Select committed validation inputs by module

internal/validation/validation.go

@@ -4,6 +4,7 @@ package validation
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"go/format"
 	"io"
@@ -19,6 +20,7 @@ type Settings struct {
 	Race               bool
 	FullVet            bool
 	CompileTargets     []Target
+	SharedFiles        []string
 	GoFormat           bool
 	Markdown           *MarkdownSettings
 	ModuleDistribution ModuleDistributionSettings
@@ -51,6 +53,7 @@ type Target struct {
 // Request identifies the captured source and output used by shared validation.
 type Request struct {
 	RepositoryDir string
+	ModuleDir     string
 	Commit        string
 	Output        io.Writer
 	Settings      Settings
@@ -59,7 +62,10 @@ type Request struct {
 // ReadCandidateTree loads the committed-file inventory when a selected check
 // needs file-oriented input.
 func (request Request) ReadCandidateTree(ctx context.Context) (*CandidateTree, error) {
-	return ReadCandidateTree(ctx, request.RepositoryDir, request.Commit)
+	return ReadCandidateTreeForScope(ctx, request.RepositoryDir, request.Commit, TreeScope{
+		ModuleDir:   request.ModuleDir,
+		SharedFiles: request.Settings.SharedFiles,
+	})
 }
 
 // Run executes shared validation for the captured candidate.
@@ -118,9 +124,14 @@ func Run(ctx context.Context, request Request) (result error) {
 			}
 		}
 	}
-	if request.Settings.GoFormat || request.Settings.ModuleDistribution.WorkspaceFiles || request.Settings.ModuleDistribution.LocalReplacements || request.Settings.FileSize != nil || request.Settings.Markdown != nil {
+	needsSharedSelection := len(request.Settings.SharedFiles) != 0
+	if request.Settings.GoFormat || request.Settings.ModuleDistribution.WorkspaceFiles || request.Settings.ModuleDistribution.LocalReplacements || request.Settings.FileSize != nil || request.Settings.Markdown != nil || needsSharedSelection {
 		tree, err := request.ReadCandidateTree(ctx)
 		if err != nil {
+			var failure *Failure
+			if errors.As(err, &failure) {
+				return failure
+			}
 			check := MarkdownLinks
 			if request.Settings.FileSize != nil {
 				check = FileSize