gc: echo literal in error message

Fixes #1192.

R=ken2
CC=golang-dev
https://golang.org/cl/4794062

src/cmd/gc/go.h

@@ -698,6 +698,7 @@ EXTERN	int	nsyntaxerrors;
 EXTERN	int	safemode;
 EXTERN	char	namebuf[NSYMB];
 EXTERN	char	lexbuf[NSYMB];
+EXTERN	char	litbuf[NSYMB];
 EXTERN	char	debug[256];
 EXTERN	Sym*	hash[NHASH];
 EXTERN	Sym*	importmyname;	// my name for package

src/cmd/gc/lex.c

@@ -728,6 +728,7 @@ l0:
 		yylval.val.u.sval = (Strlit*)cp;
 		yylval.val.ctype = CTSTR;
 		DBG("lex: string literal\n");
+		strcpy(litbuf, "string literal");
 		return LLITERAL;
 
 	case '\'':
@@ -744,6 +745,7 @@ l0:
 		mpmovecfix(yylval.val.u.xval, v);
 		yylval.val.ctype = CTINT;
 		DBG("lex: codepoint literal\n");
+		strcpy(litbuf, "string literal");
 		return LLITERAL;
 
 	case '/':
@@ -1133,6 +1135,8 @@ ncu:
 	}
 	yylval.val.ctype = CTINT;
 	DBG("lex: integer literal\n");
+	strcpy(litbuf, "literal ");
+	strcat(litbuf, lexbuf);
 	return LLITERAL;
 
 casedot:
@@ -1205,6 +1209,8 @@ casei:
 	}
 	yylval.val.ctype = CTCPLX;
 	DBG("lex: imaginary literal\n");
+	strcpy(litbuf, "literal ");
+	strcat(litbuf, lexbuf);
 	return LLITERAL;
 
 caseout:
@@ -1219,6 +1225,8 @@ caseout:
 	}
 	yylval.val.ctype = CTFLT;
 	DBG("lex: floating literal\n");
+	strcpy(litbuf, "literal ");
+	strcat(litbuf, lexbuf);
 	return LLITERAL;
 }
 
@@ -1859,6 +1867,12 @@ yytinit(void)
 	for(i=0; yytname[i] != nil; i++) {
 		s = yytname[i];
 		
+		if(strcmp(s, "LLITERAL") == 0) {
+			strcpy(litbuf, "literal");
+			yytname[i] = litbuf;
+			goto loop;
+		}
+		
 		// apply yytfix if possible
 		for(j=0; j<nelem(yytfix); j++) {
 			if(strcmp(s, yytfix[j].have) == 0) {

test/fixedbugs/bug349.go

+// errchk $G $D/$F.go
+
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// issue 1192 - detail in error
+
+package main
+
+func foo() (a, b, c int) {
+	return 0, 1 2.01  // ERROR "unexpected literal 2.01"
+}