cmd/gc: clean up string index errors

Unify with array/slice errors, which were already good.

Fixes #4232.

R=ken2
CC=golang-dev
https://golang.org/cl/7271046

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 1bfa0cc471818fbdd16ee20f580740ddb94fd7a5..d029b8bc6c66f5ddc70b1ad8c5e4f27b843530f2 100644 (file)
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -832,23 +832,34 @@ reswitch:
                        yyerror("invalid operation: %N (index of type %T)", n, t);
                        goto error;
 
+
+               case TSTRING:
                case TARRAY:
                        defaultlit(&n->right, T);
-                       n->type = t->type;
+                       if(t->etype == TSTRING)
+                               n->type = types[TUINT8];
+                       else
+                               n->type = t->type;
+                       why = "string";
+                       if(t->etype == TARRAY) {
+                               if(isfixedarray(t))
+                                       why = "array";
+                               else
+                                       why = "slice";
+                       }
                        if(n->right->type != T && !isint[n->right->type->etype]) {
-                               yyerror("non-integer array index %N", n->right);
+                               yyerror("non-integer %s index %N", why, n->right);
                                break;
                        }
                        if(n->right->op == OLITERAL) {
-                               if(mpgetfix(n->right->val.u.xval) < 0) {
-                                       why = isfixedarray(t) ? "array" : "slice";
+                               if(mpgetfix(n->right->val.u.xval) < 0)
                                        yyerror("invalid %s index %N (index must be non-negative)", why, n->right);
-                               } else if(isfixedarray(t) && t->bound > 0 && mpgetfix(n->right->val.u.xval) >= t->bound)
+                               else if(isfixedarray(t) && t->bound > 0 && mpgetfix(n->right->val.u.xval) >= t->bound)
                                        yyerror("invalid array index %N (out of bounds for %d-element array)", n->right, t->bound);
-                               else if(mpcmpfixfix(n->right->val.u.xval, maxintval[TINT]) > 0) {
-                                       why = isfixedarray(t) ? "array" : "slice";
+                               else if(isconst(n->left, CTSTR) && mpgetfix(n->right->val.u.xval) >= n->left->val.u.sval->len)
+                                       yyerror("invalid string index %N (out of bounds for %d-byte string)", n->right, n->left->val.u.sval->len);
+                               else if(mpcmpfixfix(n->right->val.u.xval, maxintval[TINT]) > 0)
                                        yyerror("invalid %s index %N (index too large)", why, n->right);
-                               }
                        }
                        break;
 
@@ -860,13 +871,6 @@ reswitch:
                        n->type = t->type;
                        n->op = OINDEXMAP;
                        break;
-
-               case TSTRING:
-                       defaultlit(&n->right, types[TUINT]);
-                       if(n->right->type != T && !isint[n->right->type->etype])
-                               yyerror("non-integer string index %N", n->right);
-                       n->type = types[TUINT8];
-                       break;
                }
                goto ret;
 

diff --git a/test/fixedbugs/bug205.go b/test/fixedbugs/bug205.go
index de17cb698416c1988dc53682f9c421086b85862b..769837d04ee4c894d4750fb7529ed355ee6b1c7c 100644 (file)
--- a/test/fixedbugs/bug205.go
+++ b/test/fixedbugs/bug205.go
@@ -11,8 +11,8 @@ var s string;
 var m map[string]int;
 
 func main() {
-       println(t["hi"]);       // ERROR "integer"
-       println(s["hi"]);       // ERROR "integer" "to type uint"
-       println(m[0]);  // ERROR "map index"
+       println(t["hi"]);       // ERROR "non-integer slice index"
+       println(s["hi"]);       // ERROR "non-integer string index"
+       println(m[0]);  // ERROR "as type string in map index"
 }
 

diff --git a/test/fixedbugs/issue4232.go b/test/fixedbugs/issue4232.go
new file mode 100644 (file)
index 0000000..29ddfa8
--- /dev/null
+++ b/test/fixedbugs/issue4232.go
@@ -0,0 +1,33 @@
+// errorcheck
+
+// Copyright 2013 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.
+
+package p
+
+func f() {
+       var a [10]int
+       _ = a[-1] // ERROR "invalid array index -1"
+       _ = a[-1:] // ERROR "invalid slice index -1"
+       _ = a[:-1] // ERROR "invalid slice index -1"
+       _ = a[10] // ERROR "invalid array index 10"
+
+       var s []int
+       _ = s[-1] // ERROR "invalid slice index -1"
+       _ = s[-1:] // ERROR "invalid slice index -1"
+       _ = s[:-1] // ERROR "invalid slice index -1"
+       _ = s[10]
+
+       const c = "foo"
+       _ = c[-1] // ERROR "invalid string index -1"
+       _ = c[-1:] // ERROR "invalid slice index -1"
+       _ = c[:-1] // ERROR "invalid slice index -1"
+       _ = c[3] // ERROR "invalid string index 3"
+
+       var t string
+       _ = t[-1] // ERROR "invalid string index -1"
+       _ = t[-1:] // ERROR "invalid slice index -1"
+       _ = t[:-1] // ERROR "invalid slice index -1"
+       _ = t[3]
+}