.b; // { dg-error "accessing uninitialized member" }
return true;
}
@@ -62,14 +62,14 @@ f7 ()
{
T3 t = { 0, 0, 0, 0, 0, 0, 0 };
S s = __builtin_bit_cast (S, t);
- unsigned char c = s.c;
+ unsigned char c = s.c; // { dg-error "accessing uninitialized member" }
return true;
}
constexpr bool a = f1 ();
constexpr bool b = f2 ();
constexpr bool c = f3 ();
-constexpr bool d = f4 ();
-constexpr bool e = f5 (); // { dg-error "accessing uninitialized member" }
-constexpr bool f = f6 (); // { dg-error "accessing uninitialized member" }
-constexpr bool g = f7 (); // { dg-error "accessing uninitialized member" }
+constexpr bool d = f4 (); // { dg-message "in .constexpr. expansion" }
+constexpr bool e = f5 (); // { dg-message "in .constexpr. expansion" }
+constexpr bool f = f6 (); // { dg-message "in .constexpr. expansion" }
+constexpr bool g = f7 (); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
index 01bdfa5bd4d..b0c91d5ef97 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C
@@ -9,7 +9,7 @@ bar ()
{
V f { .b = 42 };
constexpr auto m = &V::a;
- return (f.*m) == 42;
+ return (f.*m) == 42; // { dg-error "accessing 'V::a' member instead of initialized 'V::b' member in constant expression" }
}
constexpr bool
@@ -21,5 +21,5 @@ baz ()
}
static_assert (bar (), ""); // { dg-error "non-constant condition for static assertion" }
- // { dg-error "accessing 'V::a' member instead of initialized 'V::b' member in constant expression" "" { target *-*-* } .-1 }
+ // { dg-message "in .constexpr. expansion" "" { target *-*-* } .-1 }
static_assert (baz (), "");
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
index a26678e6ed7..28facf192df 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-dynamic17.C
@@ -25,8 +25,7 @@ struct D : B, A {
constexpr B::B(V* v, A* a)
{
- dynamic_cast<B*>(a);
+ dynamic_cast<B*>(a); // { dg-error "accessing uninitialized member" }
}
-constexpr D d; // { dg-error "accessing uninitialized member" }
-// { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr D d; // { dg-message "in 'constexpr' expansion of" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
index e56ecfed48a..b4e39b6f928 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
@@ -52,11 +52,10 @@ constexpr int
fn5 ()
{
struct S { int a = 9; int b; } s;
- return s.b;
+ return s.b; // { dg-error "accessing uninitialized member" }
}
-constexpr int b = fn5 (); // { dg-error "accessing uninitialized member" }
-// { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
+constexpr int b = fn5 (); // { dg-message "in .constexpr. expansion of" }
constexpr int
fn6 ()
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
index 5a3d06a5fab..832782e1427 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C
@@ -17,11 +17,11 @@ struct B : A {
constexpr int
foo ()
{
- A *a = new B ();
+ A *a = new B (); // { dg-message "allocated here" }
a->a = 4;
delete a;
- int r = a->foo ();
+ int r = a->foo (); // { dg-error "constant expression" }
return r;
}
-constexpr auto a = foo (); // { dg-error "constant expression" }
+constexpr auto a = foo (); // { dg-message "in .constexpr. expansion" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
index 70b841208f8..3ba440fec53 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C
@@ -45,11 +45,10 @@ constexpr bool
f5 ()
{
int *p = new int; // { dg-message "allocated here" }
- return *p == 1;
+ return *p == 1; // { dg-error "the content of uninitialized storage is not usable in a constant expression" }
}
-constexpr auto v5 = f5 (); // { dg-error "the content of uninitialized storage is not usable in a constant expression" }
- // { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr auto v5 = f5 (); // { dg-message "in 'constexpr' expansion of" }
constexpr bool
f6 ()
@@ -57,11 +56,10 @@ f6 ()
int *p = new int (2); // { dg-message "allocated here" }
