- Improve error message for Foo{} when Foo is not a generic type #2574.

releasenotes.md

@@ -11,6 +11,7 @@
 - Enums now work with `membersof` to return the associated values. #2571
 - Deprecated `SomeEnum.associated` in favour of `SomeEnum.membersof`
 - Refactored `@simd` implementation.
+- Improve error message for `Foo{}` when `Foo` is not a generic type #2574.
 
 ### Fixes
 - `Foo.is_eq` would return false if the type was a `typedef` and had an overload, but the underlying type was not comparable.

src/compiler/parse_expr.c

@@ -75,13 +75,8 @@ bool parse_range(ParseContext *c, Range *range)
 }
 bool parse_generic_expr_list(ParseContext *c, Expr ***exprs_ref)
 {
-	SourceSpan start = c->span;
 	advance_and_verify(c, TOKEN_LBRACE);
-	if (try_consume(c, TOKEN_RBRACE))
-	{
-		print_error_at(extend_span_with_token(start, c->prev_span), "At least one generic parameter was expected here.");
-		return false;
-	}
+	if (try_consume(c, TOKEN_RBRACE)) return true;
 	do
 	{
 		ASSIGN_EXPR_OR_RET(Expr *expr, parse_expr(c), false);
@@ -2064,7 +2059,7 @@ ADVANCE:;
 /**
  * string_literal ::= STRING+
  */
-static Expr *parse_string_literal(ParseContext *c, Expr *left, SourceSpan lhs_start)
+static Expr *parse_string_literal(ParseContext *c, Expr *left, SourceSpan lhs_start UNUSED)
 {
 	ASSERT(!left && "Had left hand side");
 	Expr *expr_string = EXPR_NEW_TOKEN(EXPR_CONST);
@@ -2082,7 +2077,7 @@ static Expr *parse_string_literal(ParseContext *c, Expr *left, SourceSpan lhs_st
 /*
  * bool ::= 'true' | 'false'
  */
-static Expr *parse_bool(ParseContext *c, Expr *left, SourceSpan lhs_start)
+static Expr *parse_bool(ParseContext *c, Expr *left, SourceSpan lhs_start UNUSED)
 {
 	ASSERT(!left && "Had left hand side");
 	Expr *number = EXPR_NEW_TOKEN(EXPR_CONST);

src/compiler/sema_decls.c

@@ -5262,13 +5262,22 @@ Decl *sema_analyse_parameterized_identifier(SemaContext *c, Path *decl_path, con
 
 	unsigned parameter_count = vec_size(module->parameters);
 	ASSERT(parameter_count > 0);
-	if (parameter_count != vec_size(params))
+	unsigned count = vec_size(params);
+	if (parameter_count != count)
 	{
-		ASSERT_AT(span, vec_size(params));
-		sema_error_at(c, extend_span_with_token(params[0]->span, vectail(params)->span),
-					  "The generic module expected %d arguments, but you supplied %d, did you make a mistake?",
-					  parameter_count,
-					  vec_size(params));
+		if (!count)
+		{
+			sema_error_at(c, invocation_span,
+						  "'%s' must be instantiatied with generic module arguments inside the '{}', did you forget them?", name, (int)parameter_count);
+
+		}
+		else
+		{
+			sema_error_at(c, extend_span_with_token(params[0]->span, vectail(params)->span),
+						  "The generic module expected %d argument(s), but you supplied %d, did you make a mistake?",
+						  parameter_count,
+						  vec_size(params));
+		}
 		return poisoned_decl;
 	}
 	if (!sema_generate_parameterized_name_to_scratch(c, module, params, true, was_recursive_ref)) return poisoned_decl;

test/test_suite/generic/generic_no_arg.c3

@@ -0,0 +1,30 @@
+module foo;
+import std, bar;
+struct Foo
+{
+	int i;
+}
+fn void foo(Foo f) {}
+
+fn void a()
+{
+	List{} a; // #error: must be instantiatied with generic module arguments
+}
+fn void b()
+{
+	foo(Foo{}); // #error: 'Foo' is not a generic type
+}
+fn void c()
+{
+	bar::test{}(); // #error: must be instantiatied with generic module arguments
+}
+
+fn int main()
+{
+
+	return 0;
+}
+
+module bar{Type};
+fn void test()
+{}

test/test_suite/generic/generic_no_params.c3

@@ -17,12 +17,12 @@ import std::collections::list;
 
 fn void test1()
 {
-	int x = values::test{}(); // #error: At least one generic parameter
+	int x = values::test{}(); // #error: must be instantiatied with generic
 }
 
 fn void test2()
 {
-	List{Values{ }} v1s; // #error: At least one generic parameter
+	List{Values{ }} v1s; // #error: must be instantiatied with generic
 }
 
 fn void main()