[gcc r15-10905] c: Call relayout_decl in build_compound_literal when completing type [PR123365]

[Jakub Jelinek]

https://gcc.gnu.org/g:7cc3f2a6b56bff19384e489a4f1c294dab775e09

commit r15-10905-g7cc3f2a6b56bff19384e489a4f1c294dab775e09
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Feb 18 17:46:38 2026 +0100

    c: Call relayout_decl in build_compound_literal when completing type [PR123365]
    
    Most other spots inthe C FE which change type of some VAR_DECL
    through complete_array_type call relayout_decl to fix up DECL_MODE
    etc., but build_compound_literal strangely does not.
    
    It has layout_decl (decl, 0); call later on but I think that is
    quite useless given that already the build_decl call earlier
    calls that and so the second layout_decl probably does nothing
    most of the time.
    
    On the following testcase, the compound literal VAR_DECL has
    BLKmode from the time it had incomplete array type and isn't
    changed to DImode that the completed type has and asm stmt
    expansion is unhappy about that.
    
    Fixed thusly.
    
    2026-02-18  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/123365
            * c-decl.cc (build_compound_literal): Call relayout_decl
            after completing the type.
    
            * gcc.c-torture/compile/pr123365.c: New test.
    
    (cherry picked from commit 319db4667fbed5180a1ecc687ff8556d2447760a)

Diff:
---
 gcc/c/c-decl.cc                                | 1 +
 gcc/testsuite/gcc.c-torture/compile/pr123365.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index 045f03998f63..80f9a59ff818 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -6539,6 +6539,7 @@ build_compound_literal (location_t loc, tree type, tree init, bool non_const,
 
       type = TREE_TYPE (decl);
       TREE_TYPE (DECL_INITIAL (decl)) = type;
+      relayout_decl (decl);
     }
 
   if (type == error_mark_node || !COMPLETE_TYPE_P (type))
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr123365.c b/gcc/testsuite/gcc.c-torture/compile/pr123365.c
new file mode 100644
index 000000000000..b1073634df24
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr123365.c
@@ -0,0 +1,7 @@
+/* PR c/123365 */
+
+void
+foo ()
+{
+  __asm__ volatile ("" : "+r" ((long long[]) { 0 }));
+}