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From: Patrick Palka <ppalka@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: Patrick Palka <ppalka@redhat.com>,
	gcc-patches@gcc.gnu.org,  libstdc++@gcc.gnu.org
Subject: Re: [PATCH] c++: non-dependent assignment checking [PR63198, PR18474]
Date: Mon, 18 Sep 2023 09:12:33 -0400 (EDT)	[thread overview]
Message-ID: <cb4c996e-7d84-58f0-51dd-d2e8830839fc@idea> (raw)
In-Reply-To: <13272bff-9f95-4dfd-d724-ff67cc568532@redhat.com>

On Sun, 17 Sep 2023, Jason Merrill wrote:

> On 9/17/23 14:51, Patrick Palka wrote:
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> > trunk?  Patch generatde with -w to avoid noisy whitespace changes.
> > 
> > -- >8 --
> > 
> > This patch makes us recognize and check non-dependent simple assigments
> > ahead of time, like we already do for compound assignments.  This means
> > the templated representation of such assignments will now usually have
> > an implicit INDIRECT_REF (due to the reference return type), which the
> > -Wparentheses code needs to handle.  As a drive-by improvement, this
> > patch also makes maybe_convert_cond issue -Wparentheses warnings ahead
> > of time.
> > 
> > This revealed some libstdc++ tests were attempting to modify a data
> > member from a uninstantiated const member function; naively fixed by
> > making the data member mutable.
> > 
> > 	PR c++/63198
> > 	PR c++/18474
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* semantics.cc (maybe_convert_cond): Look through implicit
> > 	INDIRECT_REF when deciding whether to issue a -Wparentheses
> > 	warning, and consider templated assignment expressions as well.
> > 	(finish_parenthesized_expr): Look through implicit INDIRECT_REF
> > 	when suppressing -Wparentheses warning.
> > 	* typeck.cc (build_x_modify_expr): Check simple assignments
> > 	ahead time too, not just compound assignments.  Give the second
> > 	operand of MODOP_EXPR a non-null type so that it's not considered
> > 	always instantiation-dependent.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	* g++.dg/cpp0x/static_assert15.C: Expect diagnostic for
> > 	non-constant static_assert condition.
> > 	* g++.dg/expr/unary2.C: Remove xfails.
> > 	* g++.dg/template/init7.C: Make initializer type-dependent to
> > 	preserve intent of test.
> > 	* g++.dg/template/recurse3.C: Likewise for the erroneous
> > 	statement.
> > 	* g++.dg/template/non-dependent26.C: New test.
> > 	* g++.dg/warn/Wparentheses-32.C: New test.
> > 
> > libstdc++/ChangeLog:
> > 
> > 	* testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc:
> > 	Make seed_seq::called member mutable.
> > 	*
> > testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc:
> > 	Likewise.
> > 	*
> > testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc
> > 	Likewise.
> > 	*
> > testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc:
> > 	Likewise.
> > 	* testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc:
> > 	Likewise.
> > 	*
> > testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc:
> > 	Likewise.
> > 	*
> > testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc
> > 	Likewise.
> > ---
> >   gcc/cp/semantics.cc                           | 17 +++++++----
> >   gcc/cp/typeck.cc                              | 23 +++++++--------
> >   gcc/testsuite/g++.dg/cpp0x/static_assert15.C  |  2 +-
> >   gcc/testsuite/g++.dg/expr/unary2.C            |  8 ++----
> >   gcc/testsuite/g++.dg/template/init7.C         |  2 +-
> >   .../g++.dg/template/non-dependent26.C         | 25 +++++++++++++++++
> >   gcc/testsuite/g++.dg/template/recurse3.C      |  8 +++---
> >   gcc/testsuite/g++.dg/warn/Wparentheses-32.C   | 28 +++++++++++++++++++
> >   .../discard_block_engine/cons/seed_seq2.cc    |  2 +-
> >   .../independent_bits_engine/cons/seed_seq2.cc |  2 +-
> >   .../cons/seed_seq2.cc                         |  2 +-
> >   .../mersenne_twister_engine/cons/seed_seq2.cc |  2 +-
> >   .../shuffle_order_engine/cons/seed_seq2.cc    |  2 +-
> >   .../cons/seed_seq2.cc                         |  2 +-
> >   .../cons/seed_seq2.cc                         |  2 +-
> >   15 files changed, 91 insertions(+), 36 deletions(-)
> >   create mode 100644 gcc/testsuite/g++.dg/template/non-dependent26.C
> >   create mode 100644 gcc/testsuite/g++.dg/warn/Wparentheses-32.C
> > 
> > diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> > index 0f7f4e87ae4..b57c1ac868b 100644
> > --- a/gcc/cp/semantics.cc
> > +++ b/gcc/cp/semantics.cc
> > diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
> > index 459739d5866..74f5fced060 100644
> > --- a/gcc/cp/typeck.cc
> > +++ b/gcc/cp/typeck.cc
> > @@ -9739,15 +9739,15 @@ build_x_modify_expr (location_t loc, tree lhs, enum
> > tree_code modifycode,
> >         rhs = build_non_dependent_expr (rhs);
> >       }
> >   -  if (modifycode != NOP_EXPR)
> > -    {
> > -      tree op = build_nt (modifycode, NULL_TREE, NULL_TREE);
> > -      tree rval = build_new_op (loc, MODIFY_EXPR, LOOKUP_NORMAL,
> > +  tree rval;
> > +  if (modifycode == NOP_EXPR)
> > +    rval = cp_build_modify_expr (loc, lhs, modifycode, rhs, complain);
> > +  else
> > +    rval = build_new_op (loc, MODIFY_EXPR, LOOKUP_NORMAL,
> >   			 lhs, rhs, op, lookups, &overload, complain);
> > -      if (rval)
> > -	{
> >     if (rval == error_mark_node)
> > -	    return rval;
> > +    return error_mark_node;
> > +  if (modifycode != NOP_EXPR)
> >       suppress_warning (rval /* What warning? */);
> 
> Did you try disabling this to see if it's still needed?