int *q = p;
delete p;
- return *q == 2;
+ return *q == 2; // { dg-error "use of allocated storage after deallocation in a constant expression" }
}
-constexpr auto v6 = f6 (); // { dg-error "use of allocated storage after deallocation in a constant expression" }
- // { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr auto v6 = f6 (); // { dg-message "in 'constexpr' expansion of" }
constexpr int *
f7 ()
diff --git a/gcc/testsuite/g++.dg/cpp2a/constinit10.C b/gcc/testsuite/g++.dg/cpp2a/constinit10.C
index b678788541e..d2c49c41f91 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constinit10.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constinit10.C
@@ -11,15 +11,14 @@ struct S1
struct alignas(64) S2
{
constexpr S2 ()
- : m_tabS1()
+ : m_tabS1() // { dg-error "used before its definition" }
{}
S1 m_tabS1[7];
};
constinit S2 objX; // { dg-error ".constinit. variable .objX. does not have a constant initializer" }
-// { dg-error "used before its definition" "" { target *-*-* } .-1 }
-// // { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-2 }
+// { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
constexpr S1::S1 ()
: m_i(14)
diff --git a/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C b/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
index 6b74090306b..241e9976e8c 100644
--- a/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
+++ b/gcc/testsuite/g++.dg/cpp2a/is-corresponding-member4.C
@@ -14,8 +14,8 @@ is_corresponding_member (M1 S1::*m1, M2 S2::*m2) noexcept
struct A { int a; };
struct B;
constexpr int B::*n = nullptr;
-constexpr auto a = std::is_corresponding_member (&A::a, n); // { dg-error "invalid use of incomplete type 'struct B'" }
-constexpr auto b = std::is_corresponding_member (n, &A::a); // { dg-error "invalid use of incomplete type 'struct B'" }
+constexpr auto a = std::is_corresponding_member (&A::a, n); // { dg-message "in .constexpr. expansion of" }
+constexpr auto b = std::is_corresponding_member (n, &A::a); // { dg-message "in .constexpr. expansion of" }
void
foo (int B::*m)
diff --git a/gcc/testsuite/g++.dg/ext/constexpr-vla2.C b/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
index d4ea7c58c0d..e09a27af3de 100644
--- a/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
+++ b/gcc/testsuite/g++.dg/ext/constexpr-vla2.C
@@ -4,7 +4,7 @@
constexpr int
fn_bad (int n)
{
- __extension__ int a [n] = { 0 };
+ __extension__ int a [n] = { 0 }; // { dg-error "array subscript" }
int z = a [0] + (n ? fn_bad (n - 1) : 0); // { dg-message "in .constexpr. expansion of " }
return z;
}
@@ -18,4 +18,4 @@ fn_ok (int n)
}
constexpr int i1 = fn_ok (3);
-constexpr int i2 = fn_bad (3); // { dg-error "array subscript|in .constexpr. expansion of " }
+constexpr int i2 = fn_bad (3); // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/ext/constexpr-vla3.C b/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
index 538b576a825..6f9daa1897f 100644
--- a/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
+++ b/gcc/testsuite/g++.dg/ext/constexpr-vla3.C
@@ -4,11 +4,11 @@
constexpr int
foo (int n)
{
- __extension__ int a[n] = { 1, 2, 3, 4, 5, 6 };
+ __extension__ int a[n] = { 1, 2, 3, 4, 5, 6 }; // { dg-error "array subscript" }
int z = 0;
for (int i = 0; i <= n; ++i)
z += a[i];
return z;
}
-constexpr int n = foo (3); // { dg-error "array subscript|in .constexpr. expansion of " }
+constexpr int n = foo (3); // { dg-message "in .constexpr. expansion of " }
diff --git a/gcc/testsuite/g++.dg/ubsan/pr63956.C b/gcc/testsuite/g++.dg/ubsan/pr63956.C
index 3a1596e6e2e..6fd0b4f893e 100644
--- a/gcc/testsuite/g++.dg/ubsan/pr63956.C
+++ b/gcc/testsuite/g++.dg/ubsan/pr63956.C
@@ -56,12 +56,13 @@ fn3 (int a, int b)
{
if (b != 2)
a = a / b; // { dg-error "..7 / 0.. is not a constant expression" }
