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cmd/compile/internal/types2: use type variables consistently in Checker.conversion 

We have V and T and Vu and Tu. When calling the various isX predicates
consistently use Vu and Tu.

(We could also use V an T because the predicates call under anyway,
but using Vu and Tu removes an unnecessary call to Named.under if
V or T are *Named.)

Also, removed some outdated comments.

Change-Id: I6fcd9ce5f6292e89ac2afd597b72fd0790e84ff1
Reviewed-on: https://go-review.googlesource.com/c/go/+/362895
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-11-09 21:12:03 -08:00
parent 17980dff36
commit 0aa194f758
1 changed files with 8 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
src/cmd/compile/internal/types2/conversions.go
View File

@ -142,39 +142,39 @@ func (x *operand) convertibleTo(check *Checker, T Type, cause *string) bool {
}
// "V and T are both integer or floating point types"
if isIntegerOrFloat(V) && isIntegerOrFloat(T) {
if isIntegerOrFloat(Vu) && isIntegerOrFloat(Tu) {
return true
}
// "V and T are both complex types"
if isComplex(V) && isComplex(T) {
if isComplex(Vu) && isComplex(Tu) {
return true
}
// "V is an integer or a slice of bytes or runes and T is a string type"
if (isInteger(V) || isBytesOrRunes(Vu)) && isString(T) {
if (isInteger(Vu) || isBytesOrRunes(Vu)) && isString(Tu) {
return true
}
// "V is a string and T is a slice of bytes or runes"
if isString(V) && isBytesOrRunes(Tu) {
if isString(Vu) && isBytesOrRunes(Tu) {
return true
}
// package unsafe:
// "any pointer or value of underlying type uintptr can be converted into a unsafe.Pointer"
if (isPointer(Vu) || isUintptr(Vu)) && isUnsafePointer(T) {
if (isPointer(Vu) || isUintptr(Vu)) && isUnsafePointer(Tu) {
return true
}
// "and vice versa"
if isUnsafePointer(V) && (isPointer(Tu) || isUintptr(Tu)) {
if isUnsafePointer(Vu) && (isPointer(Tu) || isUintptr(Tu)) {
return true
}
// "V a slice, T is a pointer-to-array type,
// and the slice and array types have identical element types."
if s, _ := under(V).(*Slice); s != nil {
if p, _ := under(T).(*Pointer); p != nil {
if s, _ := Vu.(*Slice); s != nil {
if p, _ := Tu.(*Pointer); p != nil {
if a, _ := under(p.Elem()).(*Array); a != nil {
if Identical(s.Elem(), a.Elem()) {
if check == nil || check.allowVersion(check.pkg, 1, 17) {
@ -257,20 +257,12 @@ func (x *operand) convertibleTo(check *Checker, T Type, cause *string) bool {
return false
}
// Helper predicates for convertibleToImpl. The types provided to convertibleToImpl
// may be type parameters but they won't have specific type terms. Thus it is ok to
// use the toT convenience converters in the predicates below.
func isUintptr(typ Type) bool {
t, _ := under(typ).(*Basic)
return t != nil && t.kind == Uintptr
}
func isUnsafePointer(typ Type) bool {
// TODO(gri): Is this under(typ).(*Basic) instead of typ.(*Basic) correct?
// (The former calls under(), while the latter doesn't.)
// The spec does not say so, but gc claims it is. See also
// issue 6326.
t, _ := under(typ).(*Basic)
return t != nil && t.kind == UnsafePointer
}