Looks like it's not needed as far as bootstrap + regtest is concerned.
FWIW this line originally was added in
https://gcc.gnu.org/pipermail/gcc-patches/2004-July/144621.html
to suppress -Wparentheses warnings for non-templated compound assignment
operator expressions.

Here's a patch that also gets rid of that suppress_warning call:

-- >8 --

Subject: [PATCH] c++: non-dependent assignment checking [PR63198, PR18474]

	PR c++/63198
	PR c++/18474

gcc/cp/ChangeLog:

	* semantics.cc (maybe_convert_cond): Look through implicit
	INDIRECT_REF when deciding whether to issue a -Wparentheses
	warning, and consider templated assignment expressions as well.
	(finish_parenthesized_expr): Look through implicit INDIRECT_REF
	when suppressing -Wparentheses warning.
	* typeck.cc (build_x_modify_expr): Check simple assignments
	ahead time too, not just compound assignments.  Give the second
	operand of MODOP_EXPR a non-null type so that it's not considered
	always instantiation-dependent.  Don't call suppress_warning.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/static_assert15.C: Expect diagnostic for
	non-constant static_assert condition.
	* g++.dg/expr/unary2.C: Remove xfails.
	* g++.dg/template/init7.C: Make initializer type-dependent to
	preserve intent of test.
	* g++.dg/template/recurse3.C: Likewise for the erroneous
	statement.
	* g++.dg/template/non-dependent26.C: New test.
	* g++.dg/warn/Wparentheses-32.C: New test.

libstdc++/ChangeLog:

	* testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc:
	Make data member seed_seq::called mutable.
	* testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc:
	Likewise.
	* testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc
	Likewise.
	* testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc:
	Likewise.
	* testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc:
	Likewise.
	* testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc:
	Likewise.
	* testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc
	Likewise.
---
 gcc/cp/semantics.cc                           | 19 ++++++---
 gcc/cp/typeck.cc                              | 41 ++++++++-----------
 gcc/testsuite/g++.dg/cpp0x/static_assert15.C  |  2 +-
 gcc/testsuite/g++.dg/expr/unary2.C            |  8 ++--
 gcc/testsuite/g++.dg/template/init7.C         |  2 +-
 .../g++.dg/template/non-dependent26.C         | 25 +++++++++++
 gcc/testsuite/g++.dg/template/recurse3.C      |  8 ++--
 gcc/testsuite/g++.dg/warn/Wparentheses-32.C   | 28 +++++++++++++
 .../discard_block_engine/cons/seed_seq2.cc    |  2 +-
 .../independent_bits_engine/cons/seed_seq2.cc |  2 +-
 .../cons/seed_seq2.cc                         |  2 +-
 .../mersenne_twister_engine/cons/seed_seq2.cc |  2 +-
 .../shuffle_order_engine/cons/seed_seq2.cc    |  2 +-
 .../cons/seed_seq2.cc                         |  2 +-
 .../cons/seed_seq2.cc                         |  2 +-
 15 files changed, 100 insertions(+), 47 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/template/non-dependent26.C
 create mode 100644 gcc/testsuite/g++.dg/warn/Wparentheses-32.C