+ // { dg-error "overflow in constant expression" "" { target *-*-* } .-1 }
return a;
}
constexpr int k1 = fn3 (8, 4);
constexpr int k2 = fn3 (7, 0); // { dg-message "in .constexpr. expansion" }
-constexpr int k3 = fn3 (INT_MIN, -1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int k3 = fn3 (INT_MIN, -1); // { dg-message "in .constexpr. expansion of " }
SA (k1 == 2);
@@ -100,13 +101,13 @@ constexpr int
fn7 (const int *a, int b)
{
if (b != 3)
- return fn6 (*a, b);
+ return fn6 (*a, b); // { dg-error "null pointer" }
return 7;
}
constexpr int n1 = 7;
constexpr int n2 = fn7 (&n1, 5);
-constexpr int n3 = fn7 ((const int *) 0, 8); // { dg-error "null pointer|in .constexpr. expansion of " }
+constexpr int n3 = fn7 ((const int *) 0, 8); // { dg-message "in .constexpr. expansion of " }
constexpr int
fn8 (int i)
@@ -122,15 +123,15 @@ constexpr int
fn9 (int a, int b)
{
if (b != 0)
- return a + b;
+ return a + b; // { dg-error "overflow in constant expression" }
return a;
}
constexpr int p1 = fn9 (42, 7);
-constexpr int p2 = fn9 (__INT_MAX__, 1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int p2 = fn9 (__INT_MAX__, 1); // { dg-message "in .constexpr. expansion of " }
constexpr int p3 = fn9 (__INT_MAX__, -1);
constexpr int p4 = fn9 (INT_MIN, 1);
-constexpr int p5 = fn9 (INT_MIN, -1); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int p5 = fn9 (INT_MIN, -1); // { dg-message "in .constexpr. expansion of " }
SA (p1 == 49);
SA (p3 == __INT_MAX__ - 1);
@@ -140,13 +141,13 @@ constexpr int
fn10 (int a, int b)
{
if (b != 0)
- return a * b;
+ return a * b; // { dg-error "overflow in constant expression" }
return a;
}
constexpr int q1 = fn10 (10, 10);
-constexpr int q2 = fn10 (__INT_MAX__, 2); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
-constexpr int q3 = fn10 (INT_MIN, 2); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int q2 = fn10 (__INT_MAX__, 2); // { dg-message "in .constexpr. expansion of " }
+constexpr int q3 = fn10 (INT_MIN, 2); // { dg-message "in .constexpr. expansion of " }
constexpr int q4 = fn10 (-1, -1);
SA (q1 == 100);
@@ -155,14 +156,14 @@ SA (q4 == 1);
constexpr int
fn11 (double d)
{
- int i = d;
+ int i = d; // { dg-error "overflow in constant expression" }
if (i != 0)
return i;
return i * 2;
}
constexpr int r1 = fn11 (3.4);
-constexpr int r2 = fn11 (__builtin_inf ()); // { dg-error "overflow in constant expression|in .constexpr. expansion of " }
+constexpr int r2 = fn11 (__builtin_inf ()); // { dg-message "in .constexpr. expansion of " }
constexpr int
fn12 (int i)
diff --git a/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc b/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
index 34ca5c4805c..fd89ac0e166 100644
--- a/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/equal/constexpr_neg.cc
@@ -32,7 +32,7 @@ test01()
return outa;
}
-static_assert(test01()); // { dg-error "outside the bounds" }
+static_assert(test01()); // { dg-error "non-constant condition" }
constexpr bool
test02()
@@ -44,7 +44,8 @@ test02()
return outa;
}
-static_assert(test02()); // { dg-error "outside the bounds" }
+static_assert(test02()); // { dg-error "non-constant condition" }
-// { dg-prune-output "non-constant condition" }
+// Errors occuring within <algorithm> internals:
+// { dg-error "outside the bounds of array" "" { target *-*-* } 0 }
// { dg-prune-output "in 'constexpr'" }
diff --git a/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc b/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
index 5b6fea7b560..bc9b29bc39d 100644
--- a/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
+++ b/libstdc++-v3/testsuite/26_numerics/gcd/105844.cc
@@ -13,9 +13,11 @@ static_assert( std::gcd(LLONG_MIN, 2ull) == 2 );
static_assert( std::gcd(2ull, LLONG_MIN) == 2 );
// But |INT_MIN| cannot be represented in common_type<int, int> i.e. int.
