[gcc r13-10062] d: Fix internal compiler error: in visit, at d/decl.cc:838 [PR119799]

[Iain Buclaw]

https://gcc.gnu.org/g:7cd6ed0768932b7776c41c70ca0145d6b8c17cc4

commit r13-10062-g7cd6ed0768932b7776c41c70ca0145d6b8c17cc4
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Wed Jan 28 23:51:35 2026 +0100

    d: Fix internal compiler error: in visit, at d/decl.cc:838 [PR119799]
    
    This was caused by a check in the D front-end disallowing static
    VAR_DECLs with a size `0'.
    
    While empty structs in D are give the size `1', the same symbol coming
    from ImportC modules do infact have no size, so allow C variables to
    pass the check as well as array objects.
    
            PR d/119799
    
    gcc/d/ChangeLog:
    
            * decl.cc (DeclVisitor::visit (VarDeclaration *)): Check front-end
            type size before building the VAR_DECL.  Allow C symbols to have a
            size of `0'.
    
    gcc/testsuite/ChangeLog:
    
            * gdc.dg/torture/pr119799.d: New test.
            * gdc.dg/torture/imports/pr119799c.c: New test.
    
    (cherry picked from commit 074b2b0f91f948fe3488ada91ec6a8576c684dea)

Diff:
---
 gcc/d/decl.cc                                    | 15 ++++++++++-----
 gcc/testsuite/gdc.dg/torture/imports/pr119799c.c |  4 ++++
 gcc/testsuite/gdc.dg/torture/pr119799.d          |  9 +++++++++
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/gcc/d/decl.cc b/gcc/d/decl.cc
index 945f075cd44e..58097925468c 100644
--- a/gcc/d/decl.cc
+++ b/gcc/d/decl.cc
@@ -781,6 +781,12 @@ public:
       }
     else if (d->isDataseg ())
       {
+	/* When the front-end type size is invalid, an error has already been
+	   given for the declaration or type.  */
+	dinteger_t size = d->type->size (d->loc);
+	if (size == SIZE_INVALID)
+	  return;
+
 	tree decl = get_symbol_decl (d);
 
 	/* Only need to build the VAR_DECL for extern declarations.  */
@@ -794,9 +800,7 @@ public:
 	  return;
 
 	/* How big a symbol can be should depend on back-end.  */
-	tree size = build_integer_cst (d->type->size (d->loc),
-				       build_ctype (Type::tsize_t));
-	if (!valid_constant_size_p (size))
+	if (!valid_constant_size_p (build_integer_cst (size, size_type_node)))
 	  {
 	    error_at (make_location_t (d->loc), "size is too large");
 	    return;
@@ -824,8 +828,9 @@ public:
 	  }
 
 	/* Frontend should have already caught this.  */
-	gcc_assert (!integer_zerop (size)
-		    || d->type->toBasetype ()->isTypeSArray ());
+	gcc_assert ((size != 0 && size != SIZE_INVALID)
+		    || d->type->toBasetype ()->isTypeSArray ()
+		    || d->isCsymbol ());
 
 	d_finish_decl (decl);
 
diff --git a/gcc/testsuite/gdc.dg/torture/imports/pr119799c.c b/gcc/testsuite/gdc.dg/torture/imports/pr119799c.c
new file mode 100644
index 000000000000..0a97a772c8f7
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/imports/pr119799c.c
@@ -0,0 +1,4 @@
+inline void fn119799()
+{
+    static struct {} s119799;
+}
diff --git a/gcc/testsuite/gdc.dg/torture/pr119799.d b/gcc/testsuite/gdc.dg/torture/pr119799.d
new file mode 100644
index 000000000000..f66aee8234d4
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr119799.d
@@ -0,0 +1,9 @@
+// { dg-do compile }
+// { dg-additional-files "imports/pr119799c.c" }
+// { dg-additional-options "-I[srcdir]" }
+import imports.pr119799c;
+
+void test()
+{
+    fn119799;
+}