[gcc r17-1074] gccrs: Fix ICE in get_function_expr when cfg'd return type inside macro

[Arthur Cohen via Gcc-cvs]

https://gcc.gnu.org/g:ba972b2b2ecdbe22ab2132fa7f696a8b037bbb77

commit r17-1074-gba972b2b2ecdbe22ab2132fa7f696a8b037bbb77
Author: Harishankar <harishankar...@gmail.com>
Date:   Fri Apr 17 15:08:48 2026 +0530

    gccrs: Fix ICE in get_function_expr when cfg'd return type inside macro
    
    the problem is cfg-strip emits an error for unstrippable expressions but
    doesn't mark the parent for strip, leaving a broken subtree for later
    passes to ICE on.
    
    gcc/rust/ChangeLog:
    
            * expand/rust-cfg-strip.cc (CfgStrip::visit): mark CallExpr for
            strip when function expression fails stripping.
            (CfgStrip::visit): mark ArrayIndexExpr for strip when array or
            index expression fails stripping.
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/issue-4167.rs: New test.
    
    Signed-off-by: Harishankar <harishankar...@gmail.com>

Diff:
---
 gcc/rust/expand/rust-cfg-strip.cc        | 20 ++++++++++++++------
 gcc/testsuite/rust/compile/issue-4167.rs | 15 +++++++++++++++
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/gcc/rust/expand/rust-cfg-strip.cc 
b/gcc/rust/expand/rust-cfg-strip.cc
index 2e6971e63f32..67baebec158d 100644
--- a/gcc/rust/expand/rust-cfg-strip.cc
+++ b/gcc/rust/expand/rust-cfg-strip.cc
@@ -828,9 +828,13 @@ CfgStrip::visit (AST::ArrayIndexExpr &expr)
 
   const auto &array_expr = expr.get_array_expr ();
   if (array_expr.is_marked_for_strip ())
-    rust_error_at (array_expr.get_locus (),
-                  "cannot strip expression in this position - outer "
-                  "attributes not allowed");
+    {
+      rust_error_at (array_expr.get_locus (),
+                    "cannot strip expression in this position - outer "
+                    "attributes not allowed");
+      expr.mark_for_strip ();
+      return;
+    }
 
   const auto &index_expr = expr.get_index_expr ();
   if (index_expr.is_marked_for_strip ())
@@ -1044,9 +1048,13 @@ CfgStrip::visit (AST::CallExpr &expr)
 
   auto &function = expr.get_function_expr ();
   if (function.is_marked_for_strip ())
-    rust_error_at (function.get_locus (),
-                  "cannot strip expression in this position - outer "
-                  "attributes not allowed");
+    {
+      rust_error_at (function.get_locus (),
+                    "cannot strip expression in this position - outer "
+                    "attributes not allowed");
+      expr.mark_for_strip ();
+      return;
+    }
 
   /* spec says outer attributes are specifically allowed for elements
    * of call expressions, so full stripping possible */
diff --git a/gcc/testsuite/rust/compile/issue-4167.rs 
b/gcc/testsuite/rust/compile/issue-4167.rs
new file mode 100644
index 000000000000..47f4e88ea7c7
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-4167.rs
@@ -0,0 +1,15 @@
+#![feature(no_core)]
+#![no_core]
+macro_rules! the_macro {
+    ( $foo:stmt ; $bar:stmt ; ) => {
+        #[cfg(foo)]
+        $foo
+
+        $foo[cfg(bar)]
+        $bar
+    };
+}
+
+fn the_function() {
+    the_macro!( (); (); ); // { dg-error "cannot strip expression in this 
position" }
+}