Not possible to alias or take reference for extension methods on non-user defined types. #1637

releasenotes.md

@@ -19,6 +19,7 @@
 - Fix issue with properties in different targets not being respected #1633.
 - Indexing an Optional slice would crash in codegen #1636.
 - SimpleHeapAllocator bug when splitting blocks allowed memory overrun.
+- Not possible to alias or take reference for extension methods on non-user defined types. #1637
 
 ### Stdlib changes
 - Add `io::MultiReader`, `io::MultiWriter`, and `io::TeeReader` structs.

src/compiler/sema_expr.c

@@ -3641,6 +3641,34 @@ static inline bool sema_analyse_macro_func_access(SemaContext *context, Expr *ex
 	return sema_expr_analyse_type_access(context, expr, parent->type, identifier, missing_ref);
 }
 
+static inline Decl *sema_check_for_type_method(SemaContext *context, Expr *expr, Type *parent_type, const char *name, bool *missing_ref)
+{
+	ASSERT0(parent_type == parent_type->canonical);
+	Decl *ambiguous = NULL;
+	Decl *private = NULL;
+	Decl *member = sema_resolve_type_method(context->unit, parent_type, name, &ambiguous, &private);
+	if (private)
+	{
+		if (missing_ref)
+		{
+			*missing_ref = true;
+		}
+		else
+		{
+			SEMA_ERROR(expr, "The method '%s' has private visibility.", name);
+		}
+		return poisoned_decl;
+	}
+	if (ambiguous)
+	{
+		SEMA_ERROR(expr, "'%s' is an ambiguous name and so cannot be resolved, "
+		                 "it may refer to method defined in '%s' or one in '%s'",
+		           name, member->unit->module->name->module, ambiguous->unit->module->name->module);
+		return poisoned_decl;
+	}
+	return member;
+}
+
 static inline bool sema_expr_analyse_type_access(SemaContext *context, Expr *expr, Type *parent_type, Expr *identifier, bool *missing_ref)
 {
 	ASSERT_SPAN(expr, identifier->expr_kind == EXPR_IDENTIFIER);
@@ -3659,9 +3687,16 @@ static inline bool sema_expr_analyse_type_access(SemaContext *context, Expr *exp
 
 	if (!type_may_have_sub_elements(canonical))
 	{
-		if (missing_ref) goto MISSING_REF;
-		SEMA_ERROR(expr, "'%s' does not have a property '%s'.", type_to_error_string(parent_type), name);
-		return false;
+		Decl *member = sema_check_for_type_method(context, expr, parent_type->canonical, name, missing_ref);
+		if (!decl_ok(member)) return false;
+		if (!member)
+		{
+			if (missing_ref) goto MISSING_REF;
+			RETURN_SEMA_ERROR(expr, "'%s' does not have a property or method '%s'.", type_to_error_string(parent_type), name);
+		}
+		expr->expr_kind = EXPR_IDENTIFIER;
+		expr_resolve_ident(expr, member);
+		return true;
 	}
 	Decl *decl = canonical->decl;
 	if (!decl_ok(decl)) return false;
@@ -3704,26 +3739,12 @@ static inline bool sema_expr_analyse_type_access(SemaContext *context, Expr *exp
 			UNREACHABLE
 	}
 
-
 	Decl *member = sema_decl_stack_find_decl_member(context, decl, name);
 	if (!decl_ok(member)) return false;
 	if (!member)
 	{
-		Decl *ambiguous = NULL;
-		Decl *private = NULL;
-		member = sema_resolve_type_method(context->unit, decl->type, name, &ambiguous, &private);
-		if (private)
-		{
-			if (missing_ref) goto MISSING_REF;
-			SEMA_ERROR(expr, "The method '%s' has private visibility.", name);
-			return false;
-		}
-		if (ambiguous)
-		{
-			RETURN_SEMA_ERROR(expr, "'%s' is an ambiguous name and so cannot be resolved, "
-									"it may refer to method defined in '%s' or one in '%s'",
-					   name, member->unit->module->name->module, ambiguous->unit->module->name->module);
-		}
+		member = sema_check_for_type_method(context, expr, decl->type, name, missing_ref);
+		if (!decl_ok(member)) return false;
 	}
 	if (!member)
 	{

test/test_suite/compile_time_introspection/nameof_err.c3

@@ -11,7 +11,7 @@ fn void main2()
 
 fn void main3()
 {
-    $evaltype("int").extnameof; // #error: 'int' does not have a property 'extnameof'
+    $evaltype("int").extnameof; // #error: 'int' does not have a property or method 'extnameof'
 }
 
 fn void main4()

test/test_suite/compile_time_introspection/sizeof_errors.c3

@@ -29,12 +29,12 @@ fn void g()
 
 fn void k()
 {
-    int v = $evaltype("int").x.sizeof; // #error: 'int' does not have a property 'x'.
+    int v = $evaltype("int").x.sizeof; // #error: 'x'.
 }
 
 fn void l()
 {
-    int v = $sizeof(int[].len); // #error:  'int[]' does not have a property 'len'
+    int v = $sizeof(int[].len); // #error: 'len'
 }
 
 fn void m()

test/test_suite/methods/method_ref_for_extension_method.c3

@@ -0,0 +1,19 @@
+module testc3;
+import std::io;
+
+struct Foo {
+  int i;
+}
+
+fn bool Foo[].is_empty(Foo[] array) {
+  return array.len == 0;
+}
+
+def foo_arr_is_empty = Foo[].is_empty;
+
+fn void main() {
+  Foo[] foos = { Foo { .i = 0 } };
+  void* foo = &Foo[].is_empty;
+  io::printfn("Is empty: %s", foos.is_empty());
+  io::printfn("Is empty: %s", foo_arr_is_empty(foos));
+}