Fix file rename crashes when dealing with solution configuration files (#4067)

Author: DanielRosenwasser

internal/fourslash/tests/getEditsForFileRenameWithSolutionConfigFile_test.go

@@ -0,0 +1,48 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/fourslash"
+	"github.com/microsoft/typescript-go/internal/testutil"
+)
+
+func TestGetEditsForFileRenameWithSolutionConfigFile(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	// The parent-directory solution tsconfig only references the composite child
+	// project, so when the child file is opened the solution is created as an
+	// ancestor project without ever building its program (it stays nil). Renaming
+	// a file in the child project must not crash when iterating that nil-program
+	// solution project.
+	const content = `
+// @Filename: /tsconfig.json
+{
+  "files": [],
+  "references": [
+    { "path": "./src/tsconfig.json" }
+  ]
+}
+
+// @Filename: /src/tsconfig.json
+{
+  "compilerOptions": {
+    "composite": true
+  },
+  "files": ["./a.ts", "./b.ts"]
+}
+
+// @Filename: /src/a.ts
+import { b } from "./b";
+b;
+
+// @Filename: /src/b.ts
+export const b = 0;`
+	f, done := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	defer done()
+	f.VerifyWillRenameFilesEdits(t, "/src/b.ts", "/src/c.ts", map[string]string{
+		"/src/a.ts": `import { b } from "./c";
+b;
+`,
+	}, nil /*preferences*/)
+}

internal/project/session.go

@@ -1025,7 +1025,12 @@ func (s *Session) GetLanguageServicesForDocuments(ctx context.Context, uris []ls
 	projects := snapshot.ProjectCollection.Projects()
 	services := make([]*ls.LanguageService, 0, len(projects))
 	for _, project := range projects {
-		services = append(services, ls.NewLanguageService(project.configFilePath, project.GetProgram(), snapshot, activeFile))
+		program := project.GetProgram()
+		if program == nil {
+			continue
+		}
+
+		services = append(services, ls.NewLanguageService(project.configFilePath, program, snapshot, activeFile))
 	}
 	return services
 }