Fix workspace/symbol crash on an inferred project without a program

tsc/internal/fourslash/tests/workspaceSymbolNewInferredProject_test.go

@@ -0,0 +1,57 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/TypeScript/tsc/internal/fourslash"
+	"github.com/microsoft/TypeScript/tsc/internal/lsp/lsproto"
+	"github.com/microsoft/TypeScript/tsc/internal/testutil"
+)
+
+// workspace/symbol used to crash when an open file got kicked out of its tsconfig project
+// and then another file from that project was opened. The orphaned file ends up in a fresh
+// inferred project, and nothing was building a program for it. Before that, the orphaned
+// file's symbols were missing because loading project trees didn't refresh the inferred project.
+func TestWorkspaceSymbolNewInferredProject(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `
+// @Filename: /home/src/projects/p/tsconfig.json
+// @noOpen: true
+{ "files": ["a.ts", "b.ts"] }
+
+// @Filename: /home/src/projects/p/a.ts
+import "./e";
+
+// @Filename: /home/src/projects/p/b.ts
+// @noOpen: true
+export const b = 1;
+
+// @Filename: /home/src/projects/p/e.ts
+export const e = 1;
+`
+	f, done := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	defer done()
+
+	// e.ts isn't listed in tsconfig.json, it only gets pulled in by the import in a.ts.
+	// Once that import is gone, e.ts should move to the inferred project.
+	f.GoToFile(t, "/home/src/projects/p/a.ts")
+	f.Replace(t, 0, len(`import "./e";`), "")
+	f.VerifyWorkspaceSymbol(t, []*fourslash.VerifyWorkspaceSymbolCase{
+		{Pattern: "b", Includes: new([]*lsproto.SymbolInformation{})},
+		{Pattern: "e", Includes: new([]*lsproto.SymbolInformation{{
+			Name: "e",
+			Kind: lsproto.SymbolKindVariable,
+			Location: lsproto.Location{
+				Uri:   "file:///home/src/projects/p/e.ts",
+				Range: lsproto.Range{Start: lsproto.Position{Line: 0, Character: 13}, End: lsproto.Position{Line: 0, Character: 14}},
+			},
+		}})},
+	})
+
+	// The tsconfig project is already up to date, so opening b.ts takes the fast path.
+	f.GoToFile(t, "/home/src/projects/p/b.ts")
+	f.VerifyWorkspaceSymbol(t, []*fourslash.VerifyWorkspaceSymbolCase{
+		{Pattern: "b", Includes: new([]*lsproto.SymbolInformation{})},
+	})
+}

tsc/internal/project/projectcollectionbuilder.go

@@ -760,6 +760,13 @@ func (b *ProjectCollectionBuilder) DidRequestProjectTrees(projectTreeRequest *Pr
 	}
 	wg.RunAndWait()
 
+	// Updated configured projects may have moved open files in or out of the inferred project.
+	// Callers iterate over all language service projects, so the inferred one needs a program too.
+	b.cleanupInferredProject(logger)
+	if b.inferredProject.Value() != nil {
+		b.updateProgram(b.inferredProject, logger)
+	}
+
 	if logger != nil {
 		elapsed := time.Since(startTime)
 		logger.Log(fmt.Sprintf("Completed project tree request for %v in %v", projectTreeRequest.Projects(), elapsed))