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 0f7f4e87ae4..4109ac33654 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -881,13 +881,17 @@ maybe_convert_cond (tree cond)
   /* Do the conversion.  */
   cond = convert_from_reference (cond);
 
-  if ((TREE_CODE (cond) == MODIFY_EXPR || is_assignment_op_expr_p (cond))
+  tree inner = REFERENCE_REF_P (cond) ? TREE_OPERAND (cond, 0) : cond;
+  if ((TREE_CODE (inner) == MODIFY_EXPR
+       || (TREE_CODE (inner) == MODOP_EXPR
+	   && TREE_CODE (TREE_OPERAND (inner, 1)) == NOP_EXPR)
+       || is_assignment_op_expr_p (inner))
       && warn_parentheses
-      && !warning_suppressed_p (cond, OPT_Wparentheses)
-      && warning_at (cp_expr_loc_or_input_loc (cond),
+      && !warning_suppressed_p (inner, OPT_Wparentheses)
+      && warning_at (cp_expr_loc_or_input_loc (inner),
 		     OPT_Wparentheses, "suggest parentheses around "
 				       "assignment used as truth value"))
-    suppress_warning (cond, OPT_Wparentheses);
+    suppress_warning (inner, OPT_Wparentheses);
 
   return condition_conversion (cond);
 }
@@ -2155,8 +2159,11 @@ cp_expr
 finish_parenthesized_expr (cp_expr expr)
 {
   if (EXPR_P (expr))
-    /* This inhibits warnings in c_common_truthvalue_conversion.  */
-    suppress_warning (expr, OPT_Wparentheses);
+    {
+      /* This inhibits warnings in c_common_truthvalue_conversion.  */
+      tree inner = REFERENCE_REF_P (expr) ? TREE_OPERAND (expr, 0) : *expr;
+      suppress_warning (inner, OPT_Wparentheses);
+    }
 
   if (TREE_CODE (expr) == OFFSET_REF
       || TREE_CODE (expr) == SCOPE_REF)
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 459739d5866..8132bd7fccc 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -9721,13 +9721,13 @@ build_x_modify_expr (location_t loc, tree lhs, enum tree_code modifycode,
   if (lhs == error_mark_node || rhs == error_mark_node)
     return cp_expr (error_mark_node, loc);
 
+  tree op = build_min (modifycode, void_type_node, NULL_TREE, NULL_TREE);
+
   if (processing_template_decl)
     {
-      if (modifycode == NOP_EXPR
-	  || type_dependent_expression_p (lhs)
+      if (type_dependent_expression_p (lhs)
 	  || type_dependent_expression_p (rhs))
 	{
-	  tree op = build_min_nt_loc (loc, modifycode, NULL_TREE, NULL_TREE);
 	  tree rval = build_min_nt_loc (loc, MODOP_EXPR, lhs, op, rhs);
 	  if (modifycode != NOP_EXPR)
 	    TREE_TYPE (rval)
@@ -9739,29 +9739,24 @@ build_x_modify_expr (location_t loc, tree lhs, enum tree_code modifycode,
       rhs = build_non_dependent_expr (rhs);
     }
 
