fix bare specifier resolution order for paths without baseUrl

RealColdFry · RealColdFry · commit f0981dfa3435 · 2026-04-02T23:00:49.000+01:00
diff --git a/src/transpilation/resolve.ts b/src/transpilation/resolve.ts
@@ -209,14 +209,27 @@ class ResolutionContext {
             if (resolvedNodeModulesFile) return resolvedNodeModulesFile;
         }
 
+        const isRelativeDependency = ts.isExternalModuleNameRelative(dependencyPath);
+
+        if (!isRelativeDependency && this.options.paths) {
+            // Bare specifiers: check paths mappings first, matching TypeScript's resolution order.
+            // When baseUrl is not set, resolve paths relative to the tsconfig directory (TS 6.0+ behavior)
+            const pathsBase =
+                this.options.baseUrl ??
+                (this.options.configFilePath ? path.dirname(this.options.configFilePath) : undefined);
+            if (pathsBase) {
+                const fileFromPaths = this.tryGetModuleNameFromPaths(dependencyPath, this.options.paths, pathsBase);
+                if (fileFromPaths) return fileFromPaths;
+            }
+        }
+
         // Check if file is a file in the project
         const resolvedPath = this.formatPathToFile(dependencyPath, requiringFile);
         const fileFromPath = this.getFileFromPath(resolvedPath);
         if (fileFromPath) return fileFromPath;
 
-        if (this.options.paths) {
-            // If no file found yet and paths are present, try to find project file via paths mappings
-            // When baseUrl is not set, resolve paths relative to the tsconfig directory (TS 6.0+ behavior)
+        if (isRelativeDependency && this.options.paths) {
+            // Relative imports are still file-relative first; fall back to paths afterwards.
             const pathsBase =
                 this.options.baseUrl ??
                 (this.options.configFilePath ? path.dirname(this.options.configFilePath) : undefined);
diff --git a/test/transpile/module-resolution/paths-simple/myprogram/tsconfig.json b/test/transpile/module-resolution/paths-simple/myprogram/tsconfig.json
@@ -1,5 +1,7 @@
 {
     "compilerOptions": {
+        "baseUrl": ".",
+        "ignoreDeprecations": "6.0",
         "rootDir": "..",
         "outDir": "dist",
         "paths": {
diff --git a/test/unit/language-extensions/multi.spec.ts b/test/unit/language-extensions/multi.spec.ts
@@ -41,7 +41,7 @@ test("Destructuring assignment of LuaMultiReturn returning nil", () => {
         const [a, ...b] = multiReturn();
         export {a, b};
     `
-        .ignoreDiagnostics([2322, 2461])
+        .ignoreDiagnostics([2322, 2461]) // TS2322: bare return not assignable to LuaMultiReturn; TS2461: not iterable
         .withLanguageExtensions()
         .expectToEqual({ a: undefined, b: [] });
 });
diff --git a/test/unit/modules/resolution.spec.ts b/test/unit/modules/resolution.spec.ts
@@ -174,3 +174,20 @@ test("import = require", () => {
         .setOptions({ module: ts.ModuleKind.CommonJS })
         .tap(expectToRequire("foo.bar"));
 });
+
+test("paths without baseUrl resolves bare imports before sibling files", () => {
+    util.testModule`
+        import * as pkg from "pkg";
+        pkg;
+    `
+        .setMainFileName("/virtual/app/main.ts")
+        .addExtraFile("/virtual/app/pkg.ts", "export const sibling = true;")
+        .addExtraFile("/virtual/shared/pkg.ts", "export const mapped = true;")
+        .setOptions({
+            baseUrl: undefined,
+            configFilePath: "/virtual/tsconfig.json",
+            paths: { pkg: ["./shared/pkg"] },
+            rootDir: "/virtual",
+        })
+        .tap(expectToRequire("shared.pkg"));
+});
diff --git a/test/unit/precedingStatements.spec.ts b/test/unit/precedingStatements.spec.ts
@@ -108,6 +108,7 @@ describe("execution order", () => {
             );
             return result;
         `
+            // TS2783: duplicate property in spread — intentional, testing execution order
             .ignoreDiagnostics([2783])
             .expectToMatchJsResult();
     });
diff --git a/test/unit/spread.spec.ts b/test/unit/spread.spec.ts
@@ -116,6 +116,7 @@ describe("in object literal", () => {
         "{ ...{ x: false }, x: true }",
         "{ ...{ x: false }, x: false, ...{ x: true } }",
     ])("of object literal (%p)", expression => {
+        // TS2783: duplicate property in spread — intentional, testing spread override behavior
         util.testExpression(expression).ignoreDiagnostics([2783]).expectToMatchJsResult();
     });
 

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,7 @@`
`1`	`1`	`{`
`2`	`2`	`"compilerOptions": {`
	`3`	`+ "baseUrl": ".",`
	`4`	`+ "ignoreDeprecations": "6.0",`
`3`	`5`	`"rootDir": "..",`
`4`	`6`	`"outDir": "dist",`
`5`	`7`	`"paths": {`
Original file line number	Diff line number	Diff line change
`@@ -41,7 +41,7 @@ test("Destructuring assignment of LuaMultiReturn returning nil", () => {`
`41`	`41`	`const [a, ...b] = multiReturn();`
`42`	`42`	`export {a, b};`
`43`	`43`	`
`44`		`- .ignoreDiagnostics([2322, 2461])`
	`44`	`+ .ignoreDiagnostics([2322, 2461]) // TS2322: bare return not assignable to LuaMultiReturn; TS2461: not iterable`
`45`	`45`	`.withLanguageExtensions()`
`46`	`46`	`.expectToEqual({ a: undefined, b: [] });`
`47`	`47`	`});`
Original file line number	Diff line number	Diff line change
`@@ -108,6 +108,7 @@ describe("execution order", () => {`
`108`	`108`	`);`
`109`	`109`	`return result;`
`110`	`110`	`
	`111`	`+ // TS2783: duplicate property in spread — intentional, testing execution order`
`111`	`112`	`.ignoreDiagnostics([2783])`
`112`	`113`	`.expectToMatchJsResult();`
`113`	`114`	`});`