From: Patrick Palka <ppalka@redhat.com>
Date: Thu, 29 Jun 2023 20:02:04 +0000 (-0400)
Subject: c++: unpropagated CONSTRUCTOR_MUTABLE_POISON [PR110463]
X-Git-Tag: basepoints/gcc-15~7941
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fd8a1be04d4cdbfefea457b99ed8404d77b35dd6;p=thirdparty%2Fgcc.git

c++: unpropagated CONSTRUCTOR_MUTABLE_POISON [PR110463]

Here we're incorrectly accepting the mutable member accesses because
cp_fold neglects to propagate CONSTRUCTOR_MUTABLE_POISON when folding a
CONSTRUCTOR.

	PR c++/110463

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold) <case CONSTRUCTOR>: Propagate
	CONSTRUCTOR_MUTABLE_POISON.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/constexpr-mutable6.C: New test.
---

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 853b1e442363..f57341977748 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -3079,6 +3079,8 @@ cp_fold (tree x, fold_flags_t flags)
 	    x = build_constructor (TREE_TYPE (x), nelts);
 	    CONSTRUCTOR_PLACEHOLDER_BOUNDARY (x)
 	      = CONSTRUCTOR_PLACEHOLDER_BOUNDARY (org_x);
+	    CONSTRUCTOR_MUTABLE_POISON (x)
+	      = CONSTRUCTOR_MUTABLE_POISON (org_x);
 	  }
 	if (VECTOR_TYPE_P (TREE_TYPE (x)))
 	  x = fold (x);
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
new file mode 100644
index 000000000000..2c946e388ab4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
@@ -0,0 +1,18 @@
+// PR c++/110463
+// { dg-do compile { target c++11 } }
+
+struct U {
+  mutable int x = 1;
+};
+
+struct V {
+  mutable int y = 1+1;
+};
+
+int main() {
+  constexpr U u = {};
+  constexpr int x = u.x; // { dg-error "mutable" }
+
+  constexpr V v = {};
+  constexpr int y = v.y; // { dg-error "mutable" }
+}