WIP: allow circular project references

src/compiler/program.ts

@@ -500,7 +500,8 @@ export function createCompilerHostWorker(options: CompilerOptions, setParentNode
         realpath,
         readDirectory: (path, extensions, include, exclude, depth) => system.readDirectory(path, extensions, include, exclude, depth),
         createDirectory: d => system.createDirectory(d),
-        createHash: maybeBind(system, system.createHash)
+        createHash: maybeBind(system, system.createHash),
+        useSourceOfProjectReferenceRedirect: (projectReferences) => projectReferences?.some(x => x.circular) || false,
     };
     return compilerHost;
 }
@@ -1671,7 +1672,7 @@ export function createProgram(rootNamesOrOptions: readonly string[] | CreateProg
     let mapFromFileToProjectReferenceRedirects: Map<Path, Path> | undefined;
     let mapFromToProjectReferenceRedirectSource: Map<Path, SourceOfProjectReferenceRedirect> | undefined;
 
-    const useSourceOfProjectReferenceRedirect = !!host.useSourceOfProjectReferenceRedirect?.() &&
+    const useSourceOfProjectReferenceRedirect = !!host.useSourceOfProjectReferenceRedirect?.(projectReferences) &&
         !options.disableSourceOfProjectReferenceRedirect;
     const { onProgramCreateComplete, fileExists, directoryExists } = updateHostForUseSourceOfProjectReferenceRedirect({
         compilerHost: host,

src/compiler/tsbuildPublic.ts

@@ -631,6 +631,9 @@ function createBuildOrder<T extends BuilderProgram>(state: SolutionBuilderState<
         const parsed = parseConfigFile(state, configFileName, projPath);
         if (parsed && parsed.projectReferences) {
             for (const ref of parsed.projectReferences) {
+                if (ref.circular) {
+                    continue;
+                }
                 const resolvedRefPath = resolveProjectName(state, ref.path);
                 visit(resolvedRefPath, inCircularContext || ref.circular);
             }

src/compiler/types.ts

@@ -7820,7 +7820,7 @@ export interface CompilerHost extends ModuleResolutionHost {
     /** @internal */ hasChangedAutomaticTypeDirectiveNames?: HasChangedAutomaticTypeDirectiveNames;
     createHash?(data: string): string;
     getParsedCommandLine?(fileName: string): ParsedCommandLine | undefined;
-    /** @internal */ useSourceOfProjectReferenceRedirect?(): boolean;
+    /** @internal */ useSourceOfProjectReferenceRedirect?(projectReferences: readonly ProjectReference[] | undefined): boolean;
 
     // TODO: later handle this in better way in builder host instead once the api for tsbuild finalizes and doesn't use compilerHost as base
     /** @internal */createDirectory?(directory: string): void;

src/compiler/watch.ts

@@ -767,6 +767,7 @@ export function createCompilerHostFromProgramHost(host: ProgramHost<any>, getCom
         createHash: maybeBind(host, host.createHash),
         readDirectory: maybeBind(host, host.readDirectory),
         storeFilesChangingSignatureDuringEmit: host.storeFilesChangingSignatureDuringEmit,
+        useSourceOfProjectReferenceRedirect: (projectReferences) => projectReferences?.some(x => x.circular) || false,
     };
     return compilerHost;
 }

src/testRunner/unittests/tsbuild/demo.ts

@@ -42,6 +42,26 @@ describe("unittests:: tsbuild:: on demo project", () => {
   ]`
         )
     });
+
+    verifyTsc({
+        scenario: "demo",
+        subScenario: "in explicit circular branch reports no error",
+        fs: () => projFs,
+        commandLineArgs: ["--b", "/src/tsconfig.json", "--verbose"],
+        modifyFs: fs => replaceText(
+            fs,
+            "/src/core/tsconfig.json",
+            "}",
+            `},
+  "references": [
+    {
+      "path": "../zoo",
+      "circular": true
+    }
+  ]`
+        )
+    });
+
     verifyTsc({
         scenario: "demo",
         subScenario: "in bad-ref branch reports the error about files not in rootDir at the import location",