internal/lsp: add quick fix for unsupported feature

Adds a command to run go mod edit -go to allow
users to easily upgrade their go directive.

Doing this change also revealed that changing
the go directive does not invalidate the type check
data and there may be stale diagnostics for a package.

Updates golang/go#51086

Change-Id: I659a216059c489a88e29cd51b944c3a0274f3700
Reviewed-on: https://go-review.googlesource.com/c/tools/+/386875
Trust: Suzy Mueller <suzmue@golang.org>
Run-TryBot: Suzy Mueller <suzmue@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

gopls/doc/commands.md

@@ -84,6 +84,22 @@ Args:
 }
 ```
 
+### **Run go mod edit -go=version**
+Identifier: `gopls.edit_go_directive`
+
+Runs `go mod edit -go=version` for a module.
+
+Args:
+
+```
+{
+	// Any document URI within the relevant module.
+	"URI": string,
+	// The version to pass to `go mod edit -go`.
+	"Version": string,
+}
+```
+
 ### **Toggle gc_details**
 Identifier: `gopls.gc_details`
 

internal/lsp/cache/errors.go

@@ -101,6 +101,7 @@ func parseErrorDiagnostics(snapshot *snapshot, pkg *pkg, errList scanner.ErrorLi
 }
 
 var importErrorRe = regexp.MustCompile(`could not import ([^\s]+)`)
+var unsupportedFeatureRe = regexp.MustCompile(`.*require go(\d+\.\d+) or later`)
 
 func typeErrorDiagnostics(snapshot *snapshot, pkg *pkg, e extendedError) ([]*source.Diagnostic, error) {
 	code, spn, err := typeErrorData(snapshot.FileSet(), pkg, e.primary)
@@ -145,6 +146,14 @@ func typeErrorDiagnostics(snapshot *snapshot, pkg *pkg, e extendedError) ([]*sou
 			return nil, err
 		}
 	}
+	if code == typesinternal.UnsupportedFeature {
+		if match := unsupportedFeatureRe.FindStringSubmatch(e.primary.Msg); match != nil {
+			diag.SuggestedFixes, err = editGoDirectiveQuickFix(snapshot, spn.URI(), match[1])
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
 	return []*source.Diagnostic{diag}, nil
 }
 
@@ -165,6 +174,22 @@ func goGetQuickFixes(snapshot *snapshot, uri span.URI, pkg string) ([]source.Sug
 	return []source.SuggestedFix{source.SuggestedFixFromCommand(cmd, protocol.QuickFix)}, nil
 }
 
+func editGoDirectiveQuickFix(snapshot *snapshot, uri span.URI, version string) ([]source.SuggestedFix, error) {
+	// Go mod edit only supports module mode.
+	if snapshot.workspaceMode()&moduleMode == 0 {
+		return nil, nil
+	}
+	title := fmt.Sprintf("go mod edit -go=%s", version)
+	cmd, err := command.NewEditGoDirectiveCommand(title, command.EditGoDirectiveArgs{
+		URI:     protocol.URIFromSpanURI(uri),
+		Version: version,
+	})
+	if err != nil {
+		return nil, err
+	}
+	return []source.SuggestedFix{source.SuggestedFixFromCommand(cmd, protocol.QuickFix)}, nil
+}
+
 func analysisDiagnosticDiagnostics(snapshot *snapshot, pkg *pkg, a *analysis.Analyzer, e *analysis.Diagnostic) ([]*source.Diagnostic, error) {
 	var srcAnalyzer *source.Analyzer
 	// Find the analyzer that generated this diagnostic.

internal/lsp/command.go

@@ -261,6 +261,20 @@ func (c *commandHandler) Vendor(ctx context.Context, args command.URIArg) error
 	})
 }
 
+func (c *commandHandler) EditGoDirective(ctx context.Context, args command.EditGoDirectiveArgs) error {
+	return c.run(ctx, commandConfig{
+		requireSave: true, // if go.mod isn't saved it could cause a problem
+		forURI:      args.URI,
+	}, func(ctx context.Context, deps commandDeps) error {
+		_, err := deps.snapshot.RunGoCommandDirect(ctx, source.Normal, &gocommand.Invocation{
+			Verb:       "mod",
+			Args:       []string{"edit", "-go", args.Version},
+			WorkingDir: filepath.Dir(args.URI.SpanURI().Filename()),
+		})
+		return err
+	})
+}
+
 func (c *commandHandler) RemoveDependency(ctx context.Context, args command.RemoveDependencyArgs) error {
 	return c.run(ctx, commandConfig{
 		progress: "Removing dependency",

internal/lsp/command/interface.go

@@ -68,6 +68,11 @@ type Interface interface {
 	// Runs `go mod vendor` for a module.
 	Vendor(context.Context, URIArg) error
 
+	// EditGoDirective: Run go mod edit -go=version
+	//
+	// Runs `go mod edit -go=version` for a module.
+	EditGoDirective(context.Context, EditGoDirectiveArgs) error
+
 	// UpdateGoSum: Update go.sum
 	//
 	// Updates the go.sum file for a module.
@@ -204,6 +209,13 @@ type RemoveDependencyArgs struct {
 	OnlyDiagnostic bool
 }
 
+type EditGoDirectiveArgs struct {
+	// Any document URI within the relevant module.
+	URI protocol.DocumentURI
+	// The version to pass to `go mod edit -go`.
+	Version string
+}
+
 type GoGetPackageArgs struct {
 	// Any document URI within the relevant module.
 	URI protocol.DocumentURI