-  if (modifycode != NOP_EXPR)
+  tree rval;
+  if (modifycode == NOP_EXPR)
+    rval = cp_build_modify_expr (loc, lhs, modifycode, rhs, complain);
+  else
+    rval = build_new_op (loc, MODIFY_EXPR, LOOKUP_NORMAL,
+			 lhs, rhs, op, lookups, &overload, complain);
+  if (rval == error_mark_node)
+    return error_mark_node;
+  if (processing_template_decl)
     {
-      tree op = build_nt (modifycode, NULL_TREE, NULL_TREE);
-      tree rval = build_new_op (loc, MODIFY_EXPR, LOOKUP_NORMAL,
-				lhs, rhs, op, lookups, &overload, complain);
-      if (rval)
-	{
-	  if (rval == error_mark_node)
-	    return rval;
-	  suppress_warning (rval /* What warning? */);
-	  if (processing_template_decl)
-	    {
-	      if (overload != NULL_TREE)
-		return (build_min_non_dep_op_overload
-			(MODIFY_EXPR, rval, overload, orig_lhs, orig_rhs));
+      if (overload != NULL_TREE)
+	return (build_min_non_dep_op_overload
+		(MODIFY_EXPR, rval, overload, orig_lhs, orig_rhs));
 
-	      return (build_min_non_dep
-		      (MODOP_EXPR, rval, orig_lhs, op, orig_rhs));
-	    }
-	  return rval;
-	}
+      return (build_min_non_dep
+	      (MODOP_EXPR, rval, orig_lhs, op, orig_rhs));
     }
-  return cp_build_modify_expr (loc, lhs, modifycode, rhs, complain);
+  return rval;
 }
 
 /* Helper function for get_delta_difference which assumes FROM is a base
diff --git a/gcc/testsuite/g++.dg/cpp0x/static_assert15.C b/gcc/testsuite/g++.dg/cpp0x/static_assert15.C
index a740f73fd4a..d5f50d07c91 100644
--- a/gcc/testsuite/g++.dg/cpp0x/static_assert15.C
+++ b/gcc/testsuite/g++.dg/cpp0x/static_assert15.C
@@ -5,6 +5,6 @@ template<int x>
 struct a {
   constexpr void b() {
     int c;
-    static_assert(c %= 1, "");
+    static_assert(c %= 1, ""); // { dg-error "constant" }
   }
 };
diff --git a/gcc/testsuite/g++.dg/expr/unary2.C b/gcc/testsuite/g++.dg/expr/unary2.C
index 5962bfe19c9..4db68375944 100644
--- a/gcc/testsuite/g++.dg/expr/unary2.C
+++ b/gcc/testsuite/g++.dg/expr/unary2.C
@@ -1,9 +1,7 @@
+// PR c++/18474
 // { dg-do compile }
 // Unary plus/minus are not lvalues.
 
-// In templates we require an instantiation to emit the diagnostic. This
-//  is wrong and it is PR 18474.
-
 int n;
 
 void f(void)
@@ -15,6 +13,6 @@ void f(void)
 template <int>
 void g(void)
 {
-  -n = 0;        // { dg-error "lvalue" "" { xfail *-*-* } }
-  +n = 0;        // { dg-error "lvalue" "" { xfail *-*-* } }
+  -n = 0;        // { dg-error "lvalue" "" }
+  +n = 0;        // { dg-error "lvalue" "" }
 }
diff --git a/gcc/testsuite/g++.dg/template/init7.C b/gcc/testsuite/g++.dg/template/init7.C
index bb26c8f92b5..94fc22f578c 100644
--- a/gcc/testsuite/g++.dg/template/init7.C
+++ b/gcc/testsuite/g++.dg/template/init7.C
@@ -6,4 +6,4 @@ template<typename> struct A
   static const int i=0;
 };
 
