feat: build of shared/static libraries

* add the correct extension according to the lib type and target os
* archive the generated header file

internal/artifact/artifact.go

@@ -66,6 +66,8 @@ const (
 	ScoopManifest
 	// SBOM is a Software Bill of Materials file.
 	SBOM
+	// Header is a C header file, generated for CGo library builds.
+	Header
 )
 
 func (t Type) String() string {
@@ -104,6 +106,8 @@ func (t Type) String() string {
 		return "PKGBUILD"
 	case SrcInfo:
 		return "SRCINFO"
+	case Header:
+		return "Header"
 	default:
 		return "unknown"
 	}

internal/builders/golang/build.go

@@ -192,6 +192,8 @@ func (*Builder) Build(ctx *context.Context, build config.Build, options api.Opti
 		}
 	}
 
+	addHeaderArtifactIfLibrary(ctx, build, options)
+
 	ctx.Artifacts.Add(artifact)
 	return nil
 }
@@ -366,3 +368,32 @@ func hasMain(file *ast.File) bool {
 	}
 	return false
 }
+
+func addHeaderArtifactIfLibrary(ctx *context.Context, build config.Build, options api.Options) {
+	for _, s := range build.BuildDetails.Flags {
+		if s == "-buildmode=c-shared" || s == "-buildmode=c-archive" {
+			fullPathWithoutExt := strings.TrimSuffix(options.Path, options.Ext)
+			basePath := filepath.Base(fullPathWithoutExt)
+			fullPath := fullPathWithoutExt + ".h"
+			headerName := basePath + ".h"
+
+			header := &artifact.Artifact{
+				Type:    artifact.Header,
+				Path:    fullPath,
+				Name:    headerName,
+				Goos:    options.Goos,
+				Goarch:  options.Goarch,
+				Goamd64: options.Goamd64,
+				Goarm:   options.Goarm,
+				Gomips:  options.Gomips,
+				Extra: map[string]interface{}{
+					artifact.ExtraBinary: headerName,
+					artifact.ExtraExt:    ".h",
+					artifact.ExtraID:     build.ID,
+				},
+			}
+
+			ctx.Artifacts.Add(header)
+		}
+	}
+}

internal/pipe/archive/archive.go

@@ -91,6 +91,7 @@ func (Pipe) Run(ctx *context.Context) error {
 		filter := []artifact.Filter{artifact.Or(
 			artifact.ByType(artifact.Binary),
 			artifact.ByType(artifact.UniversalBinary),
+			artifact.ByType(artifact.Header),
 		)}
 		if len(archive.Builds) > 0 {
 			filter = append(filter, artifact.ByIDs(archive.Builds...))

internal/pipe/build/build.go

@@ -212,6 +212,26 @@ func buildOptionsForTarget(ctx *context.Context, build config.Build, target stri
 }
 
 func extFor(target string, flags config.FlagArray) string {
+	if strings.Contains(target, "darwin") {
+		for _, s := range flags {
+			if s == "-buildmode=c-shared" {
+				return ".dylib"
+			}
+			if s == "-buildmode=c-archive" {
+				return ".a"
+			}
+		}
+	}
+	if strings.Contains(target, "linux") {
+		for _, s := range flags {
+			if s == "-buildmode=c-shared" {
+				return ".so"
+			}
+			if s == "-buildmode=c-archive" {
+				return ".a"
+			}
+		}
+	}
 	if strings.Contains(target, "windows") {
 		for _, s := range flags {
 			if s == "-buildmode=c-shared" {

internal/pipe/build/build_test.go

@@ -426,6 +426,26 @@ func TestSkipBuild(t *testing.T) {
 	require.Len(t, ctx.Artifacts.List(), 0)
 }
 
+func TestExtDarwin(t *testing.T) {
+	require.Equal(t, "", extFor("darwin_amd64", config.FlagArray{}))
+	require.Equal(t, "", extFor("darwin_arm64", config.FlagArray{}))
+	require.Equal(t, "", extFor("darwin_amd64", config.FlagArray{"-tags=dev", "-v"}))
+	require.Equal(t, ".dylib", extFor("darwin_amd64", config.FlagArray{"-tags=dev", "-v", "-buildmode=c-shared"}))
+	require.Equal(t, ".dylib", extFor("darwin_arm64", config.FlagArray{"-buildmode=c-shared"}))
+	require.Equal(t, ".a", extFor("darwin_amd64", config.FlagArray{"-buildmode=c-archive"}))
+	require.Equal(t, ".a", extFor("darwin_arm64", config.FlagArray{"-tags=dev", "-v", "-buildmode=c-archive"}))
+}
+
+func TestExtLinux(t *testing.T) {
+	require.Equal(t, "", extFor("linux_amd64", config.FlagArray{}))
+	require.Equal(t, "", extFor("linux_386", config.FlagArray{}))
+	require.Equal(t, "", extFor("linux_amd64", config.FlagArray{"-tags=dev", "-v"}))
+	require.Equal(t, ".so", extFor("linux_amd64", config.FlagArray{"-tags=dev", "-v", "-buildmode=c-shared"}))
+	require.Equal(t, ".so", extFor("linux_386", config.FlagArray{"-buildmode=c-shared"}))
+	require.Equal(t, ".a", extFor("linux_amd64", config.FlagArray{"-buildmode=c-archive"}))
+	require.Equal(t, ".a", extFor("linux_386", config.FlagArray{"-tags=dev", "-v", "-buildmode=c-archive"}))
+}
+
 func TestExtWindows(t *testing.T) {
 	require.Equal(t, ".exe", extFor("windows_amd64", config.FlagArray{}))
 	require.Equal(t, ".exe", extFor("windows_386", config.FlagArray{}))

www/docs/customization/build.md

@@ -517,3 +517,24 @@ will evaluate to the list of first class ports as defined in the Go wiki.
 
 You can read more about it
 [here](https://github.com/golang/go/wiki/PortingPolicy#first-class-ports).
+
+## Building shared or static libraries
+
+GoReleaser supports compiling and releasing libraries, by configuring the [Go build mode](https://pkg.go.dev/cmd/go#hdr-Build_modes).
+
+This can be set with `buildmode` in your build `flags`. It currently supports `c-shared` and `c-archive`.
+
+GoReleaser will:
+
+* set the correct file extension for the target OS.
+* package the generated header file (`.h`) in the release bundle.
+
+```yaml
+# .goreleaser.yaml
+builds:
+  -
+    id: "my-library"
+
+    # Configure the buildmode flag to output a shared library
+    flags: -buildmode=c-shared  # or "c-archive" for a static library
+```