From: Marek Polacek <polacek@redhat.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>, Jason Merrill <jason@redhat.com>
Subject: [PATCH] c++: -Wuninitialized when binding a ref to uninit DM [PR113987]
Date: Tue, 20 Feb 2024 19:15:17 -0500 [thread overview]
Message-ID: <20240221001517.478667-1-polacek@redhat.com> (raw)
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This PR asks that our -Wuninitialized for mem-initializers does
not warn when binding a reference to an uninitialized data member.
We already check !INDIRECT_TYPE_P in find_uninit_fields_r, but
that won't catch binding a parameter of a reference type to an
uninitialized field, as in:
struct S { S (int&); };
struct T {
T() : s(i) {}
S s;
int i;
};
This patch adds a new function to handle this case.
PR c++/113987
gcc/cp/ChangeLog:
* call.cc (conv_binds_to_reference_parm_p): New.
* cp-tree.h (conv_binds_to_reference_parm_p): Declare.
* init.cc (find_uninit_fields_r): Call it.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wuninitialized-15.C: Turn dg-warning into dg-bogus.
* g++.dg/warn/Wuninitialized-34.C: New test.
---
gcc/cp/call.cc | 24 ++++++++++++++
gcc/cp/cp-tree.h | 1 +
gcc/cp/init.cc | 3 +-
gcc/testsuite/g++.dg/warn/Wuninitialized-15.C | 3 +-
gcc/testsuite/g++.dg/warn/Wuninitialized-34.C | 32 +++++++++++++++++++
5 files changed, 60 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 1dac1470d3b..c40ef2e3028 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -14551,4 +14551,28 @@ maybe_show_nonconverting_candidate (tree to, tree from, tree arg, int flags)
"function was not considered");
}
+/* We're converting EXPR to TYPE. If that conversion involves a conversion
+ function and we're binding EXPR to a reference parameter of that function,
+ return true. */
+
+bool
+conv_binds_to_reference_parm_p (tree type, tree expr)
+{
+ conversion_obstack_sentinel cos;
+ conversion *c = implicit_conversion (type, TREE_TYPE (expr), expr,
+ /*c_cast_p=*/false, LOOKUP_NORMAL,
+ tf_none);
+ if (c && !c->bad_p && c->user_conv_p)
+ for (; c; c = next_conversion (c))
+ if (c->kind == ck_user)
+ for (z_candidate *cand = c->cand; cand; cand = cand->next)
+ if (cand->viable == 1)
+ for (size_t i = 0; i < cand->num_convs; ++i)
+ if (cand->convs[i]->kind == ck_ref_bind
+ && conv_get_original_expr (cand->convs[i]) == expr)
+ return true;
+
+ return false;
+}
+
#include "gt-cp-call.h"
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 334c11396c2..ce2d85f1f86 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6845,6 +6845,7 @@ extern void cp_warn_deprecated_use_scopes (tree);
extern tree get_function_version_dispatcher (tree);
extern bool any_template_arguments_need_structural_equality_p (tree);
extern void maybe_show_nonconverting_candidate (tree, tree, tree, int);
+extern bool conv_binds_to_reference_parm_p (tree, tree);
/* in class.cc */
extern tree build_vfield_ref (tree, tree);
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index ac37330527e..1a341f7e606 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -906,7 +906,8 @@ find_uninit_fields_r (tree *tp, int *walk_subtrees, void *data)
warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
"reference %qD is not yet bound to a value when used "
"here", field);
- else if (!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
+ else if ((!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
+ && !conv_binds_to_reference_parm_p (type, init))
warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
"member %qD is used uninitialized", field);
*walk_subtrees = false;
diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
index 89e90668c41..2fd33037bfd 100644
--- a/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
+++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
@@ -65,8 +65,7 @@ struct H {
G g;
A a2;
H() : g(a1) { }
- // ??? clang++ doesn't warn here
- H(int) : g(a2) { } // { dg-warning "member .H::a2. is used uninitialized" }
+ H(int) : g(a2) { } // { dg-bogus "member .H::a2. is used uninitialized" }
};
struct I {
diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
new file mode 100644
index 00000000000..28226d8032e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
@@ -0,0 +1,32 @@
+// PR c++/113987
+// { dg-do compile }
+// { dg-options "-Wuninitialized" }
+
+struct t1 {
+ t1(int);
+};
+struct t2 {
+ t2(int&, int = 0);
+ t2(double&, int = 0);
+};
+struct t3 {
+ t3(int&);
+};
+struct t4 {};
+void f1(int&);
+struct t {
+ t() :
+ v1(i), // { dg-warning "is used uninitialized" }
+ v2(i),
+ v3(i),
+ v4((f1(i), t4())),
+ v5(i) {}
+ t1 v1;
+ t2 v2;
+ t3 v3;
+ t4 v4;
+ t1 v5;
+ int i;
+ int j;
+};
+int main() { t v1; }
base-commit: ca5f509903315a56b2f306f8644544861a6525cb
--
2.43.2
next reply other threads:[~2024-02-21 0:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-21 0:15 Marek Polacek [this message]
2024-02-22 8:34 ` Jason Merrill
2024-02-22 19:28 ` Marek Polacek
2024-02-28 23:21 ` Jason Merrill
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