fix: support dir in gomod (#4729)

closes https://github.com/orgs/goreleaser/discussions/4728

internal/pipe/gomod/gomod.go

@@ -36,6 +36,9 @@ func (Pipe) Run(ctx *context.Context) error {
 	}
 	cmd := exec.CommandContext(ctx, ctx.Config.GoMod.GoBinary, flags...)
 	cmd.Env = append(ctx.Env.Strings(), ctx.Config.GoMod.Env...)
+	if dir := ctx.Config.GoMod.Dir; dir != "" {
+		cmd.Dir = dir
+	}
 	out, err := cmd.CombinedOutput()
 	result := strings.TrimSpace(string(out))
 	if strings.HasPrefix(result, goPreModulesError) {

internal/pipe/gomod/gomod_test.go

@@ -75,6 +75,29 @@ func TestCustomEnv(t *testing.T) {
 	require.NoError(t, Pipe{}.Run(ctx))
 }
 
+func TestRunCustomDir(t *testing.T) {
+	dir := testlib.Mktmp(t)
+	require.NoError(t, os.MkdirAll(filepath.Join(dir, "src"), 0o755))
+	require.NoError(t, os.WriteFile(
+		filepath.Join(dir, "src/main.go"),
+		[]byte("package main\nfunc main() {println(0)}"),
+		0o666,
+	))
+	require.NoError(t, os.WriteFile(
+		filepath.Join(dir, "src/go.mod"),
+		[]byte("module foo"),
+		0o666,
+	))
+	ctx := testctx.NewWithCfg(config.Project{
+		GoMod: config.GoMod{
+			Dir: filepath.Join(dir, "src"),
+		},
+	})
+	require.NoError(t, Pipe{}.Default(ctx))
+	require.NoError(t, Pipe{}.Run(ctx))
+	require.Equal(t, "foo", ctx.ModulePath)
+}
+
 func TestRunOutsideGoModule(t *testing.T) {
 	dir := testlib.Mktmp(t)
 	require.NoError(t, os.WriteFile(

pkg/config/config.go

@@ -1247,6 +1247,7 @@ type GoMod struct {
 	Env      []string `yaml:"env,omitempty" json:"env,omitempty"`
 	GoBinary string   `yaml:"gobinary,omitempty" json:"gobinary,omitempty"`
 	Mod      string   `yaml:"mod,omitempty" json:"mod,omitempty"`
+	Dir      string   `yaml:"dir,omitempty" json:"dir,omitempty"`
 }
 
 type Announce struct {

www/docs/customization/verifiable_builds.md

@@ -37,6 +37,12 @@ gomod:
   #
   # Default: `go`.
   gobinary: go1.17
+
+  # Directory in which the go.mod file is.
+  #
+  # Default: ''
+  # Since: v1.25
+  dir: ./src
 ```
 
 !!! tip
@@ -49,7 +55,7 @@ gomod:
     VCS Info will not be embedded in the binary, as in practice it is not being
     built from the source, but from the Go Mod Proxy.
 
-!!! warning 
+!!! warning
 
     If you have a `go.work` file, make sure to run `go work sync`, so the main
     module (`.`) is the first line inside the `use` block.