Add diagnostics to remind adding tsconfig file for certain external project

src/compiler/core.ts

@@ -1063,6 +1063,18 @@ namespace ts {
         };
     }
 
+    export function createCompilerDiagnosticFromMessageChain(chain: DiagnosticMessageChain): Diagnostic {
+        return {
+            file: undefined,
+            start: undefined,
+            length: undefined,
+
+            code: chain.code,
+            category: chain.category,
+            messageText: chain.next ? chain : chain.messageText
+        };
+    }
+
     export function chainDiagnosticMessages(details: DiagnosticMessageChain, message: DiagnosticMessage, ...args: any[]): DiagnosticMessageChain;
     export function chainDiagnosticMessages(details: DiagnosticMessageChain, message: DiagnosticMessage): DiagnosticMessageChain {
         let text = getLocaleSpecificMessage(message);

src/compiler/diagnosticMessages.json

@@ -3118,5 +3118,9 @@
     "Implement inherited abstract class": {
         "category": "Message",
         "code": 90007
+    },
+    "Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig": {
+        "category": "Error",
+        "code": 90009
     }
 }

src/compiler/program.ts

@@ -239,11 +239,11 @@ namespace ts {
                 const { line, character } = getLineAndCharacterOfPosition(diagnostic.file, diagnostic.start);
                 const fileName = diagnostic.file.fileName;
                 const relativeFileName = convertToRelativePath(fileName, host.getCurrentDirectory(), fileName => host.getCanonicalFileName(fileName));
-                output += `${ relativeFileName }(${ line + 1 },${ character + 1 }): `;
+                output += `${relativeFileName}(${line + 1},${character + 1}): `;
             }
 
             const category = DiagnosticCategory[diagnostic.category].toLowerCase();
-            output += `${ category } TS${ diagnostic.code }: ${ flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine()) }${ host.getNewLine() }`;
+            output += `${category} TS${diagnostic.code}: ${flattenDiagnosticMessageText(diagnostic.messageText, host.getNewLine())}${host.getNewLine()}`;
         }
         return output;
     }
@@ -1316,11 +1316,11 @@ namespace ts {
                     }
                     else if (shouldAddFile) {
                         findSourceFile(resolution.resolvedFileName,
-                                toPath(resolution.resolvedFileName, currentDirectory, getCanonicalFileName),
+                            toPath(resolution.resolvedFileName, currentDirectory, getCanonicalFileName),
                                 /*isDefaultLib*/ false,
-                                file,
-                                skipTrivia(file.text, file.imports[i].pos),
-                                file.imports[i].end);
+                            file,
+                            skipTrivia(file.text, file.imports[i].pos),
+                            file.imports[i].end);
                     }
 
                     if (isFromNodeModulesSearch) {
@@ -1537,13 +1537,21 @@ namespace ts {
                     const emitFilePath = toPath(emitFileName, currentDirectory, getCanonicalFileName);
                     // Report error if the output overwrites input file
                     if (filesByName.contains(emitFilePath)) {
-                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file);
+                        let chain: DiagnosticMessageChain;
+                        if (!options.configFilePath) {
+                            // The program is from either an inferred project or an external project
+                            chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Adding_a_tsconfig_json_file_will_help_organize_projects_that_contain_both_TypeScript_and_JavaScript_files_Learn_more_at_https_Colon_Slash_Slashaka_ms_Slashtsconfig);
+                        }
+                        chain = chainDiagnosticMessages(chain, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file, emitFileName);
+                        const diagnostic = createCompilerDiagnosticFromMessageChain(chain);
+                        createEmitBlockingDiagnostics(emitFileName, diagnostic);
                     }
 
                     // Report error if multiple files write into same file
                     if (emitFilesSeen.contains(emitFilePath)) {
                         // Already seen the same emit file - report error
-                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files);
+                        const diagnostic = createCompilerDiagnostic(Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files, emitFileName);
+                        createEmitBlockingDiagnostics(emitFileName, diagnostic);
                     }
                     else {
                         emitFilesSeen.set(emitFilePath, true);
@@ -1552,9 +1560,9 @@ namespace ts {
             }
         }
 
-        function createEmitBlockingDiagnostics(emitFileName: string, message: DiagnosticMessage) {
+        function createEmitBlockingDiagnostics(emitFileName: string, diag: Diagnostic) {
             hasEmitBlockingDiagnostics.set(toPath(emitFileName, currentDirectory, getCanonicalFileName), true);
-            programDiagnostics.add(createCompilerDiagnostic(message, emitFileName));
+            programDiagnostics.add(diag);
         }
     }
 }

src/harness/fourslash.ts

@@ -1274,7 +1274,19 @@ namespace FourSlash {
                             resultString += "Diagnostics:" + Harness.IO.newLine();
                             const diagnostics = ts.getPreEmitDiagnostics(this.languageService.getProgram());
                             for (let i = 0, n = diagnostics.length; i < n; i++) {
-                                resultString += "  " + diagnostics[0].messageText + Harness.IO.newLine();
+                                const diagnostic = diagnostics[i];
+                                if (typeof diagnostic.messageText !== "string") {
+                                    let chainedMessage = <ts.DiagnosticMessageChain>diagnostic.messageText;
+                                    let indentation = " ";
+                                    while (chainedMessage) {
+                                        resultString += indentation + chainedMessage.messageText + Harness.IO.newLine();
+                                        chainedMessage = chainedMessage.next;
+                                        indentation = indentation + " ";
+                                    }
+                                }
+                                else {
+                                    resultString += "  " + diagnostic.messageText + Harness.IO.newLine();
+                                }
                             }
                         }
 

tests/baselines/reference/compileOnSaveWorksWhenEmitBlockingErrorOnOtherFile.baseline

