cmd/internal/gc: unsafe.Pointer constants may only be converted to uintptr
Fixes #8927.
Change-Id: I638cddd439dd2d4eeef5474118cfcbde0c8a5a43
Reviewed-on: https://go-review.googlesource.com/9632
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/cmd/internal/gc/const.go b/src/cmd/internal/gc/const.go
index ad29158..5ec54bd 100644
--- a/src/cmd/internal/gc/const.go
+++ b/src/cmd/internal/gc/const.go
@@ -204,6 +204,9 @@
}
case CTINT, CTRUNE, CTFLT, CTCPLX:
+ if n.Type.Etype == TUNSAFEPTR && t.Etype != TUINTPTR {
+ goto bad
+ }
ct := int(n.Val.Ctype)
if Isint[et] {
switch ct {
@@ -264,8 +267,6 @@
defaultlit(&n, nil)
*np = n
}
-
- return
}
func copyval(v Val) Val {
@@ -396,6 +397,11 @@
return
}
+ // Only uintptrs may be converted to unsafe.Pointer, which cannot overflow.
+ if t.Etype == TUNSAFEPTR {
+ return
+ }
+
if !doesoverflow(v, t) {
return
}
diff --git a/test/convlit.go b/test/convlit.go
index 8a6145d..904e1e6 100644
--- a/test/convlit.go
+++ b/test/convlit.go
@@ -9,6 +9,8 @@
package main
+import "unsafe"
+
// explicit conversion of constants
var x1 = string(1)
var x2 string = string(1)
@@ -18,6 +20,11 @@
var x6 = int(1e100) // ERROR "overflow"
var x7 = float32(1e1000) // ERROR "overflow"
+// unsafe.Pointer can only convert to/from uintptr
+var _ = string(unsafe.Pointer(uintptr(65))) // ERROR "convert"
+var _ = float64(unsafe.Pointer(uintptr(65))) // ERROR "convert"
+var _ = int(unsafe.Pointer(uintptr(65))) // ERROR "convert"
+
// implicit conversions merit scrutiny
var s string
var bad1 string = 1 // ERROR "conver|incompatible|invalid|cannot"
