From 352c21c8a22a48d34cbd2fbfe398ee12c0a1d681 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Mon, 5 Aug 2024 15:04:05 -0400
Subject: [PATCH] c++: zero-init and class nttp [PR94568]
A zero-initializer should not reflect the constness of what it's
initializing, as it does not for initializers with different syntax.
This does have mangling implications for rare C++20 code, but it seems
infeasable to make the mangling depend on -fabi-version while fixing the
semantic bug, and C++20 is still experimental anyway.
PR c++/94568
gcc/cp/ChangeLog:
* init.cc (build_zero_init_1): Call cv_unqualified.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/nontype-class36.C: Remove xfail.
* g++.dg/cpp2a/nontype-class37.C: Remove xfail.
* g++.dg/cpp1z/nontype-auto26.C: New test.
---
gcc/cp/init.cc | 3 ++
gcc/testsuite/g++.dg/cpp1z/nontype-auto26.C | 29 ++++++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/nontype-class36.C | 2 +-
gcc/testsuite/g++.dg/cpp2a/nontype-class37.C | 2 +-
4 files changed, 34 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/nontype-auto26.C
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index de82152bd1d3..20373d269882 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -173,6 +173,9 @@ build_zero_init_1 (tree type, tree nelts, bool static_storage_p,
gcc_assert (nelts == NULL_TREE || TREE_CODE (nelts) == INTEGER_CST);
+ /* An initializer is unqualified. */
+ type = cv_unqualified (type);
+
if (type == error_mark_node)
;
else if (static_storage_p && zero_init_p (type))
diff --git a/gcc/testsuite/g++.dg/cpp1z/nontype-auto26.C b/gcc/testsuite/g++.dg/cpp1z/nontype-auto26.C
new file mode 100644
index 000000000000..9abe54ed9745
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/nontype-auto26.C
@@ -0,0 +1,29 @@
+// PR c++/94568
+// { dg-do compile { target c++20 } }
+
+struct A;
+typedef int A::*MemPtr;
+
+struct B { MemPtr p; };
+
+static constexpr MemPtr mp { };
+
+template <B> struct X { };
+
+typedef X<B{{MemPtr{ }}}> XB;
+typedef X<B{{mp}}> XB;
+
+struct C { int a[2]; };
+template <C> struct D { };
+
+constexpr const int i0 = 0;
+constexpr const int i_{ };
+
+static_assert (i0 == i_);
+
+// typedef D<C{ { 0, 1 } }> DC01;
+// typedef D<C{ { i0, 1 } }> DC01;
+typedef D<C{ { i_, 1 } }> DC01;
+
+// { dg-final { scan-assembler "_Z1f1DIXtl1CtlA2_iLi0ELi1EEEEE" } }
+void f(DC01) {}
diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class36.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class36.C
index 8371eb96621f..2e6d76cd43af 100644
--- a/gcc/testsuite/g++.dg/cpp2a/nontype-class36.C
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class36.C
@@ -59,7 +59,7 @@ typedef X<B{ nullptr, nullptr, mpi }> XB00p;
typedef X<B{ MemPtr{ }, MemPtr{ }, mpi }> XB00p;
typedef X<B{ mp0, MemPtr{ }, mpi }> XB00p;
typedef X<B{ mpn, mpn, mpi }> XB00p;
-typedef X<B{ mpn, mp_, mpi }> XB00p; // { dg-bogus "conflicting declaration" "pr94568" { xfail *-*-* } }
+typedef X<B{ mpn, mp_, mpi }> XB00p; // { dg-bogus "conflicting declaration" "pr94568" }
static const constexpr MemFuncPtr mfp0 = { 0 };
static const constexpr MemFuncPtr mfpn = { nullptr };
diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class37.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class37.C
index f5e9826d2431..dc054a9939aa 100644
--- a/gcc/testsuite/g++.dg/cpp2a/nontype-class37.C
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class37.C
@@ -77,4 +77,4 @@ typedef D<C{ { 0, 1 } }> DC01;
typedef D<C{ { 0, 1, 0 } }> DC01;
typedef D<C{ { 0, 1, 0, 0 } }> DC01;
typedef D<C{ { 0, i1, 0, 0 } }> DC01;
-typedef D<C{ { i0, i1, i0, i0 } }> DC01; // { dg-bogus "conflicting declaration" "pr94567" { xfail *-*-* } }
+typedef D<C{ { i0, i1, i0, i0 } }> DC01; // { dg-bogus "conflicting declaration" "pr94568" }
--
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