fix: non-relative path completion without baseUrl (#52908)

Author: jasonlyu123

src/services/stringCompletions.ts

@@ -54,6 +54,7 @@ import {
     getOwnKeys,
     getPackageJsonTypesVersionsPaths,
     getPathComponents,
+    getPathsBasePath,
     getReplacementSpanForContextToken,
     getResolvePackageJsonExports,
     getSupportedExtensions,
@@ -559,7 +560,7 @@ function getStringLiteralCompletionsFromModuleNamesWorker(sourceFile: SourceFile
     const scriptDirectory = getDirectoryPath(scriptPath);
     const extensionOptions = getExtensionOptions(compilerOptions, ReferenceKind.ModuleSpecifier, sourceFile, typeChecker, preferences, mode);
 
-    return isPathRelativeToScript(literalValue) || !compilerOptions.baseUrl && (isRootedDiskPath(literalValue) || isUrl(literalValue))
+    return isPathRelativeToScript(literalValue) || !compilerOptions.baseUrl && !compilerOptions.paths && (isRootedDiskPath(literalValue) || isUrl(literalValue))
         ? getCompletionEntriesForRelativeModules(literalValue, scriptDirectory, compilerOptions, host, scriptPath, extensionOptions)
         : getCompletionEntriesForNonRelativeModules(literalValue, scriptDirectory, mode, compilerOptions, host, extensionOptions, typeChecker);
 }
@@ -850,13 +851,15 @@ function getCompletionEntriesForNonRelativeModules(
 
     const result = createNameAndKindSet();
     const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
+
     if (baseUrl) {
-        const projectDir = compilerOptions.project || host.getCurrentDirectory();
-        const absolute = normalizePath(combinePaths(projectDir, baseUrl));
+        const absolute = normalizePath(combinePaths(host.getCurrentDirectory(), baseUrl));
         getCompletionEntriesForDirectoryFragment(fragment, absolute, extensionOptions, host, /*moduleSpecifierIsRelative*/ false, /*exclude*/ undefined, result);
-        if (paths) {
-            addCompletionEntriesFromPaths(result, fragment, absolute, extensionOptions, host, paths);
-        }
+    }
+
+    if (paths) {
+        const absolute = getPathsBasePath(compilerOptions, host)!;
+        addCompletionEntriesFromPaths(result, fragment, absolute, extensionOptions, host, paths);
     }
 
     const fragmentDirectory = getFragmentDirectory(fragment);

tests/cases/fourslash/completionForStringLiteralNonrelativeImport17.ts

@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts' />
+
+// Should give completions for modules referenced via baseUrl and paths compiler options with explicit name mappings
+
+// @Filename: tsconfig.json
+//// {
+////     "compilerOptions": {
+////         "paths": {
+////             "module1/*": ["some/path/*"],
+////         }
+////     }
+//// }
+
+// @Filename: test0.ts
+//// import * as foo1 from "module1/w/*first*/
+
+// @Filename: some/path/whatever.ts
+//// export {}
+
+verify.completions({ marker: ["first"], exact: "whatever", isNewIdentifierLocation: true });

tests/cases/fourslash/completionForStringLiteralNonrelativeImport18.ts

@@ -0,0 +1,20 @@
+/// <reference path='fourslash.ts' />
+
+// Should give completions for modules referenced via baseUrl and paths compiler options with explicit name mappings
+
+// @Filename: tsconfig.json
+//// {
+////     "compilerOptions": {
+////        "paths": {
+////            "/*": ["./*"]
+////        },
+////     }
+//// }
+
+// @Filename: test0.ts
+//// import * as foo1 from "/path/w/*first*/
+
+// @Filename: path/whatever.ts
+//// export {}
+
+verify.completions({ marker: ["first"], exact: ["whatever"], isNewIdentifierLocation: true });