-constexpr int a = std::gcd(INT_MIN, 1); // { dg-error "overflow" }
-constexpr int b = std::gcd(1, INT_MIN); // { dg-error "overflow" }
+constexpr int a = std::gcd(INT_MIN, 1); // { dg-error "in .constexpr." }
+constexpr int b = std::gcd(1, INT_MIN); // { dg-error "in .constexpr." }
// And |LLONG_MIN| cannot be represented in long.
-constexpr long long c = std::gcd(LLONG_MIN, 1); // { dg-error "overflow" }
-constexpr long long d = std::gcd(1, LLONG_MIN); // { dg-error "overflow" }
+constexpr long long c = std::gcd(LLONG_MIN, 1); // { dg-error "in .constexpr." }
+constexpr long long d = std::gcd(1, LLONG_MIN); // { dg-error "in .constexpr." }
+
+// { dg-error "overflow" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc b/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
index d0e032e03e0..d853974f77e 100644
--- a/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
+++ b/libstdc++-v3/testsuite/26_numerics/lcm/105844.cc
@@ -9,14 +9,16 @@ static_assert( std::lcm(INT_MIN, 1u) == INT_MAX+1u );
static_assert( std::lcm(1u, INT_MIN) == INT_MAX+1u );
// But |INT_MIN| cannot be represented in common_type<int, int> i.e. int.
-constexpr int a = std::lcm(INT_MIN, 1); // { dg-error "overflow" }
-constexpr int b = std::lcm(1, INT_MIN); // { dg-error "overflow" }
+constexpr int a = std::lcm(INT_MIN, 1); // { dg-error "in .constexpr." }
+constexpr int b = std::lcm(1, INT_MIN); // { dg-error "in .constexpr." }
// And the LCM of 50000 and 49999 cannot be represented in int.
-constexpr int c = std::lcm(50000, 49999); // { dg-error "overflow" }
-constexpr int d = std::lcm(49999, 50000); // { dg-error "overflow" }
+constexpr int c = std::lcm(50000, 49999); // { dg-error "in .constexpr." }
+constexpr int d = std::lcm(49999, 50000); // { dg-error "in .constexpr." }
// Similarly for unsigned, but the diagnostic is a failed assertion instead.
-constexpr int e = std::lcm(500000u, 499999); // { dg-error "in 'constexpr'" }
-constexpr int f = std::lcm(499999u, 500000); // { dg-error "in 'constexpr'" }
+constexpr int e = std::lcm(500000u, 499999); // { dg-error "in .constexpr." }
+constexpr int f = std::lcm(499999u, 500000); // { dg-error "in .constexpr." }
+
+// { dg-error "overflow" "" { target *-*-* } 0 }
// { dg-error "unreachable" "" { target *-*-* } 0 }
--
2.41.0
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...]
2023-07-01 3:24 [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Nathaniel Shead
` (2 preceding siblings ...)
