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cmd/vet: check shift calculations with "unsafe" package

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vet should properly handle shift calculations via "unsafe"
package after the CL 37950.

Change-Id: I7737f2e656a5166337a17b92db46a0997f2a4e0e
Reviewed-on: https://go-review.googlesource.com/38064
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Aliaksandr Valialkin 2017-03-13 18:29:46 +02:00 committed by Josh Bleecher Snyder
parent cc71aa9ac4
commit 53937aad99
2 changed files with 4 additions and 23 deletions
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22
src/cmd/vet/shift.go
View file

@ -48,28 +48,6 @@ func checkLongShift(f *File, node ast.Node, x, y ast.Expr) {
return
}
// Ignore shifts where the shift amount is calculated using unsafe.
// These are used for bit-twiddling tricks.
var hasUnsafe bool
ast.Inspect(y, func(n ast.Node) bool {
sel, ok := n.(*ast.SelectorExpr)
if !ok {
return true
}
pkg, ok := sel.X.(*ast.Ident)
if !ok {
return true
}
if pkg.Name == "unsafe" {
hasUnsafe = true
return false
}
return true
})
if hasUnsafe {
return
}
v := f.pkg.types[y].Value
if v == nil {
return

5
src/cmd/vet/testdata/shift.go vendored
View file

@ -102,5 +102,8 @@ func ShiftTest() {
const oneIf64Bit = ^uint(0) >> 63 // allow large shifts of constants; they are used for 32/64 bit compatibility tricks
var h uintptr
h = h<<8 | (h >> (8 * (unsafe.Sizeof(h) - 1))) // shifts by unsafe amounts are safe
h = h<<8 | (h >> (8 * (unsafe.Sizeof(h) - 1)))
h <<= 8 * unsafe.Sizeof(h) // ERROR "too small for shift"
h >>= 7 * unsafe.Alignof(h)
h >>= 8 * unsafe.Alignof(h) // ERROR "too small for shift"
}