expvar: add Delete function

Adds a `Delete` function to the expvar package to remove a named
exported variable. Calls `Map.Delete`.

Fixes #73814

Author: mhamza15

src/cmd/api/testdata/src/pkg/p1/golden.txt

@@ -1,6 +1,6 @@
+pkg p1, const A //deprecated
 pkg p1, const A = 1
 pkg p1, const A ideal-int
-pkg p1, const A //deprecated
 pkg p1, const A64 = 1
 pkg p1, const A64 int64
 pkg p1, const AIsLowerA = 11
@@ -25,8 +25,8 @@ pkg p1, func TakesFunc(func(int) int)
 pkg p1, method (*B) JustOnB()
 pkg p1, method (*B) OnBothTandBPtr()
 pkg p1, method (*Embedded) OnEmbedded()
-pkg p1, method (*S2) SMethod(int8, int16, int64)
 pkg p1, method (*S2) SMethod //deprecated
+pkg p1, method (*S2) SMethod(int8, int16, int64)
 pkg p1, method (*T) JustOnT()
 pkg p1, method (*T) OnBothTandBPtr()
 pkg p1, method (B) OnBothTandBVal()
@@ -53,8 +53,8 @@ pkg p1, type Error interface { Error, Temporary }
 pkg p1, type Error interface, Error() string
 pkg p1, type Error interface, Temporary() bool
 pkg p1, type FuncType func(int, int, string) (*B, error)
-pkg p1, type I interface, Get(string) int64
 pkg p1, type I interface, Get //deprecated
+pkg p1, type I interface, Get(string) int64
 pkg p1, type I interface, GetNamed(string) int64
 pkg p1, type I interface, Name() string
 pkg p1, type I interface, PackageTwoMeth()
@@ -63,9 +63,9 @@ pkg p1, type I interface, unexported methods
 pkg p1, type MyInt int
 pkg p1, type Namer interface { Name }
 pkg p1, type Namer interface, Name() string
+pkg p1, type Private //deprecated
 pkg p1, type Private interface, X()
 pkg p1, type Private interface, unexported methods
-pkg p1, type Private //deprecated
 pkg p1, type Public interface { X, Y }
 pkg p1, type Public interface, X()
 pkg p1, type Public interface, Y()
@@ -84,8 +84,8 @@ pkg p1, type TPtrExported struct
 pkg p1, type TPtrExported struct, embedded *Embedded
 pkg p1, type TPtrUnexported struct
 pkg p1, type Time struct
-pkg p1, type URL struct
 pkg p1, type URL //deprecated
+pkg p1, type URL struct
 pkg p1, var Byte uint8
 pkg p1, var ByteConv []uint8
 pkg p1, var ByteFunc func(uint8) int32
@@ -97,8 +97,8 @@ pkg p1, var StrConv string
 pkg p1, var V string
 pkg p1, var V1 uint64
 pkg p1, var V2 p2.Twoer
-pkg p1, var VError Error
 pkg p1, var VError //deprecated
+pkg p1, var VError Error
 pkg p1, var X I
 pkg p1, var X0 int64
 pkg p1, var Y int

src/cmd/api/testdata/src/pkg/p2/golden.txt

@@ -1,8 +1,7 @@
-pkg p2, func F() string
 pkg p2, func F //deprecated
+pkg p2, func F() string
 pkg p2, func G() Twoer
 pkg p2, func NewError(string) error
 pkg p2, type Twoer interface { PackageTwoMeth }
-pkg p2, type Twoer interface, PackageTwoMeth()
 pkg p2, type Twoer interface, PackageTwoMeth //deprecated
-
+pkg p2, type Twoer interface, PackageTwoMeth()

src/cmd/api/testdata/src/pkg/p4/golden.txt

@@ -1,6 +1,6 @@
+pkg p4, func Clone //deprecated
+pkg p4, func Clone[$0 interface{ ~[]$1 }, $1 interface{}]($0) $0
 pkg p4, func NewPair[$0 interface{ M }, $1 interface{ ~int }]($0, $1) Pair[$0, $1]
-pkg p4, method (Pair[$0, $1]) Second() $1
 pkg p4, method (Pair[$0, $1]) First() $0
+pkg p4, method (Pair[$0, $1]) Second() $1
 pkg p4, type Pair[$0 interface{ M }, $1 interface{ ~int }] struct
-pkg p4, func Clone[$0 interface{ ~[]$1 }, $1 interface{}]($0) $0
-pkg p4, func Clone //deprecated

src/expvar/expvar.go

@@ -316,6 +316,11 @@ func Publish(name string, v Var) {
 	slices.Sort(vars.keys)
 }
 
+// Delete removes a named exported variable.
+func Delete(name string) {
+	vars.Delete(name)
+}
+
 // Get retrieves a named exported variable. It returns nil if the name has
 // not been registered.
 func Get(name string) Var {