fix segfault on macro not found

gcc/rust/expand/rust-macro-expand.cc

@@ -40,7 +40,14 @@ MacroExpander::expand_decl_macro (location_t invoc_locus,
 {
   // ensure that both invocation and rules are in a valid state
   rust_assert (!invoc.is_marked_for_strip ());
-  rust_assert (!rules_def.is_marked_for_strip ());
+  /* Note: We can't safely check if rules_def is marked for strip here because
+   * rules_def might be a dangling pointer to a deleted macro definition.
+   * This can happen when a macro definition has an invalid attribute (such as
+   * #[x] where x is not an attribute macro), causing the item to be deleted
+   * during attribute processing, but the pointer in in the invocation map still
+   * exists.
+   */
+  // rust_assert (!rules_def.is_marked_for_strip ());
   rust_assert (rules_def.get_macro_rules ().size () > 0);
 
   /* probably something here about parsing invoc and rules def token trees to
@@ -314,6 +321,9 @@ MacroExpander::expand_invoc (AST::MacroInvocation &invoc,
 
   auto rdef = rules_def.value ();
 
+  if (!rdef)
+    return;
+
   // We store the last expanded invocation and macro definition for error
   // reporting in case the recursion limit is reached
   last_invoc = *invoc.clone_macro_invocation_impl ();

gcc/rust/util/rust-hir-map.cc

@@ -911,6 +911,10 @@ Mappings::insert_macro_invocation (AST::MacroInvocation &invoc,
   auto it = macroInvocations.find (invoc.get_macro_node_id ());
   rust_assert (it == macroInvocations.end ());
 
+  // Don't insert null pointers into the map as it could segfault later
+  if (!def)
+    return;
+
   macroInvocations[invoc.get_macro_node_id ()] = def;
 }
 

gcc/testsuite/rust/compile/issue-4187-1.rs

@@ -0,0 +1,29 @@
+macro x(
+    $macro_name:ident,
+    $macro2_name:ident,
+    $type_name:ident,
+    $field_name:ident,
+    $const_name:ident
+) {
+    pub struct $type_name {}
+
+    pub const $const_name: $type_name = $type_name {};
+
+    #[x]
+    // { dg-error "macro not found" "" { target *-*-* } .-1 }
+    macro_rules! $macro_name {
+        () => {};
+    }
+
+    pub macro $type_name {
+                    (Copy $e:expr) => {},
+                    () => {;},
+
+                }
+}
+
+x!(test_fields, test_fields2, x, field, MY_CONST);
+
+pub fn check_fields_local() {
+    test_fields!(check_fields); // { dg-error "Failed to match any rule within macro" }
+}

gcc/testsuite/rust/compile/issue-4187-2.rs

@@ -0,0 +1,32 @@
+macro x(
+    $macro_name:ident,
+    $macro2_name:ident,
+    $type_name:ident,
+    $field_name:ident,
+    $const_name:ident
+) {
+    pub struct $type_name {}
+
+    pub const $const_name: $type_name = $type_name {};
+
+    #[x]
+    // { dg-error "macro not found" "" { target *-*-* } .-1 }
+    macro_rules! $macro_name {
+        (check_fields) => {{
+            assert_eq!($const_name.field, Field::MacroCtxt);
+        }};
+    }
+
+    pub macro $type_name {
+                (Copy $e:expr) => {},
+                (check_fields) => {test_fields!(check_fields);},
+
+            }
+}
+
+x!(test_fields, test_fields2, x, field, MY_CONST);
+
+pub fn check_fields_local() {
+    test_fields!(check_fields); // { dg-error "Failed to match any rule within macro" }
+    test_fields2!(check_fields); // { dg-error "could not resolve macro invocation" }
+}