feat: codegen version check (#259)

Author: sysulq

Taskfile.yml

@@ -40,6 +40,7 @@ tasks:
         -covermode=atomic ./... ./tests/... \
         -coverpkg .,./cmd/...,./internal/...,./interceptor/...
       git checkout tests/case1/kod_gen_mock.go
+      git checkout tests/graphcase/kod_gen.go
     sources:
       - "**/**.go"
     generates:

cmd/kod/internal/generate_generator.go

@@ -22,6 +22,7 @@ import (
 	"golang.org/x/tools/go/packages"
 
 	"github.com/go-kod/kod/internal/callgraph"
+	"github.com/go-kod/kod/internal/version"
 )
 
 const (
@@ -562,19 +563,14 @@ func (g *generator) generate() error {
 		return nil
 	}
 
-	// // Process components in deterministic order.
-	// sort.Slice(g.components, func(i, j int) bool {
-	// 	return g.components[i].intfName() < g.components[j].intfName()
-	// })
-
 	// Generate the file body.
 	var body bytes.Buffer
 	{
 		fn := func(format string, args ...interface{}) {
 			fmt.Fprintln(&body, fmt.Sprintf(format, args...))
 		}
-		// g.generateVersionCheck(fn)
 		g.generateRegisteredComponents(fn)
+		g.generateVersionCheck(fn)
 		g.generateInstanceChecks(fn)
 		g.generateLocalStubs(fn)
 
@@ -678,6 +674,32 @@ func (g *generator) generateFullMethodNames(p printFn) {
 	p(`)`)
 }
 
+func (g *generator) generateVersionCheck(p printFn) {
+	selfVersion := version.SelfVersion()
+
+	p(``)
+	p(`// CodeGen version check.`)
+	p("var _ kod.CodeGenLatestVersion = kod.CodeGenVersion[[%d][%d]struct{}](%s)",
+		version.CodeGenMajor, version.CodeGenMinor,
+		fmt.Sprintf("`"+`
+ERROR: You generated this file with 'kod generate' %s (codegen
+version %s). The generated code is incompatible with the version of the
+github.com/go-kod/kod module that you're using. The kod module
+version can be found in your go.mod file or by running the following command.
+
+    go list -m github.com/go-kod/kod
+
+We recommend updating the kod module and the 'kod generate' command by
+running the following.
+
+    go get github.com/go-kod/kod@latest
+    go install github.com/go-kod/kod/cmd/kod@latest
+
+Then, re-run 'kod generate' and re-build your code. If the problem persists,
+please file an issue at https://github.com/go-kod/kod/issues.
+`+"`", selfVersion, version.CodeGenSemVersion))
+}
+
 // generateInstanceChecks generates code that checks that every component
 // implementation type implements kod.InstanceOf[T] for the appropriate T.
 func (g *generator) generateInstanceChecks(p printFn) {

examples/helloworld/kod_gen.go

@@ -0,0 +1,38 @@
+package version
+
+import (
+	"fmt"
+	"runtime/debug"
+
+	"github.com/samber/lo"
+)
+
+const (
+	// CodeGenMajor is the major version of the generated code.
+	CodeGenMajor = 0
+	// CodeGenMinor is the minor version of the generated code.
+	CodeGenMinor = 1
+	// codeGenPatch is the patch version of the generated code.
+	codeGenPatch = 0
+)
+
+// CodeGenSemVersion is the version of the generated code.
+var CodeGenSemVersion = SemVer{Major: CodeGenMajor, Minor: CodeGenMinor, Patch: codeGenPatch}
+
+// SemVer represents a semantic version.
+type SemVer struct {
+	Major int
+	Minor int
+	Patch int
+}
+
+// String returns the string representation of the semantic version.
+func (v SemVer) String() string {
+	return fmt.Sprintf("v%d.%d.%d", v.Major, v.Minor, v.Patch)
+}
+
+// SelfVersion returns the version of the running tool binary.
+func SelfVersion() string {
+	info := lo.Must(debug.ReadBuildInfo())
+	return info.Main.Version
+}

internal/version/version.go

@@ -0,0 +1,14 @@
+package kod
+
+import (
+	"github.com/go-kod/kod/internal/version"
+)
+
+// The following types are used to check, at compile time, that every
+// kod_gen.go file uses the codegen API version that is linked into the binary.
+type (
+	// CodeGenVersion is the version of the codegen API.
+	CodeGenVersion[_ any] string
+	// CodeGenLatestVersion is the latest version of the codegen API.
+	CodeGenLatestVersion = CodeGenVersion[[version.CodeGenMajor][version.CodeGenMinor]struct{}]
+)