@@ -1,6 +1,7 @@
 EmitSkipped: true
 Diagnostics:
-  Cannot write file '/tests/cases/fourslash/b.js' because it would overwrite input file.
+ Cannot write file '/tests/cases/fourslash/b.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 EmitSkipped: false
 FileName : /tests/cases/fourslash/a.js

tests/baselines/reference/declarationFileOverwriteError.errors.txt

@@ -1,7 +1,9 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.d.ts' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.d.ts' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.d.ts (0 errors) ====
 
     declare class c {

tests/baselines/reference/declarationFileOverwriteErrorWithOut.errors.txt

@@ -1,7 +1,9 @@
 error TS5055: Cannot write file 'tests/cases/compiler/out.d.ts' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/out.d.ts' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/out.d.ts (0 errors) ====
 
     declare class c {

tests/baselines/reference/exportDefaultInJsFile01.errors.txt

@@ -1,7 +1,9 @@
 error TS5055: Cannot write file 'tests/cases/conformance/salsa/myFile01.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5055: Cannot write file 'tests/cases/conformance/salsa/myFile01.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/conformance/salsa/myFile01.js (0 errors) ====
 
     export default "hello";

tests/baselines/reference/exportDefaultInJsFile02.errors.txt

@@ -1,7 +1,9 @@
 error TS5055: Cannot write file 'tests/cases/conformance/salsa/myFile02.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5055: Cannot write file 'tests/cases/conformance/salsa/myFile02.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/conformance/salsa/myFile02.js (0 errors) ====
 
     export default "hello";

tests/baselines/reference/jsFileCompilationAmbientVarDeclarationSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,1): error TS8009: 'declare' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     declare var v;
     ~~~~~~~

tests/baselines/reference/jsFileCompilationEmitBlockedCorrectly.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 error TS5056: Cannot write file 'tests/cases/compiler/a.js' because it would be overwritten by multiple input files.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 !!! error TS5056: Cannot write file 'tests/cases/compiler/a.js' because it would be overwritten by multiple input files.
 ==== tests/cases/compiler/a.ts (0 errors) ====
     class c {

tests/baselines/reference/jsFileCompilationEnumSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,6): error TS8015: 'enum declarations' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     enum E { }
          ~

tests/baselines/reference/jsFileCompilationErrorOnDeclarationsWithJsFileReferenceWithNoOut.errors.txt

@@ -1,9 +1,11 @@
 error TS5053: Option 'allowJs' cannot be specified with option 'declaration'.
 error TS5055: Cannot write file 'tests/cases/compiler/c.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5053: Option 'allowJs' cannot be specified with option 'declaration'.
 !!! error TS5055: Cannot write file 'tests/cases/compiler/c.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.ts (0 errors) ====
     class c {
     }

tests/baselines/reference/jsFileCompilationExportAssignmentSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,1): error TS8003: 'export=' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     export = b;
     ~~~~~~~~~~~

tests/baselines/reference/jsFileCompilationHeritageClauseSyntaxOfClass.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,9): error TS8005: 'implements clauses' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     class C implements D { }
             ~~~~~~~~~~~~

tests/baselines/reference/jsFileCompilationImportEqualsSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,1): error TS8002: 'import ... =' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     import a = b;
     ~~~~~~~~~~~~~

tests/baselines/reference/jsFileCompilationInterfaceSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,11): error TS8006: 'interface declarations' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     interface I { }
               ~

tests/baselines/reference/jsFileCompilationModuleSyntax.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,8): error TS8007: 'module declarations' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     module M { }
            ~

tests/baselines/reference/jsFileCompilationNoErrorWithoutDeclarationsWithJsFileReferenceWithNoOut.errors.txt

@@ -1,7 +1,9 @@
 error TS5055: Cannot write file 'tests/cases/compiler/c.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/c.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.ts (0 errors) ====
     class c {
     }

tests/baselines/reference/jsFileCompilationOptionalParameter.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,13): error TS8009: '?' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     function F(p?) { }
                 ~

tests/baselines/reference/jsFileCompilationPublicMethodSyntaxOfClass.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(2,5): error TS8009: 'public' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     class C {
         public foo() {

tests/baselines/reference/jsFileCompilationPublicParameterModifier.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,23): error TS8012: 'parameter modifiers' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     class C { constructor(public x) { }}
                           ~~~~~~

tests/baselines/reference/jsFileCompilationReturnTypeSyntaxOfFunction.errors.txt

@@ -1,8 +1,10 @@
 error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 tests/cases/compiler/a.js(1,15): error TS8010: 'types' can only be used in a .ts file.
 
 
 !!! error TS5055: Cannot write file 'tests/cases/compiler/a.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig
 ==== tests/cases/compiler/a.js (1 errors) ====
     function F(): number { }
                   ~~~~~~