Generate error for const trait functions

Fixes issue #2040 Error is produced if a trait function is declared const. gcc/rust/ChangeLog: * typecheck/rust-hir-type-check-implitem.cc (TypeCheckImplItemWithTrait::visit): Produce error if trait funtion is found to be const. gcc/testsuite/ChangeLog: * rust/compile/issue-2040.rs: New test. Signed-off-by: Nobel Singh <[email protected]>
Rust-GCC · Nov 22, 2023 · 5450f98 · 5450f98
1 parent 50fe556
commit 5450f98
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diff --git a/gcc/rust/typecheck/rust-hir-type-check-implitem.cc b/gcc/rust/typecheck/rust-hir-type-check-implitem.cc
@@ -520,6 +520,12 @@ TypeCheckImplItemWithTrait::visit (HIR::Function &function)
 		     trait_reference.get_name ().c_str ());
       return;
     }
+  // const function as trait item
+  if (function.get_qualifiers ().is_const ())
+    {
+      rust_error_at (function.get_locus (), ErrorCode::E0379,
+		     "functions in traits cannot be declared const");
+    }
 
   // get the item from the predicate
   resolved_trait_item = trait_reference.lookup_associated_item (raw_trait_item);

diff --git a/gcc/testsuite/rust/compile/issue-2040.rs b/gcc/testsuite/rust/compile/issue-2040.rs
@@ -0,0 +1,12 @@
+trait Foo {
+    fn f() -> u32;
+}
+
+impl Foo for u32 {
+    const fn f() -> u32 { 
+        // { dg-error "functions in traits cannot be declared const" "" { target *-*-* } .-1 }
+        22 
+    } 
+}
+
+fn main() { }