fix #913: tsconfig "baseUrl" override of "paths"

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Fix a discrepancy with esbuild's `tsconfig.json` implementation ([#913](https://github.com/evanw/esbuild/issues/913))
+
+    If a `tsconfig.json` file contains a `"baseUrl"` value and `"extends"` another `tsconfig.json` file that contains a `"paths"` value, the base URL used for interpreting the paths should be the overridden value. Previously esbuild incorrectly used the inherited value, but with this release esbuild will now use the overridden value instead.
+
 * Work around the Jest testing framework breaking node's `Buffer` API ([#914](https://github.com/evanw/esbuild/issues/914))
 
     Running esbuild within a Jest test fails because Jest causes `Buffer` instances to not be considered `Uint8Array` instances, which then breaks the code esbuild uses to communicate with its child process. More info is here: https://github.com/facebook/jest/issues/4422. This release contains a workaround that copies each `Buffer` object into a `Uint8Array` object when this invariant is broken. That should prevent esbuild from crashing when it's run from within a Jest test.

internal/bundler/bundler_tsconfig_test.go

@@ -380,6 +380,116 @@ Users/user/project/tsconfig.json: warning: Non-relative path "http://bad" is not
 	})
 }
 
+// https://github.com/evanw/esbuild/issues/913
+func TestTsConfigPathsOverriddenBaseURL(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.ts": `
+				import test from '#/test'
+				console.log(test)
+			`,
+			"/Users/user/project/src/test.ts": `
+				export default 123
+			`,
+			"/Users/user/project/tsconfig.json": `
+				{
+					"extends": "./tsconfig.paths.json",
+					"compilerOptions": {
+						"baseUrl": "./src"
+					}
+				}
+			`,
+			"/Users/user/project/tsconfig.paths.json": `
+				{
+					"compilerOptions": {
+						"paths": {
+							"#/*": ["./*"]
+						}
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.ts"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+	})
+}
+
+func TestTsConfigPathsOverriddenBaseURLDifferentDir(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.ts": `
+				import test from '#/test'
+				console.log(test)
+			`,
+			"/Users/user/project/src/test.ts": `
+				export default 123
+			`,
+			"/Users/user/project/src/tsconfig.json": `
+				{
+					"extends": "../tsconfig.paths.json",
+					"compilerOptions": {
+						"baseUrl": "./"
+					}
+				}
+			`,
+			"/Users/user/project/tsconfig.paths.json": `
+				{
+					"compilerOptions": {
+						"paths": {
+							"#/*": ["./*"]
+						}
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.ts"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+	})
+}
+
+func TestTsConfigPathsMissingBaseURL(t *testing.T) {
+	tsconfig_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/Users/user/project/src/entry.ts": `
+				import test from '#/test'
+				console.log(test)
+			`,
+			"/Users/user/project/src/test.ts": `
+				export default 123
+			`,
+			"/Users/user/project/src/tsconfig.json": `
+				{
+					"extends": "../tsconfig.paths.json",
+					"compilerOptions": {
+					}
+				}
+			`,
+			"/Users/user/project/tsconfig.paths.json": `
+				{
+					"compilerOptions": {
+						"paths": {
+							"#/*": ["./*"]
+						}
+					}
+				}
+			`,
+		},
+		entryPaths: []string{"/Users/user/project/src/entry.ts"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/Users/user/project/out.js",
+		},
+		expectedScanLog: `Users/user/project/src/entry.ts: error: Could not resolve "#/test" (mark it as external to exclude it from the bundle)
+`,
+	})
+}
+
 func TestTsConfigJSX(t *testing.T) {
 	tsconfig_suite.expectBundled(t, bundled{
 		files: map[string]string{

internal/bundler/snapshots/snapshots_tsconfig.txt

@@ -178,6 +178,24 @@ var extended_default = {
 // Users/user/project/entry.ts
 console.log(simple_default, extended_default);
 
+================================================================================
+TestTsConfigPathsOverriddenBaseURL
+---------- /Users/user/project/out.js ----------
+// Users/user/project/src/test.ts
+var test_default = 123;
+
+// Users/user/project/src/entry.ts
+console.log(test_default);
+
+================================================================================
+TestTsConfigPathsOverriddenBaseURLDifferentDir
+---------- /Users/user/project/out.js ----------
+// Users/user/project/src/test.ts
+var test_default = 123;
+
+// Users/user/project/src/entry.ts
+console.log(test_default);
+
 ================================================================================
 TestTsconfigJsonAbsoluteBaseUrl
 ---------- /Users/user/project/out.js ----------

internal/resolver/resolver.go

@@ -1242,14 +1242,23 @@ func (r *resolver) loadAsFileOrDirectory(path string, kind ast.ImportKind) (Path
 // This closely follows the behavior of "tryLoadModuleUsingPaths()" in the
 // official TypeScript compiler
 func (r *resolver) matchTSConfigPaths(tsConfigJSON *TSConfigJSON, path string, kind ast.ImportKind) (PathPair, bool, *fs.DifferentCase) {
+	absBaseURL := tsConfigJSON.BaseURLForPaths
+
+	// The explicit base URL should take precedence over the implicit base URL
+	// if present. This matters when a tsconfig.json file overrides "baseUrl"
+	// from another extended tsconfig.json file but doesn't override "paths".
+	if tsConfigJSON.BaseURL != nil {
+		absBaseURL = *tsConfigJSON.BaseURL
+	}
+
 	// Check for exact matches first
 	for key, originalPaths := range tsConfigJSON.Paths {
 		if key == path {
 			for _, originalPath := range originalPaths {
 				// Load the original path relative to the "baseUrl" from tsconfig.json
 				absoluteOriginalPath := originalPath
 				if !r.fs.IsAbs(originalPath) {
-					absoluteOriginalPath = r.fs.Join(tsConfigJSON.BaseURLForPaths, originalPath)
+					absoluteOriginalPath = r.fs.Join(absBaseURL, originalPath)
 				}
 				if absolute, ok, diffCase := r.loadAsFileOrDirectory(absoluteOriginalPath, kind); ok {
 					return absolute, true, diffCase
@@ -1302,7 +1311,7 @@ func (r *resolver) matchTSConfigPaths(tsConfigJSON *TSConfigJSON, path string, k
 			// Load the original path relative to the "baseUrl" from tsconfig.json
 			absoluteOriginalPath := originalPath
 			if !r.fs.IsAbs(originalPath) {
-				absoluteOriginalPath = r.fs.Join(tsConfigJSON.BaseURLForPaths, originalPath)
+				absoluteOriginalPath = r.fs.Join(absBaseURL, originalPath)
 			}
 			if absolute, ok, diffCase := r.loadAsFileOrDirectory(absoluteOriginalPath, kind); ok {
 				return absolute, true, diffCase