gc: small fixes to fmt.c

don't crash when printing error messages about symbols in a garbled state.
render OCOMPLIT in export mode.

R=rsc
CC=golang-dev
https://golang.org/cl/5466045

diff --git a/src/cmd/gc/fmt.c b/src/cmd/gc/fmt.c
index 9733095019d78ac218856380e18f87f4572cb457..7c50b51e449ca12195cee87dfca0fb497529d80e 100644 (file)
--- a/src/cmd/gc/fmt.c
+++ b/src/cmd/gc/fmt.c
@@ -511,7 +511,8 @@ symfmt(Fmt *fp, Sym *s)
                                return fmtprint(fp, "%s.%s", s->pkg->name, s->name);    // dcommontype, typehash
                        return fmtprint(fp, "%s.%s", s->pkg->prefix, s->name);  // (methodsym), typesym, weaksym
                case FExp:
-                       return fmtprint(fp, "@\"%Z\".%s", s->pkg->path, s->name);
+                       if(s->pkg != builtinpkg)
+                               return fmtprint(fp, "@\"%Z\".%s", s->pkg->path, s->name);
                }
        }
 
@@ -1073,7 +1074,9 @@ exprfmt(Fmt *f, Node *n, int prec)
                return fmtprint(f, "%T", n->type);
 
        case OTARRAY:
-               return fmtprint(f, "[]%N", n->left);
+               if(n->left)
+                       return fmtprint(f, "[]%N", n->left);
+               return fmtprint(f, "[]%N", n->right);  // happens before typecheck
 
        case OTPAREN:
                return fmtprint(f, "(%N)", n->left);
@@ -1109,7 +1112,9 @@ exprfmt(Fmt *f, Node *n, int prec)
                return fmtprint(f, "%T { %H }", n->type, n->nbody);
 
        case OCOMPLIT:
-               return fmtstrcpy(f, "composite literal");
+               if(fmtmode == FErr)
+                       return fmtstrcpy(f, "composite literal");
+               return fmtprint(f, "%N{ %,H }", n->right, n->list);
 
        case OPTRLIT:
                return fmtprint(f, "&%N", n->left);
@@ -1401,7 +1406,7 @@ Sconv(Fmt *fp)
        if(s == S)
                return fmtstrcpy(fp, "<S>");
 
-       if(s->name[0] == '_' && s->name[1] == '\0')
+       if(s->name && s->name[0] == '_' && s->name[1] == '\0')
                return fmtstrcpy(fp, "_");
 
        sf = fp->flags;