On 9/17/24 10:30 PM, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/14?
OK.
-- >8 --
The result of build_fold_indirect_ref can be a COMPONENT_REF in
which case using DECL_SOURCE_LOCATION will crash. Look at its op1
instead.
PR c++/116741
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_constant_expression) <case CONVERT_EXPR>: If
the result of build_fold_indirect_ref is a COMPONENT_REF, use its op1.
Check DECL_P before calling inform.
gcc/testsuite/ChangeLog:
* g++.dg/cpp26/constexpr-voidptr4.C: New test.
---
gcc/cp/constexpr.cc | 7 +++--
.../g++.dg/cpp26/constexpr-voidptr4.C | 29 +++++++++++++++++++
2 files changed, 34 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp26/constexpr-voidptr4.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index c3668b0d7d3..f6fd059be46 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -8201,8 +8201,11 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx,
tree t,
TREE_TYPE (op), TREE_TYPE (TREE_TYPE (sop)),
TREE_TYPE (type));
tree obj = build_fold_indirect_ref (sop);
- inform (DECL_SOURCE_LOCATION (obj),
- "pointed-to object declared here");
+ if (TREE_CODE (obj) == COMPONENT_REF)
+ obj = TREE_OPERAND (obj, 1);
+ if (DECL_P (obj))
+ inform (DECL_SOURCE_LOCATION (obj),
+ "pointed-to object declared here");
}
*non_constant_p = true;
return t;
diff --git a/gcc/testsuite/g++.dg/cpp26/constexpr-voidptr4.C
b/gcc/testsuite/g++.dg/cpp26/constexpr-voidptr4.C
new file mode 100644
index 00000000000..53563c928f2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/constexpr-voidptr4.C
@@ -0,0 +1,29 @@
+// PR c++/116741
+// { dg-do compile { target c++26 } }
+
+struct S {
+ int foo; // { dg-message "pointed-to object" }
+};
+
+struct S2 {
+ int foo; // { dg-message "pointed-to object" }
+};
+
+struct X {
+ S2 s;
+};
+
+constexpr float f1() {
+ S s;
+ void* p = &s.foo;
+ return *static_cast<float*>(p); // { dg-error "not allowed in a constant
expression" }
+}
+
+constexpr float f2() {
+ X x;
+ void* p = &x.s.foo;
+ return *static_cast<float*>(p); // { dg-error "not allowed in a constant
expression" }
+}
+
+constexpr auto x1 = f1();
+constexpr auto x2 = f2();
base-commit: dfe0d4389a3ce43179563a63046ad3e74d615a08
