[go] go/types, types2: fix string to type parameter conversions
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Robert Griesemer (Gerrit)
Feb 27, 2022, 9:23:22 PM2/27/22
to goph...@pubsubhelper.golang.org, Robert Griesemer, golang-co...@googlegroups.com
Robert Griesemer has uploaded this change for review.
go/types, types2: fix string to type parameter conversions
Converting an untyped constant to a type parameter results
in a non-constant value; but the constant must still be
representable by all specific types of the type parameter.
Adjust the special handling for constant-to-type parameter
conversions to also include string-to-[]byte and []rune
conversions, which are handled separately for conversions
to types that are not type parameters because those are not
constant conversions in non-generic code.
Fixes #51386.
Change-Id: I15e5a0fd281efd15af387280cd3dee320a1ac5e1
---
M src/cmd/compile/internal/types2/conversions.go
A src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
M src/go/types/conversions.go
A src/go/types/testdata/fixedbugs/issue51386.go2
4 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 7fe1d50..f3e95fd 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -19,8 +19,10 @@
constConvertibleTo := func(T Type, val *constant.Value) bool {
switch t, _ := under(T).(*Basic); {
+ case isString(x.typ) && isBytesOrRunes(T):
+ return true
case t == nil:
- // nothing to do
+ return false // exit early: T is not a basic type
case representableConst(x.val, check, t, val):
return true
case isInteger(x.typ) && isString(t):
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
new file mode 100644
index 0000000..ef622392
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
@@ -0,0 +1,17 @@
+// Copyright 2022 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.
+
+package p
+
+type myString string
+
+func _[P ~string | ~[]byte | ~[]rune]() {
+ _ = P("")
+ const s myString = ""
+ _ = P(s)
+}
+
+func _[P myString]() {
+ _ = P("")
+}
diff --git a/src/go/types/conversions.go b/src/go/types/conversions.go
index 8474135..058adab 100644
--- a/src/go/types/conversions.go
+++ b/src/go/types/conversions.go
@@ -18,8 +18,10 @@
constConvertibleTo := func(T Type, val *constant.Value) bool {
switch t, _ := under(T).(*Basic); {
+ case isString(x.typ) && isBytesOrRunes(T):
+ return true
case t == nil:
- // nothing to do
+ return false // exit early: T is not a basic type
case representableConst(x.val, check, t, val):
return true
case isInteger(x.typ) && isString(t):
diff --git a/src/go/types/testdata/fixedbugs/issue51386.go2 b/src/go/types/testdata/fixedbugs/issue51386.go2
new file mode 100644
index 0000000..ef622392
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue51386.go2
@@ -0,0 +1,17 @@
+// Copyright 2022 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.
+
+package p
+
+type myString string
+
+func _[P ~string | ~[]byte | ~[]rune]() {
+ _ = P("")
+ const s myString = ""
+ _ = P(s)
+}
+
+func _[P myString]() {
+ _ = P("")
+}
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Robert Findley (Gerrit)
Feb 28, 2022, 9:58:10 AM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, Gopher Robot, golang-co...@googlegroups.com
Attention is currently required from: Robert Griesemer.
Patch set 1:Code-Review +2
2 comments:
File src/go/types/conversions.go:
case isString(x.typ) && isBytesOrRunes(T):
return trueThis looks out of place here, since the rest of this function is about representability.
But I agree it fixes the bug.
Patch Set #1, Line 58:
if !constConvertibleTo(u, nil)I don't quite recall why we wouldn't just call x.convertibleTo here, based on the description above. Could use some explanation.
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Robert Griesemer (Gerrit)
Feb 28, 2022, 1:13:52 PM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, Robert Findley, Gopher Robot, golang-co...@googlegroups.com
2 comments:
File src/go/types/conversions.go:
case isString(x.typ) && isBytesOrRunes(T):
return true
This looks out of place here, since the rest of this function is about representability. […]
Agreed. But it was the easiest change to make. I'll see if I can make this clearer.
(Also note that this case is not reachable when we convert to a constant type (byte and rune slices are not constant types.)
Patch Set #1, Line 58:
if !constConvertibleTo(u, nil)
I don't quite recall why we wouldn't just call x.convertibleTo here, based on the description above. […]
The explanation is on line 47ff. Without that requirement - which is written down in the spec and which we need because upon monomorphization we have a single type - we could simply drop this entire case in the switch and the code would type-check.
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Robert Griesemer (Gerrit)
Feb 28, 2022, 1:20:34 PM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, golang-co...@googlegroups.com
Robert Griesemer uploaded patch set #2 to this change.
go/types, types2: fix string to type parameter conversions
Converting an untyped constant to a type parameter results
in a non-constant value; but the constant must still be
representable by all specific types of the type parameter.
Adjust the special handling for constant-to-type parameter
conversions to also include string-to-[]byte and []rune
conversions, which are handled separately for conversions
to types that are not type parameters because those are not
constant conversions in non-generic code.