2023-07-01 3:30 ` [PATCH v3 3/3] c++: Improve location information in constant evaluation Nathaniel Shead
@ 2023-07-10 19:23 ` Patrick Palka
3 siblings, 0 replies; 9+ messages in thread
From: Patrick Palka @ 2023-07-10 19:23 UTC (permalink / raw)
To: Nathaniel Shead; +Cc: gcc-patches, Patrick Palka, jason
On Sat, 1 Jul 2023, Nathaniel Shead wrote:
> This is an update of the patch series at
> https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614811.html
>
> Changes since v2:
>
> - Use a separate 'hash_set' to track expired variables instead of
> adding a flag to 'lang_decl_base'.
> - Use 'iloc_sentinel' to propagate location information down to
> subexpressions instead of manually saving and falling back to a
> parent expression's location.
> - Update more tests with improved error location information.
Thanks very much! This patch series looks good to me.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu.
>
> ---
>
> Nathaniel Shead (3):
> c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
> c++: Improve constexpr error for dangling local variables
> c++: Improve location information in constant evaluation
>
> gcc/cp/constexpr.cc | 158 +++++++++++++++---
> gcc/cp/semantics.cc | 5 +-
> gcc/cp/typeck.cc | 5 +-
> gcc/testsuite/g++.dg/cpp0x/constexpr-48089.C | 10 +-
> gcc/testsuite/g++.dg/cpp0x/constexpr-70323.C | 8 +-
> gcc/testsuite/g++.dg/cpp0x/constexpr-70323a.C | 8 +-
> .../g++.dg/cpp0x/constexpr-delete2.C | 5 +-
> gcc/testsuite/g++.dg/cpp0x/constexpr-diag3.C | 2 +-
> gcc/testsuite/g++.dg/cpp0x/constexpr-ice20.C | 1 +
> .../g++.dg/cpp0x/constexpr-recursion.C | 6 +-
> gcc/testsuite/g++.dg/cpp0x/overflow1.C | 2 +-
> gcc/testsuite/g++.dg/cpp1y/constexpr-89285.C | 5 +-
> gcc/testsuite/g++.dg/cpp1y/constexpr-89481.C | 3 +-
> .../g++.dg/cpp1y/constexpr-lifetime1.C | 14 ++
> .../g++.dg/cpp1y/constexpr-lifetime2.C | 20 +++
> .../g++.dg/cpp1y/constexpr-lifetime3.C | 13 ++
> .../g++.dg/cpp1y/constexpr-lifetime4.C | 11 ++
> .../g++.dg/cpp1y/constexpr-lifetime5.C | 11 ++
> .../g++.dg/cpp1y/constexpr-tracking-const14.C | 3 +-
> .../g++.dg/cpp1y/constexpr-tracking-const16.C | 3 +-
> .../g++.dg/cpp1y/constexpr-tracking-const18.C | 4 +-
> .../g++.dg/cpp1y/constexpr-tracking-const19.C | 4 +-
> .../g++.dg/cpp1y/constexpr-tracking-const21.C | 4 +-
> .../g++.dg/cpp1y/constexpr-tracking-const22.C | 4 +-
> .../g++.dg/cpp1y/constexpr-tracking-const3.C | 3 +-
> .../g++.dg/cpp1y/constexpr-tracking-const4.C | 3 +-
> .../g++.dg/cpp1y/constexpr-tracking-const7.C | 3 +-
> gcc/testsuite/g++.dg/cpp1y/constexpr-union5.C | 4 +-
> gcc/testsuite/g++.dg/cpp1y/pr68180.C | 4 +-
> .../g++.dg/cpp1z/constexpr-lambda6.C | 4 +-
> .../g++.dg/cpp1z/constexpr-lambda8.C | 5 +-
> gcc/testsuite/g++.dg/cpp2a/bit-cast11.C | 10 +-
> gcc/testsuite/g++.dg/cpp2a/bit-cast12.C | 10 +-
> gcc/testsuite/g++.dg/cpp2a/bit-cast14.C | 14 +-
> gcc/testsuite/g++.dg/cpp2a/constexpr-98122.C | 4 +-
> .../g++.dg/cpp2a/constexpr-dynamic17.C | 5 +-
> gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C | 5 +-
> gcc/testsuite/g++.dg/cpp2a/constexpr-new12.C | 6 +-
> gcc/testsuite/g++.dg/cpp2a/constexpr-new3.C | 10 +-
