From 2fbf6aafe7de215a1d03e14aa488aa8fd31f56a7 Mon Sep 17 00:00:00 2001
From: Keith Randall <khr@golang.org>
Date: Mon, 9 Aug 2021 11:40:46 -0700
Subject: [PATCH] [dev.typeparams] cmd/compile: handle interface type
parameters in type switches
Change-Id: I9bba21a64d7e9f42395b6fcdf8aa3ca01cf131dc
Reviewed-on: https://go-review.googlesource.com/c/go/+/340912
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
---
src/cmd/compile/internal/noder/stencil.go | 30 ++++++++++--------
test/typeparam/typeswitch6.go | 30 ++++++++++++++++++
test/typeparam/typeswitch6.out | 5 +++
test/typeparam/typeswitch7.go | 37 +++++++++++++++++++++++
test/typeparam/typeswitch7.out | 3 ++
5 files changed, 93 insertions(+), 12 deletions(-)
create mode 100644 test/typeparam/typeswitch6.go
create mode 100644 test/typeparam/typeswitch6.out
create mode 100644 test/typeparam/typeswitch7.go
create mode 100644 test/typeparam/typeswitch7.out
diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 23e8090136..6736f128e3 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -1157,19 +1157,21 @@ func (subst *subster) node(n ir.Node) ir.Node {
assert(ix >= 0)
dt := ir.NewDynamicType(c.Pos(), getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen))
- // For type switch from nonemoty interfaces to non-interfaces, we need an itab as well.
- if _, ok := subst.info.gfInfo.type2switchType[c]; ok {
- // Type switch from nonempty interface. We need a *runtime.itab
- // for the dynamic type.
- ix := -1
- for i, ic := range subst.info.gfInfo.itabConvs {
- if ic == c {
- ix = subst.info.startItabConv + i
- break
+ // For type switch from nonempty interfaces to non-interfaces, we need an itab as well.
+ if !m.List[i].Type().IsInterface() {
+ if _, ok := subst.info.gfInfo.type2switchType[c]; ok {
+ // Type switch from nonempty interface. We need a *runtime.itab
+ // for the dynamic type.
+ ix := -1
+ for i, ic := range subst.info.gfInfo.itabConvs {
+ if ic == c {
+ ix = subst.info.startItabConv + i
+ break
+ }
}
+ assert(ix >= 0)
+ dt.ITab = getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
}
- assert(ix >= 0)
- dt.ITab = getDictionaryEntry(c.Pos(), subst.info.dictParam, ix, subst.info.dictLen)
}
typed(m.List[i].Type(), dt)
m.List[i] = dt
@@ -1484,6 +1486,8 @@ func (g *irgen) getDictionarySym(gf *ir.Name, targs []*types.Type, isMeth bool)
// instantiations have been created.
func (g *irgen) finalizeSyms() {
for _, d := range g.dictSymsToFinalize {
+ infoPrint("=== Finalizing dictionary %s\n", d.sym.Name)
+
lsym := d.sym.Linksym()
info := g.getGfInfo(d.gf)
@@ -1528,9 +1532,11 @@ func (g *irgen) finalizeSyms() {
// No itab is wanted if src type is an interface. We
// will use a type assert instead.
d.off = objw.Uintptr(lsym, d.off, 0)
+ infoPrint(" + Unused itab entry for %v\n", srctype)
} else {
itabLsym := reflectdata.ITabLsym(srctype, dsttype)
d.off = objw.SymPtr(lsym, d.off, itabLsym, 0)
+ infoPrint(" + Itab for (%v,%v)\n", srctype, dsttype)
}
}
@@ -1694,7 +1700,7 @@ func (g *irgen) getGfInfo(gn *ir.Name) *gfInfo {
for _, cc := range n.(*ir.SwitchStmt).Cases {
for _, c := range cc.List {
if c.Op() == ir.OTYPE && c.Type().HasTParam() {
- // Type switch from a non-empty interface to a noninterface.
+ // Type switch from a non-empty interface - might need an itab.
infoPrint(" Itab for type switch: %v\n", c)
info.itabConvs = append(info.itabConvs, c)
if info.type2switchType == nil {
diff --git a/test/typeparam/typeswitch6.go b/test/typeparam/typeswitch6.go
new file mode 100644
index 0000000000..574f4aa819
--- /dev/null
+++ b/test/typeparam/typeswitch6.go
@@ -0,0 +1,30 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 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 main
+
+func f[T any](i interface{}) {
+ switch i.(type) {
+ case T:
+ println("T")
+ case int:
+ println("int")
+ default:
+ println("other")
+ }
+}
+
+type myint int
+func (myint) foo() {
+}
+
+func main() {
+ f[interface{}](nil)
+ f[interface{}](6)
+ f[interface{foo()}](nil)
+ f[interface{foo()}](7)
+ f[interface{foo()}](myint(8))
+}
diff --git a/test/typeparam/typeswitch6.out b/test/typeparam/typeswitch6.out
new file mode 100644
index 0000000000..441add5ec5
--- /dev/null
+++ b/test/typeparam/typeswitch6.out
@@ -0,0 +1,5 @@
+other
+T
+other
+int
+T
diff --git a/test/typeparam/typeswitch7.go b/test/typeparam/typeswitch7.go
new file mode 100644
index 0000000000..f2e1279fb4
--- /dev/null
+++ b/test/typeparam/typeswitch7.go
@@ -0,0 +1,37 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 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 main
+
+func f[T any](i interface{foo()}) {
+ switch i.(type) {
+ case interface{bar() T}:
+ println("barT")
+ case myint:
+ println("myint")
+ case myfloat:
+ println("myfloat")
+ default:
+ println("other")
+ }
+}
+
+type myint int
+func (myint) foo() {
+}
+func (x myint) bar() int {
+ return int(x)
+}
+
+type myfloat float64
+func (myfloat) foo() {
+}
+
+func main() {
+ f[int](nil)
+ f[int](myint(6))
+ f[int](myfloat(7))
+}
diff --git a/test/typeparam/typeswitch7.out b/test/typeparam/typeswitch7.out
new file mode 100644
index 0000000000..d7fcad4fee
--- /dev/null
+++ b/test/typeparam/typeswitch7.out
@@ -0,0 +1,3 @@
+other
+barT
+myfloat