From: Russ Cox <rsc@golang.org>
Date: Tue, 19 Jan 2010 00:00:13 +0000 (-0800)
Subject: gc: be more specific about copy type errors
X-Git-Tag: weekly.2010-01-27~84
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=07fc1457441110648abf4f01eced1741d509154e;p=gostls13.git

gc: be more specific about copy type errors

Fixes #539.

R=ken2
CC=golang-dev
https://golang.org/cl/190043
---

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index c63480faa2..0c18097dac 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -810,12 +810,19 @@ reswitch:
 			goto error;
 		toslice(&n->left);
 		toslice(&n->right);
+		defaultlit(&n->left, T);
+		defaultlit(&n->right, T);
 		if(!isslice(n->left->type) || !isslice(n->right->type)) {
-			yyerror("arguments to copy must be slices or array pointers");
+			if(!isslice(n->left->type) && !isslice(n->right->type))
+				yyerror("arguments to copy must be array pointer or slice; have %lT, %lT", n->left->type, n->right->type);
+			else if(!isslice(n->left->type))
+				yyerror("first argument to copy should be array pointer or slice; have %lT", n->left->type);
+			else
+				yyerror("second argument to copy should be array pointer or slice; have %lT", n->right->type);
 			goto error;
 		}
 		if(!eqtype(n->left->type, n->right->type)) {
-			yyerror("arguments to copy must have the same type element type");
+			yyerror("arguments to copy have different element types %lT and %lT", n->left->type, n->right->type);
 			goto error;
 		}
 		goto ret;