If import is used in the file, prefer that import specifier over calculating new one

src/compiler/checker.ts

@@ -4395,6 +4395,7 @@ namespace ts {
                         getProjectReferenceRedirect: fileName => host.getProjectReferenceRedirect(fileName),
                         isSourceOfProjectReferenceRedirect: fileName => host.isSourceOfProjectReferenceRedirect(fileName),
                         fileExists: fileName => host.fileExists(fileName),
+                        getFileIncludeReasons: () => host.getFileIncludeReasons(),
                     } : undefined },
                     encounteredError: false,
                     visitedTypes: undefined,

src/compiler/emitter.ts

@@ -849,7 +849,8 @@ namespace ts {
             useCaseSensitiveFileNames: () => host.useCaseSensitiveFileNames(),
             getProgramBuildInfo: returnUndefined,
             getSourceFileFromReference: returnUndefined,
-            redirectTargetsMap: createMultiMap()
+            redirectTargetsMap: createMultiMap(),
+            getFileIncludeReasons: notImplemented,
         };
         emitFiles(
             notImplementedResolver,

src/compiler/moduleSpecifiers.ts

@@ -104,8 +104,21 @@ namespace ts.moduleSpecifiers {
         const info = getInfo(importingSourceFile.path, host);
         const moduleSourceFile = getSourceFileOfNode(moduleSymbol.valueDeclaration || getNonAugmentationDeclaration(moduleSymbol));
         const modulePaths = getAllModulePaths(importingSourceFile.path, moduleSourceFile.originalFileName, host);
-
         const preferences = getPreferences(userPreferences, compilerOptions, importingSourceFile);
+
+        const existingSpecifier = forEach(modulePaths, modulePath => forEach(
+            host.getFileIncludeReasons().get(toPath(modulePath.path, host.getCurrentDirectory(), info.getCanonicalFileName)),
+            reason => {
+                if (reason.kind !== FileIncludeKind.Import || reason.file !== importingSourceFile.path) return undefined;
+                const specifier = getModuleNameStringLiteralAt(importingSourceFile, reason.index).text;
+                // If the preference is for non relative and the module specifier is relative, ignore it
+                return preferences.relativePreference !== RelativePreference.NonRelative || !pathIsRelative(specifier) ?
+                    specifier :
+                    undefined;
+            }
+        ));
+        if (existingSpecifier) return [existingSpecifier];
+
         const importedFileIsInNodeModules = some(modulePaths, p => p.isInNodeModules);
 
         // Module specifier priority:

src/compiler/program.ts

@@ -1649,6 +1649,7 @@ namespace ts {
                 getProgramBuildInfo: () => program.getProgramBuildInfo && program.getProgramBuildInfo(),
                 getSourceFileFromReference: (file, ref) => program.getSourceFileFromReference(file, ref),
                 redirectTargetsMap,
+                getFileIncludeReasons: program.getFileIncludeReasons,
             };
         }
 
@@ -3968,7 +3969,8 @@ namespace ts {
         return res;
     }
 
-    function getModuleNameStringLiteralAt({ imports, moduleAugmentations }: SourceFile, index: number): StringLiteralLike {
+    /* @internal */
+    export function getModuleNameStringLiteralAt({ imports, moduleAugmentations }: SourceFile, index: number): StringLiteralLike {
         if (index < imports.length) return imports[index];
         let augIndex = imports.length;
         for (const aug of moduleAugmentations) {

src/compiler/types.ts

@@ -7953,6 +7953,7 @@ namespace ts {
         readonly redirectTargetsMap: RedirectTargetsMap;
         getProjectReferenceRedirect(fileName: string): string | undefined;
         isSourceOfProjectReferenceRedirect(fileName: string): boolean;
+        getFileIncludeReasons(): MultiMap<Path, FileIncludeReason>;
     }
 
