This source file is part of the SubC compiler, which is described in the book

Practical Compiler Construction.

You might prefer to download the compiler source code. It is in the public domain.

Error Handling

Error reporting and parser re-synchronization is done in this module.

 *	NMH's Simple C Compiler, 2011,2012
 *	Error handling

#include "defs.h"
#include "data.h"
#include "decl.h"

static void cleanup(void) {
	if (!O_testonly && NULL != Basefile) {
		remove(newfilename(Basefile, 's'));
		remove(newfilename(Basefile, 'o'));

void error(char *s, char *a) {
	if (Syntoken) return;
	if (!Errors) cleanup();
	fprintf(stderr, "error: %s: %d: ", File, Line);
	fprintf(stderr, s, a);
	fprintf(stderr, "\n");
	if (++Errors > 10) {
		Errors = 0;
		fatal("too many errors");

void fatal(char *s) {
	error(s, NULL);
	error("fatal error, stop", NULL);

void cerror(char *s, int c) {
	char	buf[32];

	if (isprint(c))
		sprintf(buf, "'%c' (\\x%x)", c, c);
		sprintf(buf, "\\x%x", c);
	error(s, buf);

int synch(int syn) {
	int	t;

	t = scan();
	while (t != syn) {
		if (EOF == t)
			fatal("found EOF in error recovery");
		t = next();
	Syntoken = syn;
	return t;

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