Add --max-macro-iterations to set macro iteration limit.

releasenotes.md

@@ -9,6 +9,7 @@
 - `"build-dir"` option now available for `project.json`, added to project. #2323
 - Allow `..` ranges to use "a..a-1" in order to express zero length.
 - Disallow aliasing of `@local` symbols with a higher visibility in the alias.
+- Add `--max-macro-iterations` to set macro iteration limit.
 
 ### Fixes
 - Bug in `io::write_using_write_byte`.

src/build/build.h

@@ -586,6 +586,7 @@ typedef struct BuildOptions_
 	SanitizeMode sanitize_mode;
 	uint32_t max_vector_size;
 	uint32_t max_stack_object_size;
+	uint32_t max_macro_iterations;
 	bool print_keywords;
 	bool print_attributes;
 	bool print_builtins;
@@ -728,6 +729,7 @@ typedef struct
 	uint32_t symtab_size;
 	uint32_t max_vector_size;
 	uint32_t max_stack_object_size;
+	uint32_t max_macro_iterations;
 	uint32_t switchrange_max_size;
 	uint32_t switchjump_max_size;
 	const char **args;

src/build/build_options.c

@@ -182,6 +182,7 @@ static void usage(bool full)
 		print_opt("--win-debug=<option>", "Select debug output on Windows: codeview or dwarf (default: codeview).");
 		print_opt("--max-vector-size <number>", "Set the maximum vector bit size to allow (default: 4096).");
 		print_opt("--max-stack-object-size <number>", "Set the maximum size of a stack object in KB (default: 128).");
+		print_opt("--max-macro-iterations <number>", "Set the maximum number of iterations in a macro loop (default: 1048575).");
 		PRINTF("");
 		print_opt("--print-linking", "Print linker arguments.");
 		PRINTF("");
@@ -972,10 +973,18 @@ static void parse_option(BuildOptions *options)
 			{
 				int size = (at_end() || next_is_opt()) ? 0 : atoi(next_arg());
 				if (size < 1) error_exit("Expected a valid positive integer >= 1 for --max-stack-object-size.");
-				if (size > MAX_STACK_OBJECT_SIZE) error_exit("Expected a valid positive integer <= %u for --max-vector-size.", (unsigned)MAX_STACK_OBJECT_SIZE);
+				if (size > MAX_STACK_OBJECT_SIZE) error_exit("Expected a valid positive integer <= %u for --max-stack-object-size.", (unsigned)MAX_STACK_OBJECT_SIZE);
 				options->max_stack_object_size = size;
 				return;
 			}
+			if (match_longopt("max-macro-iterations"))
+			{
+				int size = (at_end() || next_is_opt()) ? 0 : atoi(next_arg());
+				if (size < 1) error_exit("Expected a valid positive integer >= 128 for --max-macro-iterations");
+				if (size > MAX_MACRO_ITERATIONS) error_exit("Expected a valid positive integer <= %u for --max-macro-iterations.", (unsigned)MAX_MACRO_ITERATIONS);
+				options->max_macro_iterations = size;
+				return;
+			}
 			if (match_longopt("max-vector-size"))
 			{
 				int size = (at_end() || next_is_opt()) ? 0 : atoi(next_arg());

src/build/builder.c

@@ -432,6 +432,7 @@ static void update_build_target_from_options(BuildTarget *target, BuildOptions *
 	OVERRIDE_IF_SET(symtab_size);
 	OVERRIDE_IF_SET(max_vector_size);
 	OVERRIDE_IF_SET(max_stack_object_size);
+	OVERRIDE_IF_SET(max_macro_iterations);
 	OVERRIDE_IF_SET(win.def);
 	OVERRIDE_IF_SET(no_entry);
 	OVERRIDE_IF_SET(echo_prefix);
@@ -448,7 +449,7 @@ static void update_build_target_from_options(BuildTarget *target, BuildOptions *
 
 	if (!target->max_vector_size) target->max_vector_size = DEFAULT_VECTOR_WIDTH;
 	if (!target->max_stack_object_size) target->max_stack_object_size = DEFAULT_STACK_OBJECT_SIZE;
-
+	if (!target->max_macro_iterations) target->max_macro_iterations = DEFAULT_MAX_MACRO_ITERATIONS;
 	if (target->quiet && !options->verbosity_level) options->verbosity_level = -1;
 
 	if (options->silence_deprecation || options->verbosity_level < 0) target->silence_deprecation = true;

src/compiler/compiler_internal.h

@@ -42,7 +42,6 @@ typedef uint16_t FileId;
 #define INITIAL_SYMBOL_MAP 0x10000
 #define INITIAL_GENERIC_SYMBOL_MAP 0x1000
 #define MAX_INCLUDE_DIRECTIVES 2048
-#define MAX_MACRO_ITERATIONS 0xFFFFFF
 #define MAX_PARAMS 255
 #define MAX_BITSTRUCT 0x1000
 #define MAX_MEMBERS ((StructIndex)1) << 15

src/compiler/sema_stmts.c

@@ -3110,8 +3110,13 @@ static inline bool sema_analyse_ct_for_stmt(SemaContext *context, Ast *statement
 	// We set a maximum of macro iterations.
 	// we might consider reducing this.
 	unsigned current_ct_scope = sema_context_push_ct_stack(context);
-	for (int i = 0; i < MAX_MACRO_ITERATIONS; i++)
+	for (int i = 0; ; i++)
 	{
+		if (i >= compiler.build.max_macro_iterations)
+		{
+			SEMA_ERROR(statement, "Too many iterations in '$for' (it exceeded %d), you can change this limit using '--max-macro-iterations'.", compiler.build.max_macro_iterations);
+			goto FAILED;
+		}
 		sema_context_pop_ct_stack(context, current_ct_scope);
 		// First evaluate the cond, which we note that we *must* have.
 		// we need to make a copy

src/utils/common.h

@@ -23,6 +23,8 @@
 #define NO_ARENA 0
 #define MAX_VECTOR_WIDTH 65536
 #define MAX_STACK_OBJECT_SIZE (256 * 1024)
+#define MAX_MACRO_ITERATIONS 0xFFFFFF
+#define DEFAULT_MAX_MACRO_ITERATIONS 0xFFFFF
 #define DEFAULT_VECTOR_WIDTH 4096
 #define DEFAULT_STACK_OBJECT_SIZE 64
 #define MAX_ARRAY_SIZE INT64_MAX

test/test_suite/compile_time/ct_for_limit.c3

@@ -0,0 +1,6 @@
+fn int main()
+{
+	$for var $i = 0; $i < 1000000000; $i++: // #error: Too many iterations in
+	$endfor
+	return 0;
+}