[gcc r16-7120] d: Fix ICE: in expand_asm_stmt, at cfgexpand.cc:3445 [PR121477]

[Iain Buclaw]

https://gcc.gnu.org/g:baaa412ae73c12e2e5ea2552534ec42525f6d21e

commit r16-7120-gbaaa412ae73c12e2e5ea2552534ec42525f6d21e
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Wed Jan 28 18:34:21 2026 +0100

    d: Fix ICE: in expand_asm_stmt, at cfgexpand.cc:3445 [PR121477]
    
    The d_mark_addressable routine that sets TREE_ADDRESSABLE in the D
    front-end did not handle DECL_BIT_FIELD.
    
            PR d/121477
    
    gcc/d/ChangeLog:
    
            * d-codegen.cc (d_mark_addressable): Give an error if taking the
            address of a DECL_BIT_FIELD.
    
    gcc/testsuite/ChangeLog:
    
            * gdc.dg/pr121477.d: New test.

Diff:
---
 gcc/d/d-codegen.cc              |  6 +++++-
 gcc/testsuite/gdc.dg/pr121477.d | 12 ++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/d/d-codegen.cc b/gcc/d/d-codegen.cc
index 716fa447eba1..9ec23546b4ad 100644
--- a/gcc/d/d-codegen.cc
+++ b/gcc/d/d-codegen.cc
@@ -745,8 +745,12 @@ d_mark_addressable (tree exp, bool complain)
 {
   switch (TREE_CODE (exp))
     {
-    case ADDR_EXPR:
     case COMPONENT_REF:
+      if (complain && DECL_BIT_FIELD (TREE_OPERAND (exp, 1)))
+	error ("cannot take address of bit-field %qD", TREE_OPERAND (exp, 1));
+
+      /* Fall through.  */
+    case ADDR_EXPR:
     case ARRAY_REF:
     case REALPART_EXPR:
     case IMAGPART_EXPR:
diff --git a/gcc/testsuite/gdc.dg/pr121477.d b/gcc/testsuite/gdc.dg/pr121477.d
new file mode 100644
index 000000000000..3f5bc359272e
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr121477.d
@@ -0,0 +1,12 @@
+// { dg-do compile }
+// { dg-additional-options "-fpreview=bitfields" }
+struct S121477
+{
+    int x : 4;
+}
+
+void f121477(S121477 s)
+{
+    asm {"%0" :: "m" (s.x); } // { dg-error "cannot take address of bit-field" }
+    asm {"%0" : "=m" (s.x); } // { dg-error "cannot take address of bit-field" }
+}