support type-safe return values (#11)

migrate from golang/mock#630
more:
golang/mock#622 
golang/mock#427 
golang/mock#634 
golang/mock#657

---------

Co-authored-by: Sung Yoon Whang <sungyoonwhang@gmail.com>

README.md

@@ -113,6 +113,8 @@ It supports the following flags:
 
 - `-write_package_comment`: Writes package documentation comment (godoc) if true. (default true)
 
+- `-typed`: Generate Type-safe 'Return', 'Do', 'DoAndReturn' function. (default false)
+
 For an example of the use of `mockgen`, see the `sample/` directory. In simple
 cases, you will need only the `-source` flag.
 

mockgen/internal/tests/typed/bugreport.go

@@ -0,0 +1,18 @@
+package typed
+
+//go:generate mockgen -typed -aux_files faux=faux/faux.go -destination bugreport_mock.go -package typed -source=bugreport.go Example
+
+import (
+	"log"
+
+	"go.uber.org/mock/mockgen/internal/tests/typed/faux"
+)
+
+// Source is an interface w/ an embedded foreign interface
+type Source interface {
+	faux.Foreign
+}
+
+func CallForeignMethod(s Source) {
+	log.Println(s.Method())
+}

mockgen/internal/tests/typed/bugreport_test.go

@@ -0,0 +1,18 @@
+package typed
+
+import (
+	"testing"
+
+	"go.uber.org/mock/gomock"
+)
+
+// TestValidInterface assesses whether or not the generated mock is valid
+func TestValidInterface(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	s := NewMockSource(ctrl)
+	s.EXPECT().Method().Return("")
+
+	CallForeignMethod(s)
+}

mockgen/internal/tests/typed/external.go

@@ -0,0 +1,21 @@
+package typed
+
+import (
+	"go.uber.org/mock/mockgen/internal/tests/typed/other"
+	"golang.org/x/exp/constraints"
+)
+
+//go:generate mockgen --source=external.go --destination=source/mock_external_test.go --package source -typed
+
+type ExternalConstraint[I constraints.Integer, F constraints.Float] interface {
+	One(string) string
+	Two(I) string
+	Three(I) F
+	Four(I) Foo[I, F]
+	Five(I) Baz[F]
+	Six(I) *Baz[F]
+	Seven(I) other.One[I]
+	Eight(F) other.Two[I, F]
+	Nine(Iface[I])
+	Ten(*I)
+}

mockgen/internal/tests/typed/faux/faux.go

@@ -0,0 +1,11 @@
+package faux
+
+type Foreign interface {
+	Method() Return
+	Embedded
+	error
+}
+
+type Embedded interface{}
+
+type Return interface{}

mockgen/internal/tests/typed/generics.go

@@ -0,0 +1,40 @@
+package typed
+
+import "go.uber.org/mock/mockgen/internal/tests/typed/other"
+
+//go:generate mockgen --source=generics.go --destination=source/mock_generics_test.go --package source -typed
+////go:generate mockgen --destination=reflect/mock_test.go --package reflect . Bar,Bar2
+
+type Bar[T any, R any] interface {
+	One(string) string
+	Two(T) string
+	Three(T) R
+	Four(T) Foo[T, R]
+	Five(T) Baz[T]
+	Six(T) *Baz[T]
+	Seven(T) other.One[T]
+	Eight(T) other.Two[T, R]
+	Nine(Iface[T])
+	Ten(*T)
+	Eleven() (*other.One[T], error)
+	Twelve() (*other.Two[T, R], error)
+	Thirteen() (Baz[StructType], error)
+	Fourteen() (*Foo[StructType, StructType2], error)
+	Fifteen() (Iface[StructType], error)
+	Sixteen() (Baz[other.Three], error)
+	Seventeen() (*Foo[other.Three, other.Four], error)
+	Eighteen() (Iface[*other.Five], error)
+	Nineteen() AliasType
+}
+
+type Foo[T any, R any] struct{}
+
+type Baz[T any] struct{}
+
+type Iface[T any] interface{}
+
+type StructType struct{}
+
+type StructType2 struct{}
+
+type AliasType Baz[other.Three]

mockgen/internal/tests/typed/go.mod

@@ -0,0 +1,10 @@
+module go.uber.org/mock/mockgen/internal/tests/typed
+
+go 1.18
+
+replace go.uber.org/mock => ../../../..
+
+require (
+	go.uber.org/mock v0.0.0-00010101000000-000000000000
+	golang.org/x/exp v0.0.0-20220609121020-a51bd0440498
+)

mockgen/internal/tests/typed/go.sum

@@ -0,0 +1,26 @@
+github.com/yuin/goldmark v1.4.1/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/exp v0.0.0-20220609121020-a51bd0440498 h1:TF0FvLUGEq/8wOt/9AV1nj6D4ViZGUIGCMQfCv7VRXY=
+golang.org/x/exp v0.0.0-20220609121020-a51bd0440498/go.mod h1:yh0Ynu2b5ZUe3MQfp2nM0ecK7wsgouWTDN0FNeJuIys=
+golang.org/x/mod v0.5.1/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.8/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

mockgen/internal/tests/typed/other/other.go

@@ -0,0 +1,11 @@
+package other
+
+type One[T any] struct{}
+
+type Two[T any, R any] struct{}
+
+type Three struct{}
+
+type Four struct{}
+
+type Five interface{}