-template<typename T> const int A<T>::i = 0=0; /* { dg-error "duplicate initialization" } */
+template<typename T> const int A<T>::i = T()=0; /* { dg-error "duplicate initialization" } */
diff --git a/gcc/testsuite/g++.dg/template/non-dependent26.C b/gcc/testsuite/g++.dg/template/non-dependent26.C
new file mode 100644
index 00000000000..1faa39a4b1a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent26.C
@@ -0,0 +1,25 @@
+// Verify non-dependent assignment expressions are recognized as such
+// and are checked ahead of time.
+// PR c++/63198
+// { dg-do compile { target c++11 } }
+
+struct X { using t1 = int; };
+struct Y { X operator=(const Y&); } y;
+template<class T> void f1(decltype(y = y)::t1);
+
+int n;
+template<class T> void f2(decltype(n = n)::t1); // { dg-error "not a class" }
+template<class T> void f3(decltype(n += n)::t1); // { dg-error "not a class" }
+
+template<class T>
+void g() {
+  const int n;
+  n = 42; // { dg-error "read-only" }
+
+  const X x;
+  x = {}; // { dg-error "no match" }
+
+  const Y y;
+  y = {}; // { dg-error "no match" }
+  Y{} = X{}; // { dg-error "no match" }
+}
diff --git a/gcc/testsuite/g++.dg/template/recurse3.C b/gcc/testsuite/g++.dg/template/recurse3.C
index f1db7c5cbca..70c6152d063 100644
--- a/gcc/testsuite/g++.dg/template/recurse3.C
+++ b/gcc/testsuite/g++.dg/template/recurse3.C
@@ -1,14 +1,14 @@
 // PR c++/44609
 // { dg-options -ftemplate-depth=10 }
 
-template<int N>
+template<class T, int N>
 void f()
 {
-  0 = 0;			// { dg-error "lvalue required" }
-  f<N+1>();			// { dg-bogus "instantiation depth" }
+  T(0) = 0;			// { dg-error "lvalue required" }
+  f<T, N+1>();			// { dg-bogus "instantiation depth" }
 }
 
 int main()
 {
-  f<0>();
+  f<int, 0>();
 }
diff --git a/gcc/testsuite/g++.dg/warn/Wparentheses-32.C b/gcc/testsuite/g++.dg/warn/Wparentheses-32.C
new file mode 100644
index 00000000000..719a9d9e73a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wparentheses-32.C
@@ -0,0 +1,28 @@
+// Verify we issue -Wparentheses warnings at template definition time
+// (for suitable non-dependent expressions).
+// { dg-additional-options "-Wparentheses" }
+
+struct X { operator bool(); };
+struct Y { Y& operator=(const Y&); operator bool(); };
+struct Z { int m; operator bool(); };
+
+template<class T>
+void f() {
+  int n, m;
+  if (n = m) { } // { dg-warning "parentheses" }
+
+  X x1, x2;
+  if (x1 = x2) { } // { dg-warning "parentheses" }
+
+  Y y1, y2;
+  if (y1 = y2) { } // { dg-warning "parentheses" }
+
+  Z z1, z2;
+  if (z1 = z2) { } // { dg-warning "parentheses" }
+
+  bool b;
+  b = m = n; // { dg-warning "parentheses" "" { xfail *-*-* } }
+  b = x1 = x2; // { dg-warning "parentheses" "" { xfail *-*-* } }
+  b = y1 = y2; // { dg-warning "parentheses" "" { xfail *-*-* } }
+  b = z1 = z2; // { dg-warning "parentheses" "" { xfail *-*-* } }
+}
diff --git a/libstdc++-v3/testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc
index 720ce96dc28..0d7e667382d 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc
index f378621805f..2ef563038cc 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/independent_bits_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc
index c1cfe9da7fb..071ed75d8d8 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/linear_congruential_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc
index 52476026533..2fb9622fda0 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/mersenne_twister_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc
index 1ca783e3044..3fa9c9ad8d3 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc
index 08beb3bcf93..25d19a0ba66 100644
--- a/libstdc++-v3/testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/26_numerics/random/subtract_with_carry_engine/cons/seed_seq2.cc
@@ -51,7 +51,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
diff --git a/libstdc++-v3/testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc b/libstdc++-v3/testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc
index b629053585e..fe798f2f05b 100644
--- a/libstdc++-v3/testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc
+++ b/libstdc++-v3/testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/seed_seq2.cc
@@ -52,7 +52,7 @@ struct seed_seq
   // T is convertible to the engine's result_type:
   operator T() const noexcept { return T(); }
 
-  bool called = false;
+  mutable bool called = false;
 };
 
 using engine_type
-- 
2.42.0.216.gbda494f404


  reply	other threads:[~2023-09-18 13:12 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-17 18:51 Patrick Palka
2023-09-18  3:01 ` Jason Merrill
2023-09-18 13:12   ` Patrick Palka [this message]
2023-09-18 13:33     ` Jason Merrill

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