deprecated reflect mode has been replaced with package mode (#207)

It is impossible to create an mock for a generic interface via reflect
mode, because it is impossible to compile a generic type without
instantiation.
This PR replaces the reflect mod for parsing using go/types.

All exists mocks have been regenerated and the tests have been passed.
But since this radically changes the behavior of reflect mode, I would
be grateful if there are those who want to add additional test cases
that I did not provide.

We can also come up with another name instead of import mode.

benefits:
generation mocks for generic interfaces
generation mocks for aliases to interfaces
correct names for method arguments

resolves #175
resolves #197
resolves #128
---------
Co-authored-by: Jacob Oaks <joaks@uber.com>

README.md

@@ -40,7 +40,7 @@ export PATH=$PATH:$(go env GOPATH)/bin
 
 ## Running mockgen
 
-`mockgen` has two modes of operation: source and reflect.
+`mockgen` has two modes of operation: source and package.
 
 ### Source mode
 
@@ -54,11 +54,10 @@ Example:
 mockgen -source=foo.go [other options]
 ```
 
-### Reflect mode
+### Package mode
 
-Reflect mode generates mock interfaces by building a program
-that uses reflection to understand interfaces. It is enabled
-by passing two non-flag arguments: an import path, and a
+Package mode works by specifying the package and interface names.
+It is enabled by passing two non-flag arguments: an import path, and a
 comma-separated list of symbols.
 
 You can use "." to refer to the current path's package.
@@ -98,7 +97,7 @@ It supports the following flags:
   `foo=bar/baz.go`, where `bar/baz.go` is the source file and `foo` is the
   package name of that file used by the -source file.
 
-- `-build_flags`: (reflect mode only) Flags passed verbatim to `go build`.
+- `-build_flags`: (package mode only) Flags passed verbatim to `go list`.
 
 - `-mock_names`: A list of custom names for generated mocks. This is specified
   as a comma-separated list of elements of the form
@@ -119,15 +118,11 @@ It supports the following flags:
 
 - `-debug_parser`: Print out parser results only.
 
-- `-exec_only`: (reflect mode) If set, execute this reflection program.
-
-- `-prog_only`: (reflect mode) Only generate the reflection program; write it to stdout and exit.
-
 - `-write_package_comment`: Writes package documentation comment (godoc) if true. (default true)
 
 - `-write_generate_directive`: Add //go:generate directive to regenerate the mock. (default false)
 
-- `-write_source_comment`: Writes original file (source mode) or interface names (reflect mode) comment if true. (default true)
+- `-write_source_comment`: Writes original file (source mode) or interface names (package mode) comment if true. (default true)
 
 - `-typed`: Generate Type-safe 'Return', 'Do', 'DoAndReturn' function. (default false)
 

go.mod

@@ -3,8 +3,15 @@ module go.uber.org/mock
 go 1.22
 
 require (
+	github.com/stretchr/testify v1.9.0
 	golang.org/x/mod v0.18.0
 	golang.org/x/tools v0.22.0
 )
 
-require github.com/yuin/goldmark v1.4.13 // indirect
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/yuin/goldmark v1.4.13 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -1,3 +1,9 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/yuin/goldmark v1.4.13 h1:fVcFKWvrslecOb/tg+Cc05dkeYx540o0FuFt3nUVDoE=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/mod v0.18.0 h1:5+9lSbEzPSdWkH32vYPBwEpX8KwDbM52Ud9xBUvNlb0=
@@ -6,3 +12,7 @@ golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
 golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/tools v0.22.0 h1:gqSGLZqv+AI9lIQzniJ0nZDRG5GBPsSi+DRNHWNz6yA=
 golang.org/x/tools v0.22.0/go.mod h1:aCwcsjqvq7Yqt6TNyX7QMU2enbQ/Gt0bo6krSeEri+c=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

mockgen/deprecated.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+)
+
+const (
+	deprecatedFlagProgOnly = "prog_only"
+	deprecatedFlagExecOnly = "exec_only"
+)
+
+var (
+	_ = flag.Bool("prog_only", false, "DEPRECATED (reflect mode) Only generate the reflection program; write it to stdout and exit.")
+	_ = flag.String("exec_only", "", "DEPRECATED (reflect mode) If set, execute this reflection program.")
+)
+
+// notifyAboutDeprecatedFlags prints a warning message for a deprecated flags if they are set.
+func notifyAboutDeprecatedFlags() {
+	const resetColorPostfix = "\033[0m"
+	logger := initWarningLogger()
+
+	flag.Visit(func(f *flag.Flag) {
+		switch f.Name {
+		case deprecatedFlagProgOnly:
+			logger.Println("The -prog_only flag is deprecated and has no effect.", resetColorPostfix)
+		case deprecatedFlagExecOnly:
+			logger.Println("The -exec_only flag is deprecated and has no effect.", resetColorPostfix)
+		}
+	})
+}
+
+func initWarningLogger() *log.Logger {
+	const (
+		yellowColor   = "\033[33m"
+		warningPrefix = yellowColor + "WARNING: "
+	)
+
+	return log.New(os.Stdout, warningPrefix, log.Ldate|log.Ltime)
+}

mockgen/internal/tests/build_flags/directive.go

@@ -0,0 +1,6 @@
+package build_flags
+
+// one build flag
+//go:generate mockgen -destination=mock1/interfaces_mock.go -build_flags=-tags=tag1 . Interface
+// multiple build flags
+//go:generate mockgen -destination=mock2/interfaces_mock.go "-build_flags=-race -tags=tag2" . Interface

mockgen/internal/tests/build_flags/interfaces_1.go

@@ -0,0 +1,7 @@
+//go:build tag1
+
+package build_flags
+
+type Interface interface {
+	HelloWorld() string
+}

mockgen/internal/tests/build_flags/interfaces_2.go

@@ -0,0 +1,7 @@
+//go:build tag2
+
+package build_flags
+
+type Interface interface {
+	Foo()
+}

mockgen/internal/tests/generics/external.go

@@ -9,6 +9,7 @@ import (
 )
 
 //go:generate mockgen --source=external.go --destination=source/mock_external_mock.go --package source
+//go:generate mockgen --destination=package_mode/mock_external_mock.go -package=package_mode . ExternalConstraint,EmbeddingIface,Generator,Group
 
 type ExternalConstraint[I constraints.Integer, F any] interface {
 	One(string) string

mockgen/internal/tests/generics/generics.go

@@ -6,7 +6,7 @@ import (
 )
 
 //go:generate mockgen --source=generics.go --destination=source/mock_generics_mock.go --package source
-////go:generate mockgen --destination=reflect/mock_test.go --package reflect . Bar,Bar2
+//go:generate mockgen --destination=package_mode/mock_test.go --package=package_mode . Bar,Universe,MilkyWay,SolarSystem,Earth,Water
 
 type Bar[T any, R any] interface {
 	One(string) string