Prevent #hash arguments from taking code that modifies ct variables. #1794

releasenotes.md

@@ -30,7 +30,7 @@
 - Allowed passing arguments to @test / @benchmark runners via `c3c test[benchmark] -- -o --opt1 <arg1>`
 - Handle bytes and string literals the same way in terms of zero termination.
 - Function comments are stored and displayed with -P.
-
+- Prevent `#hash` arguments from taking code that modifies ct variables. #1794
 ### Fixes
 - Fix case trying to initialize a `char[*]*` from a String.
 - Fix Map & HashMap `put_all_for_create` not copying all elements, causing `init_from_map` to create incomplete copy.

src/compiler/compiler_internal.h

@@ -1679,6 +1679,7 @@ typedef struct
 	bool ensures : 1;
 	bool pure : 1;
 	bool in_no_eval : 1;
+	bool in_other : 1;
 	SourceSpan in_if_resolution;
 	Decl **opt_returns;
 	union

src/compiler/sema_expr.c

@@ -5677,6 +5677,11 @@ static bool sema_expr_analyse_ct_identifier_assign(SemaContext *context, Expr *e
 	// Evaluate right side to using inference from last type.
 	if (!sema_analyse_inferred_expr(context, left->type, right)) return false;
 
+	if (context->call_env.in_other)
+	{
+		RETURN_SEMA_ERROR(left, "Compile time variables may only be modified in the scope they are defined in.");
+	}
+
 	left->ct_ident_expr.decl->var.init_expr = right;
 	expr_replace(expr, right);
 	left->ct_ident_expr.decl->type = right->type;
@@ -5696,6 +5701,12 @@ static bool sema_expr_analyse_ct_type_identifier_assign(SemaContext *context, Ex
 
 	Decl *decl = sema_find_symbol(context, info->unresolved.name);
 	if (!decl) RETURN_SEMA_ERROR(info, "'%s' is not defined in this scope yet.", info->unresolved.name);
+
+	if (context->call_env.in_other)
+	{
+		RETURN_SEMA_ERROR(left, "Compile time variables may only be modified in the scope they are defined in.");
+	}
+
 	decl->var.init_expr = right;
 	expr->expr_kind = EXPR_NOP;
 	expr->type = type_void;
@@ -5792,6 +5803,10 @@ static bool sema_binary_analyse_ct_common_assign(SemaContext *context, Expr *exp
 	Decl *left_var = left->ct_ident_expr.decl;
 	if (!sema_cast_ct_ident_rvalue(context, left)) return false;
 
+	if (context->call_env.in_other)
+	{
+		RETURN_SEMA_ERROR(left, "Compile time variables may only be modified in the scope they are defined in.");
+	}
 	expr->binary_expr.operator = binaryop_assign_base_op(expr->binary_expr.operator);
 
 	if (!sema_expr_analyse_binary(context, expr, NULL)) return false;
@@ -9526,7 +9541,13 @@ static inline bool sema_analyse_expr_dispatch(SemaContext *context, Expr *expr,
 			if (expr->resolve_status == RESOLVE_DONE) return expr_ok(expr);
 			ASSERT_SPAN(expr, expr->resolve_status == RESOLVE_NOT_DONE);
 			expr->resolve_status = RESOLVE_RUNNING;
-			return sema_analyse_expr_dispatch(context, expr, check);
+			{
+				bool in_other = context->call_env.in_other;
+				context->call_env.in_other = true;
+				bool success = sema_analyse_expr_dispatch(context, expr, check);
+				context->call_env.in_other = in_other;
+				return success;
+			}
 		case EXPR_CT_CASTABLE:
 			return sema_expr_analyse_castable(context, expr);
 		case EXPR_EMBED:

test/test_suite/compile_time/mod_in_other_scope.c3

@@ -0,0 +1,23 @@
+module test;
+
+macro void @foo(#a)
+{
+	#a;
+}
+
+macro void @bar(#a)
+{
+	$typeof(#a) x;
+}
+fn int main()
+{
+	int $i;
+	var $Type;
+	@foo($Type = int); // #error: only be modified
+	@foo($i = 2); // #error: only be modified
+	@foo($i += 1); // #error: only be modified
+	@bar($Type = int); // #error: only be modified
+	@bar($i = 2); // #error: only be modified
+	@bar($i += 1); // #error: only be modified
+	return 0;
+}

test/test_suite/macros/hash_ident.c3

@@ -18,8 +18,8 @@ fn void main()
     int x = 0;
     @cofefe(x += 1);
     @cofefe(xx());
-    @cofefe($x += 1);
-    $assert $x == 2;
+    $typeof($x += 1) xx;
+    $assert $x == 1;
     @cofefe(y += 1); // #error: 'y' could not be found
 }