From: Nathaniel Shead <nathanieloshead@gmail.com>
Date: Wed, 28 Feb 2024 00:20:53 +0000 (+1100)
Subject: c++: Revert deferring emission of inline variables [PR114013]
X-Git-Tag: basepoints/gcc-15~938
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=615b62aada6cc42759e5c43e196dab6c524925d6;p=thirdparty%2Fgcc.git

c++: Revert deferring emission of inline variables [PR114013]

This is a (partial) reversion of r14-8987-gdd9d14f7d53 to return to
eagerly emitting inline variables to the middle-end when they are
declared. 'import_export_decl' will still continue to accept them, as
allowing this is a pure extension and doesn't seem to cause issues with
modules, but otherwise deferring the emission of inline variables
appears to cause issues on some targets and prevents some code using
inline variable templates from correctly linking.

There might be a more targetted way to support this, but due to the
complexity of handling linkage and emission I'd prefer to wait till
GCC 15 to explore our options.

	PR c++/113970
	PR c++/114013

gcc/cp/ChangeLog:

	* decl.cc (make_rtl_for_nonlocal_decl): Don't defer inline
	variables.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/inline-var10.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index e47f694e4e56..d19d09adde43 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -7954,10 +7954,6 @@ make_rtl_for_nonlocal_decl (tree decl, tree init, const char* asmspec)
       && DECL_IMPLICIT_INSTANTIATION (decl))
     defer_p = 1;
 
-  /* Defer vague-linkage variables.  */
-  if (DECL_INLINE_VAR_P (decl))
-    defer_p = 1;
-
   /* If we're not deferring, go ahead and assemble the variable.  */
   if (!defer_p)
     rest_of_decl_compilation (decl, toplev, at_eof);
diff --git a/gcc/testsuite/g++.dg/cpp1z/inline-var10.C b/gcc/testsuite/g++.dg/cpp1z/inline-var10.C
new file mode 100644
index 000000000000..8a198556778f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/inline-var10.C
@@ -0,0 +1,33 @@
+// PR c++/114013
+// { dg-do link { target c++17 } }
+
+struct S { int a, b; };
+
+template <int N>
+constexpr struct S var[8] = {};
+
+template <>
+constexpr inline struct S var<6>[8] = {
+  { 1, 1 }, { 2, 0 }, { 3, 1 }, { 4, 0 },
+  { 5, 1 }, { 6, 0 }, { 7, 1 }, { 8, 0 }
+};
+
+[[gnu::noipa]] void
+foo (S)
+{
+}
+
+template <int N>
+void
+bar (int x)
+{
+  foo (var<N>[x]);
+}
+
+volatile int x;
+
+int
+main ()
+{
+  bar <6> (x);
+}