     // Note: this used to be deprecated in our public API, but is still used internally

src/services/utilities.ts

@@ -1835,6 +1835,7 @@ namespace ts {
             getProjectReferenceRedirect: fileName => program.getProjectReferenceRedirect(fileName),
             isSourceOfProjectReferenceRedirect: fileName => program.isSourceOfProjectReferenceRedirect(fileName),
             getNearestAncestorDirectoryWithPackageJson: maybeBind(host, host.getNearestAncestorDirectoryWithPackageJson),
+            getFileIncludeReasons: () => program.getFileIncludeReasons(),
         };
     }
 

src/testRunner/unittests/tsbuild/declarationEmit.ts

@@ -75,5 +75,44 @@ declare type MyNominal<T, Name extends string> = T & {
             }),
             commandLineArgs: ["--b", "/src/solution/tsconfig.json", "--verbose"]
         });
+
+        verifyTsc({
+            scenario: "declarationEmit",
+            subScenario: "when declaration file used inferred type from referenced project",
+            fs: () => loadProjectFromFiles({
+                "/src/tsconfig.json": JSON.stringify({
+                    compilerOptions: {
+                        composite: true,
+                        baseUrl: ".",
+                        paths: { "@fluentui/*": ["packages/*/src"] }
+                    }
+                }),
+                "/src/packages/pkg1/src/index.ts": Utils.dedent`
+export interface IThing {
+  a: string;
+}
+export interface IThings {
+  thing1: IThing;
+}`,
+                "/src/packages/pkg1/tsconfig.json": JSON.stringify({
+                    extends: "../../tsconfig",
+                    compilerOptions: { outDir: "lib" },
+                    include: ["src"]
+                }),
+                "/src/packages/pkg2/src/index.ts": Utils.dedent`
+import { IThings } from '@fluentui/pkg1';
+export function fn4() {
+  const a: IThings = { thing1: { a: 'b' } };
+  return a.thing1;
+}`,
+                "/src/packages/pkg2/tsconfig.json": JSON.stringify({
+                    extends: "../../tsconfig",
+                    compilerOptions: { outDir: "lib" },
+                    include: ["src"],
+                    references: [{ path: "../pkg1" }]
+                }),
+            }),
+            commandLineArgs: ["--b", "/src/packages/pkg2/tsconfig.json", "--verbose"]
+        });
     });
 }

src/testRunner/unittests/tsserver/projectReferenceErrors.ts

@@ -149,7 +149,7 @@ fnErr();
                             { line: 4, offset: 5 },
                             { line: 4, offset: 10 },
                             Diagnostics.Module_0_has_no_exported_member_1,
-                            [`"../dependency/fns"`, "fnErr"],
+                            [`"../decls/fns"`, "fnErr"],
                             "error",
                         )
                     ],

tests/baselines/reference/declarationEmitWithInvalidPackageJsonTypings.js

@@ -45,4 +45,4 @@ export interface MutableRefObject<T> {
     current: T;
 }
 export declare function useRef<T>(current: T): MutableRefObject<T>;
-export declare const useCsvParser: () => MutableRefObject<typeof import("csv-parse/lib")>;
+export declare const useCsvParser: () => MutableRefObject<typeof import("csv-parse")>;

tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport1.errors.txt

@@ -1,9 +1,9 @@
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(3,27): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(5,27): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(7,27): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(7,30): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(9,27): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
-tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(11,27): error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'm'. Did you mean to use 'import m from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(3,27): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(5,27): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(7,27): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(7,30): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(9,27): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(11,27): error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'm'. Did you mean to use 'import m from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
 
 
 ==== tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_0.ts (0 errors) ====
@@ -15,24 +15,24 @@ tests/cases/compiler/es6ImportDefaultBindingFollowedWithNamedImport1_1.ts(11,27)
     var x1: number = defaultBinding1;
     import defaultBinding2, { a } from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
                               ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
     var x1: number = defaultBinding2;
     import defaultBinding3, { a as b } from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
                               ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
     var x1: number = defaultBinding3;
     import defaultBinding4, { x, a as y } from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
                               ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
                                  ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'a'. Did you mean to use 'import a from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
     var x1: number = defaultBinding4;
     import defaultBinding5, { x as z,  } from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
                               ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'x'. Did you mean to use 'import x from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
     var x1: number = defaultBinding5;
     import defaultBinding6, { m,  } from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
                               ~
-!!! error TS2614: Module '"./es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'm'. Did you mean to use 'import m from "./es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
+!!! error TS2614: Module '"es6ImportDefaultBindingFollowedWithNamedImport1_0"' has no exported member 'm'. Did you mean to use 'import m from "es6ImportDefaultBindingFollowedWithNamedImport1_0"' instead?
     var x1: number = defaultBinding6;