ww source: align UTF-8 BOM placement

test/wcc/100_lex.c

@@ -61,6 +61,7 @@ struct row { const char *src, *expect; };
 
 static const struct row rows[] = {
 	{ "",                "" },
+	{ "\xef\xbb\xbf" "package main;", "package IDENT(main) ;" },
 	{ "  \t\n  ",        "" },
 	{ "// comment\n",    "" },
 	{ "/* a /b/ c */",   "" },
@@ -172,7 +173,29 @@ runrewind(void)
 	return ok;
 }
 
+static int
+runbompos(void)
+{
+	const char *src = "\xef\xbb\xbf" "package main;";
+	Arena *a = newarena();
+	Lex l;
+	lexinit(&l, a, "<test>", src, strlen(src));
+	Tok t = lexnext(&l);
+	int ok = t.kind == TK_MODULE && t.pos.line == 1 && t.pos.col == 4;
+	if (!ok)
+		fprintf(stderr, "leading BOM position: want 1:4 got %d:%d\n",
+		    t.pos.line, t.pos.col);
+	freearena(a);
+	return ok;
+}
+
 static const char *const errrows[] = {
+	"\xef\xbb\xbf" "\xef\xbb\xbf" "package main;",
+	"package \xef\xbb\xbf" "main;",
+	"// \xef\xbb\xbf\n",
+	"/* \xef\xbb\xbf */",
+	"\"\xef\xbb\xbf\"",
+	"'\xef\xbb\xbf'",
 	"'\\uZ'",		/* unexpected rune scanning for escape */
 	"\"\\u00g0\"",		/* non-hex digit inside a string escape */
 	"'\\u00",		/* unexpected EOF scanning for escape */
@@ -194,6 +217,8 @@ main(void)
 	}
 	if (!runrewind())
 		fail++;
+	if (!runbompos())
+		fail++;
 	for (size_t i = 0; i < sizeof errrows / sizeof errrows[0]; i++) {
 		if (!runerr(errrows[i])) {
 			fprintf(stderr, "errrow %zu failed\n", i);