Fixes #51386.
Change-Id: I15e5a0fd281efd15af387280cd3dee320a1ac5e1
---
M src/cmd/compile/internal/types2/conversions.go
A src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
M src/go/types/conversions.go
A src/go/types/testdata/fixedbugs/issue51386.go2
4 files changed, 63 insertions(+), 2 deletions(-)
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Robert Griesemer (Gerrit)
Feb 28, 2022, 1:20:56 PM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, Robert Findley, Gopher Robot, golang-co...@googlegroups.com
1 comment:
Patchset:
PTAL
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Robert Findley (Gerrit)
Feb 28, 2022, 2:05:43 PM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, Gopher Robot, golang-co...@googlegroups.com
Attention is currently required from: Robert Griesemer.
Patch set 2:Code-Review +2
2 comments:
File src/go/types/conversions.go:
case isString(x.typ) && isBytesOrRunes(T):
return true
(Also note that this case is not reachable when we convert to a constant type (byte and rune slices are not constant types.)
Yep, I observed that, but it looked fragile. New patchset looks better to me.
Patch Set #1, Line 58:
if !constConvertibleTo(u, nil)
The explanation is on line 47ff. […]
Ack, thanks for the additional explanation.
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Robert Griesemer (Gerrit)
Feb 28, 2022, 4:50:58 PM2/28/22
to Robert Griesemer, goph...@pubsubhelper.golang.org, golang-...@googlegroups.com, Gopher Robot, Robert Findley, golang-co...@googlegroups.com
Robert Griesemer submitted this change.
2 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
Approvals:
Robert Findley: Looks good to me, approved
Robert Griesemer: Trusted
go/types, types2: fix string to type parameter conversions
Converting an untyped constant to a type parameter results
in a non-constant value; but the constant must still be
representable by all specific types of the type parameter.
Adjust the special handling for constant-to-type parameter
conversions to also include string-to-[]byte and []rune
conversions, which are handled separately for conversions
to types that are not type parameters because those are not
constant conversions in non-generic code.
Fixes #51386.
Change-Id: I15e5a0fd281efd15af387280cd3dee320a1ac5e1
Reviewed-on: https://go-review.googlesource.com/c/go/+/388254
Trust: Robert Griesemer <g...@golang.org>
Reviewed-by: Robert Findley <rfin...@google.com>
---
M src/cmd/compile/internal/types2/conversions.go
A src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
M src/go/types/conversions.go
A src/go/types/testdata/fixedbugs/issue51386.go2
4 files changed, 66 insertions(+), 2 deletions(-)
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 7fe1d50..08b3cbf 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -49,11 +49,14 @@
// have specific types, constant x cannot be
// converted.
ok = T.(*TypeParam).underIs(func(u Type) bool {
- // t is nil if there are no specific type terms
+ // u is nil if there are no specific type terms
if u == nil {
cause = check.sprintf("%s does not contain specific types", T)
return false
}
+ if isString(x.typ) && isBytesOrRunes(u) {
+ return true
+ }
if !constConvertibleTo(u, nil) {
cause = check.sprintf("cannot convert %s to %s (in %s)", x, u, T)
return false
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
new file mode 100644
index 0000000..ef622392
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51386.go2
@@ -0,0 +1,17 @@
+// Copyright 2022 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.
+
+package p
+
+type myString string
+
+func _[P ~string | ~[]byte | ~[]rune]() {
+ _ = P("")
+ const s myString = ""
+ _ = P(s)
+}
+
+func _[P myString]() {
+ _ = P("")
+}
diff --git a/src/go/types/conversions.go b/src/go/types/conversions.go
index 8474135..c5a69cd 100644
--- a/src/go/types/conversions.go
+++ b/src/go/types/conversions.go
@@ -48,11 +48,14 @@
// have specific types, constant x cannot be
// converted.
ok = T.(*TypeParam).underIs(func(u Type) bool {
- // t is nil if there are no specific type terms
+ // u is nil if there are no specific type terms
if u == nil {
cause = check.sprintf("%s does not contain specific types", T)
return false
}
+ if isString(x.typ) && isBytesOrRunes(u) {
+ return true
+ }
if !constConvertibleTo(u, nil) {
cause = check.sprintf("cannot convert %s to %s (in %s)", x, u, T)
return false
diff --git a/src/go/types/testdata/fixedbugs/issue51386.go2 b/src/go/types/testdata/fixedbugs/issue51386.go2
new file mode 100644
index 0000000..ef622392
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue51386.go2
@@ -0,0 +1,17 @@
+// Copyright 2022 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.
+
+package p
+
+type myString string
+
+func _[P ~string | ~[]byte | ~[]rune]() {
+ _ = P("")
+ const s myString = ""
+ _ = P(s)
+}
+
+func _[P myString]() {
+ _ = P("")
+}
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