Fix issue where rethrow in a macro not allowing optional caused an assert to trigger. #849

releasenotes.md

@@ -152,6 +152,7 @@
 - Updates to how variadics are implemented.
 - Fixes to shift checks.
 - Fixes to string parsing.
+- Bug when rethrowing an optional from a macro which didn't return an optional.
 - Fixed issues with ranged cases.
 - Disallow trailing ',' in function parameter list.
 - Fixed errors on flexible array slices.

src/compiler/sema_expr.c

@@ -6207,6 +6207,12 @@ static inline bool sema_expr_analyse_rethrow(SemaContext *context, Expr *expr)
 
 	if (context->active_scope.flags & (SCOPE_EXPR_BLOCK | SCOPE_MACRO))
 	{
+		TypeInfoId rtype = context->active_scope.flags & SCOPE_MACRO ? context->current_macro->func_decl.signature.rtype : 0;
+		if (rtype && !type_is_optional(typeinfotype(rtype)))
+		{
+			RETURN_SEMA_ERROR(expr, "Rethrow is only allowed in macros with an optional or inferred return type. "
+									"Did you mean to use '!!' instead?");
+		}
 		vec_add(context->returns, NULL);
 		expr->rethrow_expr.in_block = context->block_exit_ref;
 		expr->rethrow_expr.cleanup = context_get_defers(context, context->active_scope.defer_last, context->block_return_defer, false);

src/version.h

@@ -1 +1 @@
-#define COMPILER_VERSION "0.4.562"
+#define COMPILER_VERSION "0.4.563"

test/test_suite/errors/rethrow_macro.c3

@@ -0,0 +1,14 @@
+module testing;
+import std::io;
+
+macro char[] read(src, allocator, n)
+{
+    char* data = allocator.alloc(n)!; // #error: Rethrow is only allowed in macros
+    src.read_all(data[:n])!;
+}
+
+fn void main()
+{
+    ByteReader br;
+    read(br.as_stream(), mem::temp(), 10);
+}