Crash when trying to define a method macro that isn't @construct but has no arguments.

releasenotes.md

@@ -15,6 +15,7 @@
 - Test runner with tracking allocator didn't properly handle teardown_fn
 - Correctly give an error if a character literal contains a line break.
 - Implicitly unwrapped optional value in defer incorrectly copied #1982.
+- Crash when trying to define a method macro that isn't `@construct` but has no arguments.
 
 ### Stdlib changes
 

src/compiler/sema_decls.c

@@ -11,7 +11,7 @@
 static inline bool sema_analyse_func_macro(SemaContext *context, Decl *decl, AttributeDomain domain, bool *erase_decl);
 static inline bool sema_analyse_func(SemaContext *context, Decl *decl, bool *erase_decl);
 static inline bool sema_analyse_macro(SemaContext *context, Decl *decl, bool *erase_decl);
-static inline bool sema_analyse_signature(SemaContext *context, Signature *sig, TypeInfo *method_parent, bool is_export, bool is_deprecated, SourceSpan span);
+static inline bool sema_analyse_signature(SemaContext *context, Signature *sig, TypeInfo *method_parent, bool is_export, bool is_deprecated, Decl *decl);
 static inline bool sema_analyse_main_function(SemaContext *context, Decl *decl);
 static inline bool sema_check_param_uniqueness_and_type(SemaContext *context, Decl **decls, Decl *current,
                                                         unsigned current_index, unsigned count);
@@ -1093,7 +1093,7 @@ ERROR:
 	return decl_poison(decl);
 }
 
-static inline bool sema_analyse_signature(SemaContext *context, Signature *sig, TypeInfo *method_parent, bool is_export, bool is_deprecated, SourceSpan span)
+static inline bool sema_analyse_signature(SemaContext *context, Signature *sig, TypeInfo *method_parent, bool is_export, bool is_deprecated, Decl *decl)
 {
 	Variadic variadic_type = sig->variadic;
 	Decl **params = sig->params;
@@ -1177,6 +1177,15 @@ static inline bool sema_analyse_signature(SemaContext *context, Signature *sig,
 		param->var.is_self = true;
 	}
 
+	// Ensure it has at least one parameter if method.
+	if (method_parent && !vec_size(params) && decl->operator != OVERLOAD_CONSTRUCT)
+	{
+		RETURN_SEMA_ERROR(decl, "A method must start with an argument of the type "
+								"it is a method of, e.g. 'fn void %s.%s(%s* self)', "
+								"unless it is a 'construct' method,",
+								type_to_error_string(method_parent->type), decl->name, type_to_error_string(method_parent->type));
+	}
+
 	// Check parameters
 	for (unsigned i = 0; i < param_count; i++)
 	{
@@ -1352,7 +1361,7 @@ bool sema_analyse_function_signature(SemaContext *context, Decl *func_decl, Type
 
 	bool deprecated = func_decl->resolved_attributes && func_decl->attrs_resolved && func_decl->attrs_resolved->deprecated;
 
-	if (!sema_analyse_signature(context, signature, parent, func_decl->is_export, deprecated, func_decl->span)) return false;
+	if (!sema_analyse_signature(context, signature, parent, func_decl->is_export, deprecated, func_decl)) return false;
 
 	Variadic variadic_type = signature->variadic;
 
@@ -2358,15 +2367,6 @@ static inline bool sema_analyse_method(SemaContext *context, Decl *decl)
 
 	bool is_constructor = decl->operator == OVERLOAD_CONSTRUCT;
 
-	// Ensure it has at least one parameter.
-	if (!vec_size(params) && !is_constructor)
-	{
-		RETURN_SEMA_ERROR(decl, "A method must start with an argument of the type "
-								"it is a method of, e.g. 'fn void %s.%s(%s* self)', "
-								"unless it is a 'construct' method,",
-		                  type_to_error_string(par_type), decl->name, type_to_error_string(par_type));
-	}
-
 	// Ensure that the first parameter is valid.
 	if (!is_constructor && !sema_is_valid_method_param(context, params[0], par_type, is_dynamic)) return false;
 
@@ -3874,7 +3874,7 @@ static inline bool sema_analyse_macro(SemaContext *context, Decl *decl, bool *er
 
 	if (!sema_analyse_signature(context, &decl->func_decl.signature,
 	                            type_infoptrzero(decl->func_decl.type_parent),
-	                            false, deprecated, decl->span)) return false;
+	                            false, deprecated, decl)) return false;
 
 	DeclId body_param = decl->func_decl.body_param;
 	if (!decl->func_decl.signature.is_at_macro && body_param && !decl->func_decl.signature.is_safemacro)

test/test_suite/macro_methods/macro_methods_no_args.c3

@@ -0,0 +1,17 @@
+import std::io;
+// Issue #1990
+struct Foo
+{
+	uint field;
+}
+
+macro Foo.bar() // #error: A method must start with an argument
+{
+	io.printn("UwU");
+}
+
+fn void main()
+{
+	Foo foo = {};
+	foo.bar();
+}