gc: distinguish fatal compiler bug from error+exit

R=ken2
CC=golang-dev
https://golang.org/cl/902044

src/cmd/gc/lex.c

@@ -110,8 +110,10 @@ main(int argc, char *argv[])
 
 		curio.infile = infile;
 		curio.bin = Bopen(infile, OREAD);
-		if(curio.bin == nil)
-			fatal("open %s: %r", infile);
+		if(curio.bin == nil) {
+			print("open %s: %r\n", infile);
+			errorexit();
+		}
 		curio.peekc = 0;
 		curio.peekc1 = 0;
 		curio.nlsemi = 0;
@@ -300,8 +302,10 @@ importfile(Val *f, int line)
 		return;
 	}
 
-	if(strlen(f->u.sval->s) != f->u.sval->len)
-		fatal("import path contains NUL");
+	if(strlen(f->u.sval->s) != f->u.sval->len) {
+		yyerror("import path contains NUL");
+		errorexit();
+	}
 
 	if(strcmp(f->u.sval->s, "unsafe") == 0) {
 		importpkg = mkpkg(f->u.sval);
@@ -317,20 +321,25 @@ importfile(Val *f, int line)
 		path = strlit(cleanbuf);
 	}
 
-	if(!findpkg(path))
-		fatal("can't find import: %Z", f->u.sval);
-
+	if(!findpkg(path)) {
+		yyerror("can't find import: %Z", f->u.sval);
+		errorexit();
+	}
 	importpkg = mkpkg(path);
 
 	imp = Bopen(namebuf, OREAD);
-	if(imp == nil)
-		fatal("can't open import: %Z", f->u.sval);
+	if(imp == nil) {
+		yyerror("can't open import: %Z", f->u.sval);
+		errorexit();
+	}
 	file = strdup(namebuf);
 
 	len = strlen(namebuf);
 	if(len > 2 && namebuf[len-2] == '.' && namebuf[len-1] == 'a') {
-		if(!skiptopkgdef(imp))
-			fatal("import not package file: %s", namebuf);
+		if(!skiptopkgdef(imp)) {
+			yyerror("import not package file: %s", namebuf);
+			errorexit();
+		}
 	}
 
 	// assume files move (get installed)

src/cmd/gc/obj.c

@@ -12,8 +12,11 @@ void
 dumpobj(void)
 {
 	bout = Bopen(outfile, OWRITE);
-	if(bout == nil)
-		fatal("cant open %s", outfile);
+	if(bout == nil) {
+		flusherrors();
+		print("can't create %s: %r\n", outfile);
+		errorexit();
+	}
 
 	Bprint(bout, "%s\n", thestring);
 	Bprint(bout, "  exports automatically generated from\n");

src/cmd/gc/subr.c

@@ -118,8 +118,11 @@ yyerrorl(int line, char *fmt, ...)
 
 	hcrash();
 	nerrors++;
-	if(nerrors >= 10 && !debug['e'])
-		fatal("too many errors");
+	if(nerrors >= 10 && !debug['e']) {
+		flusherrors();
+		print("%L: too many errors\n", line);
+		errorexit();
+	}
 }
 
 extern int yystate, yychar;
@@ -172,8 +175,11 @@ yyerror(char *fmt, ...)
 
 	hcrash();
 	nerrors++;
-	if(nerrors >= 10 && !debug['e'])
-		fatal("too many errors");
+	if(nerrors >= 10 && !debug['e']) {
+		flusherrors();
+		print("%L: too many errors\n", parserline());
+		errorexit();
+	}
 }
 
 void
@@ -195,12 +201,18 @@ fatal(char *fmt, ...)
 
 	flusherrors();
 
-	print("%L: fatal error: ", lineno);
+	print("%L: internal compiler error: ", lineno);
 	va_start(arg, fmt);
 	vfprint(1, fmt, arg);
 	va_end(arg);
 	print("\n");
 	
+	// If this is a released compiler version, ask for a bug report.
+	if(strncmp(getgoversion(), "release", 7) == 0) {
+		print("\n");
+		print("Please file a bug report including a short program that triggers the error.\n");
+		print("http://code.google.com/p/go/issues/entry?template=compilerbug");
+	}
 	hcrash();
 	errorexit();
 }
@@ -3549,8 +3561,10 @@ mkpkg(Strlit *path)
 	Pkg *p;
 	int h;
 	
-	if(strlen(path->s) != path->len)
-		fatal("import path contains NUL byte");
+	if(strlen(path->s) != path->len) {
+		yyerror("import path contains NUL byte");
+		errorexit();
+	}
 	
 	h = stringhash(path->s) & (nelem(phash)-1);
 	for(p=phash[h]; p; p=p->link)

src/cmd/gc/typecheck.c

@@ -1709,7 +1709,7 @@ exportassignok(Type *t, char *desc)
 					prefix = " in ";
 				else
 					desc = "";
-				yyerror("implicit assignment of %T field '%s'%s%s", t, s->name, prefix, desc);
+				yyerror("implicit assignment of unexported field '%s' of %T%s%s", s->name, t, prefix, desc);
 				goto no;
 			}
 			if(!exportassignok(f->type, desc))
@@ -1935,7 +1935,7 @@ typecheckcomplit(Node **np)
 				}
 				s = f->sym;
 				if(s != nil && !exportname(s->name) && s->pkg != localpkg)
-					yyerror("implicit assignment of %T field '%s' in struct literal", t, s->name);
+					yyerror("implicit assignment of unexported field '%s' in %T literal", s->name, t);
 				ll->n = typecheckconv(nil, ll->n, f->type, 0, "field value");
 				ll->n = nod(OKEY, newname(f->sym), ll->n);
 				ll->n->left->typecheck = 1;