Never create redirect for sourceFiles that get emitted to single output file

Fixes #30591

Author: sheetalkamat

src/compiler/program.ts

@@ -2266,8 +2266,13 @@ namespace ts {
 
             let redirectedPath: Path | undefined;
             if (refFile) {
-                const redirect = getProjectReferenceRedirect(fileName);
-                if (redirect) {
+                const redirectProject = getProjectReferenceRedirectProject(fileName);
+                if (redirectProject) {
+                    if (redirectProject.commandLine.options.outFile || redirectProject.commandLine.options.out) {
+                        // Shouldnt create many to 1 mapping file in --out scenario
+                        return undefined;
+                    }
+                    const redirect = getProjectReferenceOutputName(redirectProject, fileName);
                     fileName = redirect;
                     // Once we start redirecting to a file, we can potentially come back to it
                     // via a back-reference from another file in the .d.ts folder. If that happens we'll
@@ -2364,17 +2369,23 @@ namespace ts {
         }
 
         function getProjectReferenceRedirect(fileName: string): string | undefined {
+            const referencedProject = getProjectReferenceRedirectProject(fileName);
+            return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
+        }
+
+        function getProjectReferenceRedirectProject(fileName: string) {
             // Ignore dts or any of the non ts files
             if (!resolvedProjectReferences || !resolvedProjectReferences.length || fileExtensionIs(fileName, Extension.Dts) || !fileExtensionIsOneOf(fileName, supportedTSExtensions)) {
                 return undefined;
             }
 
             // If this file is produced by a referenced project, we need to rewrite it to
             // look in the output folder of the referenced project rather than the input
-            const referencedProject = getResolvedProjectReferenceToRedirect(fileName);
-            if (!referencedProject) {
-                return undefined;
-            }
+            return getResolvedProjectReferenceToRedirect(fileName);
+        }
+
+
+        function getProjectReferenceOutputName(referencedProject: ResolvedProjectReference, fileName: string) {
             const out = referencedProject.commandLine.options.outFile || referencedProject.commandLine.options.out;
             return out ?
                 changeExtension(out, Extension.Dts) :

src/testRunner/unittests/tsbuild/amdModulesWithOut.ts

@@ -233,7 +233,14 @@ ${internal} export enum internalEnum { a, b, c }`);
                     ],
                     lastProjectOutputJs: outputFiles[project.app][ext.js],
                     initialBuild: {
-                        modifyFs
+                        modifyFs,
+                        expectedDiagnostics: [
+                            getExpectedDiagnosticForProjectsInBuild("src/lib/tsconfig.json", "src/app/tsconfig.json"),
+                            [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/lib/tsconfig.json", "src/module.js"],
+                            [Diagnostics.Building_project_0, sources[project.lib][source.config]],
+                            [Diagnostics.Project_0_is_out_of_date_because_output_file_1_does_not_exist, "src/app/tsconfig.json", "src/app/module.js"],
+                            [Diagnostics.Building_project_0, sources[project.app][source.config]],
+                        ]
                     },
                     outputFiles: [
                         ...libOutputFile,