> gcc/testsuite/g++.dg/cpp2a/constinit10.C | 5 +-
> .../g++.dg/cpp2a/is-corresponding-member4.C | 4 +-
> gcc/testsuite/g++.dg/ext/constexpr-vla2.C | 4 +-
> gcc/testsuite/g++.dg/ext/constexpr-vla3.C | 4 +-
> gcc/testsuite/g++.dg/ubsan/pr63956.C | 23 +--
> .../g++.dg/warn/Wreturn-local-addr-6.C | 3 -
> .../25_algorithms/equal/constexpr_neg.cc | 7 +-
> .../testsuite/26_numerics/gcd/105844.cc | 10 +-
> .../testsuite/26_numerics/lcm/105844.cc | 14 +-
> 48 files changed, 330 insertions(+), 143 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime1.C
> create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime2.C
> create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime3.C
> create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime4.C
> create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lifetime5.C
>
> --
> 2.41.0
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
2023-07-01 3:28 ` [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675] Nathaniel Shead
@ 2023-07-14 15:16 ` Jason Merrill
2023-07-14 22:40 ` Jason Merrill
2023-07-16 13:47 ` Nathaniel Shead
0 siblings, 2 replies; 9+ messages in thread
From: Jason Merrill @ 2023-07-14 15:16 UTC (permalink / raw)
To: Nathaniel Shead, gcc-patches; +Cc: Patrick Palka
On 6/30/23 23:28, Nathaniel Shead via Gcc-patches wrote:
> This adds rudimentary lifetime tracking in C++ constexpr contexts,
Thanks!
I'm not seeing either a copyright assignment or DCO certification for
you; please see https://gcc.gnu.org/contribute.html#legal for more
information.
> diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> index cca0435bafc..bc59b4aab67 100644
> --- a/gcc/cp/constexpr.cc
> +++ b/gcc/cp/constexpr.cc
> @@ -1188,7 +1190,12 @@ public:
> if (!already_in_map && modifiable)
> modifiable->add (t);
> }
> - void remove_value (tree t) { values.remove (t); }
> + void remove_value (tree t)
> + {
> + if (DECL_P (t))
> + outside_lifetime.add (t);
> + values.remove (t);
What if, instead of removing the variable from one hash table and adding
it to another, we change the value to, say, void_node?
> + /* Also don't cache a call if we return a pointer to an expired
> + value. */
> + if (cacheable && (cp_walk_tree_without_duplicates
> + (&result, find_expired_values,
> + &ctx->global->outside_lifetime)))
> + cacheable = false;
I think we need to reconsider cacheability in general; I think we only
want to cache calls that are themselves valid constant expressions, in
that the return value is a "permitted result of a constant expression"
(https://eel.is/c++draft/expr.const#13). A pointer to an automatic
variable is not, whether or not it is currently within its lifetime.
That is, only cacheable if reduced_constant_expression_p (result).
I'm experimenting with this now, you don't need to mess with it.
> @@ -7085,7 +7138,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
> case PARM_DECL:
> if (lval && !TYPE_REF_P (TREE_TYPE (t)))
> /* glvalue use. */;
> - else if (tree v = ctx->global->get_value (r))
> + else if (tree v = ctx->global->get_value (t))
I agree with this change, but it doesn't have any actual effect, right?
I'll go ahead and apply it separately.
