Add support for taking relative CLI args and using them as absolute internally - fixes microsoft#30457

Author: orta

src/compiler/commandLineParser.ts

@@ -675,7 +675,7 @@ namespace ts {
             name: "out",
             type: "string",
             affectsEmit: true,
-            isFilePath: false, // This is intentionally broken to support compatability with existing tsconfig files
+            isFilePath: false, // This is intentionally broken to support compatibility with existing tsconfig files
             // for correct behaviour, please use outFile
             category: Diagnostics.Advanced_Options,
             paramType: Diagnostics.FILE,
@@ -2058,6 +2058,7 @@ namespace ts {
 
         const parsedConfig = parseConfig(json, sourceFile, host, basePath, configFileName, resolutionStack, errors, extendedConfigCache);
         const { raw } = parsedConfig;
+        makeFilesReferencesAbsolute(existingOptions);
         const options = extend(existingOptions, parsedConfig.options || {});
         options.configFilePath = configFileName && normalizeSlashes(configFileName);
         setConfigFileInOptions(options, sourceFile);
@@ -2169,6 +2170,17 @@ namespace ts {
                 errors.push(createCompilerDiagnostic(message, arg0, arg1));
             }
         }
+
+        function makeFilesReferencesAbsolute(optionsFromCLI: CompilerOptions) {
+            Object.keys(optionsFromCLI).forEach(key => {
+                const optionForKey = getOptionDeclarationFromName(getOptionNameMap, key, /*allowShort*/ true);
+                const value = optionsFromCLI[key];
+                const relative = isString(value) && !isRootedDiskPath(value);
+                if (relative && optionForKey && optionForKey.isFilePath && configFileName) {
+                    optionsFromCLI[key] = getNormalizedAbsolutePath(value as string, getDirectoryPath(configFileName));
+                }
+            });
+        }
     }
 
     function isErrorNoInputFiles(error: Diagnostic) {

src/testRunner/unittests/config/tsconfigParsing.ts

@@ -381,5 +381,25 @@ namespace ts {
             const parsed = getParsedCommandJsonNode(jsonText, "/apath/tsconfig.json", "tests/cases/unittests", ["/apath/a.ts"]);
             assert.isTrue(parsed.errors.length >= 0);
         });
+
+        it("converts relative paths from the CLI to absolute paths internally based on the tsconfig", () => {
+            const existingOptions = {
+                rootDir: "src"
+            };
+
+            const jsonText = `{
+              "compilerOptions": {
+                "incremental": true,
+                "outDir": "dist"
+              }
+            }`;
+
+            const parsed = parseJsonText("/path/to/config.tsconfig", jsonText);
+            const files = ["/path/to/src/file.ts"].reduce((files, value) => (files[value] = "", files), {} as vfs.FileSet);
+            const host: ParseConfigHost = new fakes.ParseConfigHost(new vfs.FileSystem(/*ignoreCase*/ false, { cwd: ".", files: { "/": {}, ...files } }));
+            const config = parseJsonSourceFileConfigFileContent(parsed, host, ".", existingOptions, "/path/to/config.tsconfig");
+
+            assert.equal(config.options.rootDir, "/path/to/src");
+        });
     });
 }