[dev.typeparams] go/types: implement delete(m, k) where m is of type parameter type

This is a port of CL 333729 to go/types.

Change-Id: I8682f549a7a15124b1b338f8c73e83a57d138368
Reviewed-on: https://go-review.googlesource.com/c/go/+/335078
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index c8348f425917d06b1916a675177dccbd1feab29d..eb3503fd6b5533631bf907a7ca2f1b1b28d72e85 100644 (file)
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -369,25 +369,40 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
                x.typ = Typ[Int]
 
        case _Delete:
-               // delete(m, k)
-               m := asMap(x.typ)
-               if m == nil {
-                       check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+               // delete(map_, key)
+               // map_ must be a map type or a type parameter describing map types.
+               // The key cannot be a type parameter for now.
+               map_ := x.typ
+               var key Type
+               if !underIs(map_, func(u Type) bool {
+                       map_, _ := u.(*Map)
+                       if map_ == nil {
+                               check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
+                               return false
+                       }
+                       if key != nil && !Identical(map_.key, key) {
+                               check.invalidArg(x, _Todo, "maps of %s must have identical key types", x)
+                               return false
+                       }
+                       key = map_.key
+                       return true
+               }) {
                        return
                }
+
                arg(x, 1) // k
                if x.mode == invalid {
                        return
                }
 
-               check.assignment(x, m.key, "argument to delete")
+               check.assignment(x, key, "argument to delete")
                if x.mode == invalid {
                        return
                }
 
                x.mode = novalue
                if check.Types != nil {
-                       check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
+                       check.recordBuiltinType(call.Fun, makeSig(nil, map_, key))
                }
 
        case _Imag, _Real:

diff --git a/src/go/types/testdata/check/builtins.go2 b/src/go/types/testdata/check/builtins.go2
index 71295bf4342f78cdfcc0bd2420fce85e250b992a..8fe6d7b332e38a0e0813f277758bfe4cba778036 100644 (file)
--- a/src/go/types/testdata/check/builtins.go2
+++ b/src/go/types/testdata/check/builtins.go2
@@ -43,6 +43,43 @@ func _[T C5[X], X any](ch T) {
        close(ch)
 }
 
+// delete
+
+type M0 interface{ int }
+type M1 interface{ map[string]int }
+type M2 interface { map[string]int | map[string]float64 }
+type M3 interface{ map[string]int | map[rune]int }
+type M4[K comparable, V any] interface{ map[K]V | map[rune]V }
+
+func _[T any](m T) {
+       delete(m /* ERROR not a map */, "foo")
+}
+
+func _[T M0](m T) {
+       delete(m /* ERROR not a map */, "foo")
+}
+
+func _[T M1](m T) {
+       delete(m, "foo")
+}
+
+func _[T M2](m T) {
+       delete(m, "foo")
+       delete(m, 0 /* ERROR cannot use .* as string */)
+}
+
+func _[T M3](m T) {
+       delete(m /* ERROR must have identical key types */, "foo")
+}
+
+func _[T M4[rune, V], V any](m T) {
+       delete(m, 'k')
+}
+
+func _[T M4[K, V], K comparable, V any](m T) {
+       delete(m /* ERROR must have identical key types */, "foo")
+}
+
 // make
 
 type Bmc interface {

diff --git a/src/go/types/type.go b/src/go/types/type.go
index bbb7100ef4f6b639a67cf177e4dd35006b15ab67..b575b11e4e19a6ea73e8ddf36334ecae747e12f8 100644 (file)
--- a/src/go/types/type.go
+++ b/src/go/types/type.go
@@ -110,11 +110,6 @@ func asSignature(t Type) *Signature {
        return op
 }
 
-func asMap(t Type) *Map {
-       op, _ := optype(t).(*Map)
-       return op
-}
-
 // If the argument to asInterface, asNamed, or asTypeParam is of the respective type
 // (possibly after expanding an instance type), these methods return that type.
 // Otherwise the result is nil.