> @@ -7328,17 +7386,28 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
> auto_vec<tree, 2> cleanups;
> vec<tree> *prev_cleanups = ctx->global->cleanups;
> ctx->global->cleanups = &cleanups;
> - r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
> +
> + auto_vec<tree, 10> save_exprs;
Now that we're going to track temporaries for each full-expression, I
think we shouldn't also need to track them for loops and calls.
Jason
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
2023-07-14 15:16 ` Jason Merrill
@ 2023-07-14 22:40 ` Jason Merrill
2023-07-16 13:47 ` Nathaniel Shead
1 sibling, 0 replies; 9+ messages in thread
From: Jason Merrill @ 2023-07-14 22:40 UTC (permalink / raw)
To: Nathaniel Shead, gcc-patches; +Cc: Patrick Palka
On 7/14/23 11:16, Jason Merrill wrote:
> I'm not seeing either a copyright assignment or DCO certification for
> you; please see https://gcc.gnu.org/contribute.html#legal for more
> information.
Oops, now I see the DCO sign-off, not sure how I was missing it.
Jason
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
2023-07-14 15:16 ` Jason Merrill
2023-07-14 22:40 ` Jason Merrill
@ 2023-07-16 13:47 ` Nathaniel Shead
2023-07-17 16:04 ` Jason Merrill
1 sibling, 1 reply; 9+ messages in thread
From: Nathaniel Shead @ 2023-07-16 13:47 UTC (permalink / raw)
To: Jason Merrill; +Cc: gcc-patches, Patrick Palka
On Fri, Jul 14, 2023 at 11:16:58AM -0400, Jason Merrill wrote:
> On 6/30/23 23:28, Nathaniel Shead via Gcc-patches wrote:
> > This adds rudimentary lifetime tracking in C++ constexpr contexts,
>
> Thanks!
>
> I'm not seeing either a copyright assignment or DCO certification for you;
> please see https://gcc.gnu.org/contribute.html#legal for more information.
>
> > diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> > index cca0435bafc..bc59b4aab67 100644
> > --- a/gcc/cp/constexpr.cc
> > +++ b/gcc/cp/constexpr.cc
> > @@ -1188,7 +1190,12 @@ public:
> > if (!already_in_map && modifiable)
> > modifiable->add (t);
> > }
> > - void remove_value (tree t) { values.remove (t); }
> > + void remove_value (tree t)
> > + {
> > + if (DECL_P (t))
> > + outside_lifetime.add (t);
> > + values.remove (t);
>
> What if, instead of removing the variable from one hash table and adding it
> to another, we change the value to, say, void_node?
I have another patch I'm working on after this which does seem to
require the overlapping tables to properly catch uses of aggregates
while they are still being constructed (i.e. before their lifetime has
begun), as part of PR c++/109518. In that case the 'values' map contains
the CONSTRUCTOR node for the aggregate, but it also needs to be in
'outside_lifetime'. I could also explore solving this another way
however if you prefer.
(I also have vague dreams of at some point making this a map to the
location that the object was destroyed for more context in the error
messages, but I'm not yet sure if that's feasible or will actually be
all that helpful so I'm happy to forgo that.)
> > + /* Also don't cache a call if we return a pointer to an expired
> > + value. */
> > + if (cacheable && (cp_walk_tree_without_duplicates
> > + (&result, find_expired_values,
> > + &ctx->global->outside_lifetime)))
> > + cacheable = false;
>
> I think we need to reconsider cacheability in general; I think we only want
> to cache calls that are themselves valid constant expressions, in that the
> return value is a "permitted result of a constant expression"
> (https://eel.is/c++draft/expr.const#13). A pointer to an automatic variable
> is not, whether or not it is currently within its lifetime.
>
> That is, only cacheable if reduced_constant_expression_p (result).
>
> I'm experimenting with this now, you don't need to mess with it.
Thanks! I agree, that sounds a lot nicer; I definitely ran into caching
problems in a few different ways when I was developing this patch, and
this approach sounds like it would have avoided that.
