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gc: shift type bug

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Fixes #1664.

R=ken2
CC=golang-dev
https://golang.org/cl/4798056
This commit is contained in:
Russ Cox 2011-07-28 13:03:30 -04:00
parent ca68b2810d
commit 4389192669
2 changed files with 39 additions and 2 deletions
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20
src/cmd/gc/const.c
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@ -947,8 +947,24 @@ defaultlit(Node **np, Type *t)
dump("defaultlit", n);
fatal("defaultlit");
}
defaultlit(&n->left, t);
defaultlit(&n->right, t);
// n is ideal, so left and right must both be ideal.
// n has not been computed as a constant value,
// so either left or right must not be constant.
// The only 'ideal' non-constant expressions are shifts. Ugh.
// If one of these is a shift and the other is not, use that type.
// When compiling x := 1<<i + 3.14, this means we try to push
// the float64 down into the 1<<i, producing the correct error
// (cannot shift float64).
if(t == T && (n->right->op == OLSH || n->right->op == ORSH)) {
defaultlit(&n->left, T);
defaultlit(&n->right, n->left->type);
} else if(t == T && (n->left->op == OLSH || n->left->op == ORSH)) {
defaultlit(&n->right, T);
defaultlit(&n->left, n->right->type);
} else {
defaultlit(&n->left, t);
defaultlit(&n->right, t);
}
if(n->type == idealbool || n->type == idealstring)
n->type = types[n->type->etype];
else

21
test/fixedbugs/bug363.go Normal file
View File

@ -0,0 +1,21 @@
// 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 1664
package main
func main() {
var i uint = 33
var a = (1<<i) + 4.5 // ERROR "shift of type float64"
println(a)
var b = (1<<i) + 4.0 // ERROR "shift of type float64"
println(b)
var c int64 = (1<<i) + 4.0 // ok - it's all int64
println(b)
}