improve error message TS2307

Author: Philipp Zins

src/compiler/checker.ts

@@ -2007,7 +2007,7 @@ namespace ts {
         }
 
         function resolveExternalModuleName(location: Node, moduleReferenceExpression: Expression): Symbol {
-            return resolveExternalModuleNameWorker(location, moduleReferenceExpression, Diagnostics.Cannot_find_module_0);
+            return resolveExternalModuleNameWorker(location, moduleReferenceExpression, Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module);
         }
 
         function resolveExternalModuleNameWorker(location: Node, moduleReferenceExpression: Expression, moduleNotFoundError: DiagnosticMessage, isForAugmentation = false): Symbol {

src/compiler/diagnosticMessages.json

@@ -976,7 +976,7 @@
         "category": "Error",
         "code": 2306
     },
-    "Cannot find module '{0}'.": {
+    "Cannot find module '{0}' or cannot find corresponding type declarations for this module.": {
         "category": "Error",
         "code": 2307
     },

src/harness/unittests/tscWatchMode.ts

@@ -183,7 +183,7 @@ namespace ts.tscWatch {
 
     function getDiagnosticModuleNotFoundOfFile(program: Program, file: FileOrFolder, moduleName: string) {
         const quotedModuleName = `"${moduleName}"`;
-        return getDiagnosticOfFileFromProgram(program, file.path, file.content.indexOf(quotedModuleName), quotedModuleName.length, Diagnostics.Cannot_find_module_0, moduleName);
+        return getDiagnosticOfFileFromProgram(program, file.path, file.content.indexOf(quotedModuleName), quotedModuleName.length, Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module, moduleName);
     }
 
     describe("tsc-watch program updates", () => {

src/harness/unittests/tsserverProjectSystem.ts

@@ -3629,7 +3629,7 @@ namespace ts.projectSystem {
             host.runQueuedTimeoutCallbacks();
             diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
             verifyDiagnostics(diags, [
-                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
+                { diagnosticMessage: Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module, errorTextArguments: ["./moduleFile"] }
             ]);
             assert.equal(diags.length, 1);
 
@@ -3680,7 +3680,7 @@ namespace ts.projectSystem {
             host.runQueuedTimeoutCallbacks();
             diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
             verifyDiagnostics(diags, [
-                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
+                { diagnosticMessage: Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module, errorTextArguments: ["./moduleFile"] }
             ]);
 
             moduleFile.path = moduleFileOldPath;
@@ -3755,7 +3755,7 @@ namespace ts.projectSystem {
             );
             let diags = session.executeCommand(getErrRequest).response as server.protocol.Diagnostic[];
             verifyDiagnostics(diags, [
-                { diagnosticMessage: Diagnostics.Cannot_find_module_0, errorTextArguments: ["./moduleFile"] }
+                { diagnosticMessage: Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module, errorTextArguments: ["./moduleFile"] }
             ]);
 
             host.reloadFS([file1, moduleFile]);
@@ -3808,7 +3808,7 @@ namespace ts.projectSystem {
             session.clearMessages();
 
             host.runQueuedImmediateCallbacks();
-            const moduleNotFound = Diagnostics.Cannot_find_module_0;
+            const moduleNotFound = Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module;
             const startOffset = file1.content.indexOf('"') + 1;
             checkErrorMessage(session, "semanticDiag", {
                 file: file1.path, diagnostics: [{
@@ -5598,7 +5598,7 @@ namespace ts.projectSystem {
             let diags = project.getLanguageService().getSemanticDiagnostics(root.path);
             assert.equal(diags.length, 1);
             const diag = diags[0];
-            assert.equal(diag.code, Diagnostics.Cannot_find_module_0.code);
+            assert.equal(diag.code, Diagnostics.Cannot_find_module_0_or_cannot_find_corresponding_type_declarations_for_this_module.code);
             assert.equal(flattenDiagnosticMessageText(diag.messageText, "\n"), "Cannot find module 'bar'.");
             callsTrackingHost.verifyCalledOn(CalledMapsWithSingleArg.fileExists, imported.path);