AstGen: detect declarations shadowing locals

Closes #9355

1 files changed, 22 insertions, 0 deletions

diff --git a/test/cases/compile_errors/decl_shadows_local.zig b/test/cases/compile_errors/decl_shadows_local.zig
new file mode 100644
index 0000000000..cb48cafa45
--- /dev/null
+++ b/test/cases/compile_errors/decl_shadows_local.zig
@@ -0,0 +1,22 @@
+fn foo(a: usize) void {
+    struct {
+        const a = 1;
+    };
+}
+fn bar(a: usize) void {
+    struct {
+        const b = struct {
+            const a = 1;
+        };
+    };
+    _ = a;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:15: error: redeclaration of function parameter 'a'
+// :1:8: note: previous declaration here
+// :9:19: error: redeclaration of function parameter 'a'
+// :6:8: note: previous declaration here