[gcc r13-3163] c++ modules: static var in inline function [PR104433]

[Patrick Palka <ppalka@gcc.gnu.org>]

https://gcc.gnu.org/g:edbb2551d156d69a2e337dcd8daa69f2680d57ea

commit r13-3163-gedbb2551d156d69a2e337dcd8daa69f2680d57ea
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Oct 7 09:32:45 2022 -0400

    c++ modules: static var in inline function [PR104433]
    
    The below testcase fails to link with the error
    
      undefined reference to `f()::y'
    
    ultimately because during stream out for the static VAR_DECL y we
    override DECL_EXTERNAL to true, which later during IPA confuses
    symbol_table::remove_unreachable_nodes into thinking it's safe
    to not emit the symbol.
    
    The streaming code here already avoids overriding DECL_EXTERNAL for
    inline vars and functions, so it seems natural to extend this to
    static vars from an inline function.
    
            PR c++/104433
    
    gcc/cp/ChangeLog:
    
            * module.cc (trees_out::core_bools): Don't override
            DECL_EXTERNAL to true for static variables from an inline
            function.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/modules/static-2_a.H: New test.
            * g++.dg/modules/static-2_b.C: New test.

Diff:
---
 gcc/cp/module.cc                          | 3 +++
 gcc/testsuite/g++.dg/modules/static-2_a.H | 8 ++++++++
 gcc/testsuite/g++.dg/modules/static-2_b.C | 9 +++++++++
 3 files changed, 20 insertions(+)

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index c5eff219909..cb1929bc5d5 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -5411,6 +5411,9 @@ trees_out::core_bools (tree t)
 
 	    case VAR_DECL:
 	      if (TREE_PUBLIC (t)
+		  && !(TREE_STATIC (t)
+		       && DECL_FUNCTION_SCOPE_P (t)
+		       && DECL_DECLARED_INLINE_P (DECL_CONTEXT (t)))
 		  && !DECL_VAR_DECLARED_INLINE_P (t))
 		is_external = true;
 	      break;
diff --git a/gcc/testsuite/g++.dg/modules/static-2_a.H b/gcc/testsuite/g++.dg/modules/static-2_a.H
new file mode 100644
index 00000000000..65c7619616b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/static-2_a.H
@@ -0,0 +1,8 @@
+// PR c++/104433
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+inline int* f() {
+  static int y;
+  return &y;
+}
diff --git a/gcc/testsuite/g++.dg/modules/static-2_b.C b/gcc/testsuite/g++.dg/modules/static-2_b.C
new file mode 100644
index 00000000000..bfd35b0fc15
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/static-2_b.C
@@ -0,0 +1,9 @@
+// PR c++/104433
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+
+import "static-2_a.H";
+
+int main() {
+  f();
+}