wcc: reject final-band integer overflow; restore rewind columns

test/wcc/100_lex.c

@@ -80,6 +80,7 @@ static const struct row rows[] = {
 	{ "0xDE_AD_BE_EF",   "INT(3735928559)" },
 	{ "0b1010",          "INT(10)" },
 	{ "0o777",           "INT(511)" },
+	{ "18446744073709551616", "ERR(18446744073709551616)" },
 	{ "3.14",            "FLOAT(3.14)" },
 	{ "1.5e3",           "FLOAT(1500)" },
 
@@ -149,6 +150,28 @@ runerr(const char *src)
 	return ok;
 }
 
+static int
+runrewind(void)
+{
+	const char *src = "1foo bar";
+	Arena *a = newarena();
+	Lex l;
+	lexinit(&l, a, "<test>", src, strlen(src));
+	Tok n = lexnext(&l);
+	Tok f = lexnext(&l);
+	Tok b = lexnext(&l);
+	int ok = n.kind == TK_INT && n.pos.col == 1 && n.v.uval == 1
+	    && f.kind == TK_IDENT && f.pos.col == 2
+	    && strcmp(f.text, "foo") == 0
+	    && b.kind == TK_IDENT && b.pos.col == 6
+	    && strcmp(b.text, "bar") == 0;
+	if (!ok)
+		fprintf(stderr, "suffix rewind columns: want 1,2,6 got %d,%d,%d\n",
+		    n.pos.col, f.pos.col, b.pos.col);
+	freearena(a);
+	return ok;
+}
+
 static const char *const errrows[] = {
 	"'\\uZ'",		/* unexpected rune scanning for escape */
 	"\"\\u00g0\"",		/* non-hex digit inside a string escape */
@@ -169,6 +192,8 @@ main(void)
 			fail++;
 		}
 	}
+	if (!runrewind())
+		fail++;
 	for (size_t i = 0; i < sizeof errrows / sizeof errrows[0]; i++) {
 		if (!runerr(errrows[i])) {
 			fprintf(stderr, "errrow %zu failed\n", i);

test/wcc/data/r989_intoverflow_dec_overflow/case.ww

@@ -1,7 +1,7 @@
 //ww:error "bad integer literal"
-// 989_intoverflow_reject dec_overflow: a 21-digit decimal exceeds u64.
+// Exact final-digit band: MAX/10 with 6 greater than MAX%10.
 package main;
 export fn main() i32 = {
-	let x: u64 = 99999999999999999999u64;
+	let x: u64 = 18446744073709551616u64;
 	return x: i32;
 };