> > @@ -7085,7 +7138,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
> > case PARM_DECL:
> > if (lval && !TYPE_REF_P (TREE_TYPE (t)))
> > /* glvalue use. */;
> > - else if (tree v = ctx->global->get_value (r))
> > + else if (tree v = ctx->global->get_value (t))
>
> I agree with this change, but it doesn't have any actual effect, right? I'll
> go ahead and apply it separately.
Yup, it was just a drive-by cleanup I made while trying to understand
this part of the code. Thanks.
> > @@ -7328,17 +7386,28 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
> > auto_vec<tree, 2> cleanups;
> > vec<tree> *prev_cleanups = ctx->global->cleanups;
> > ctx->global->cleanups = &cleanups;
> > - r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
> > +
> > + auto_vec<tree, 10> save_exprs;
>
> Now that we're going to track temporaries for each full-expression, I think
> we shouldn't also need to track them for loops and calls.
Good point, I didn't think about that. I'm now bootstrapping/regtesting
a modification of this patch that removes the tracking in loops and
calls, but an initial run of the dg.exp testsuite is promising. It also
fixes an issue I just noticed where I don't actually check lifetimes of
empty types.
I'll send out a new version when that finishes.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675]
2023-07-16 13:47 ` Nathaniel Shead
@ 2023-07-17 16:04 ` Jason Merrill
0 siblings, 0 replies; 9+ messages in thread
From: Jason Merrill @ 2023-07-17 16:04 UTC (permalink / raw)
To: Nathaniel Shead; +Cc: gcc-patches, Patrick Palka
On 7/16/23 09:47, Nathaniel Shead wrote:
> On Fri, Jul 14, 2023 at 11:16:58AM -0400, Jason Merrill wrote:
>>
>> What if, instead of removing the variable from one hash table and adding it
>> to another, we change the value to, say, void_node?
>
> I have another patch I'm working on after this which does seem to
> require the overlapping tables to properly catch uses of aggregates
> while they are still being constructed (i.e. before their lifetime has
> begun), as part of PR c++/109518. In that case the 'values' map contains
> the CONSTRUCTOR node for the aggregate, but it also needs to be in
> 'outside_lifetime'. I could also explore solving this another way
> however if you prefer.
I'd think to handle this with a flag on the CONSTRUCTOR to indicate that
members with no value are out of lifetime (so, a stronger version of
CONSTRUCTOR_NO_CLEARING that just indicates uninitialized). Currently
all the TREE_LANG_FLAG_* are occupied on CONSTRUCTOR, but there seem to
be plenty of spare bits to add a TREE_LANG_FLAG_7.
It might make sense to access those two flags with accessor functions so
they stay aligned.
> (I also have vague dreams of at some point making this a map to the
> location that the object was destroyed for more context in the error
> messages, but I'm not yet sure if that's feasible or will actually be
> all that helpful so I'm happy to forgo that.)
Hmm, that sounds convenient for debugging, but affected cases would also
be straightforward to debug by adding a run-time call, so I'm skeptical
it would be worth the overhead for successful compiles.
Jason
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-07-17 16:04 UTC | newest]
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2023-07-01 3:24 [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Nathaniel Shead
2023-07-01 3:28 ` [PATCH v3 1/3] c++: Track lifetimes in constant evaluation [PR70331,PR96630,PR98675] Nathaniel Shead
2023-07-14 15:16 ` Jason Merrill
2023-07-14 22:40 ` Jason Merrill
2023-07-16 13:47 ` Nathaniel Shead
2023-07-17 16:04 ` Jason Merrill
2023-07-01 3:30 ` [PATCH v3 2/3] c++: Improve constexpr error for dangling local variables Nathaniel Shead
2023-07-01 3:30 ` [PATCH v3 3/3] c++: Improve location information in constant evaluation Nathaniel Shead
2023-07-10 19:23 ` [PATCH v3 0/3] c++: Track lifetimes in constant evaluation [PR70331,...] Patrick Palka
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