add spelling suggestion support for module import

Author: Kingwl

src/compiler/checker.ts

@@ -1852,7 +1852,15 @@ namespace ts {
                         combineValueAndTypeSymbols(symbolFromVariable, symbolFromModule) :
                         symbolFromModule || symbolFromVariable;
                     if (!symbol) {
-                        error(name, Diagnostics.Module_0_has_no_exported_member_1, getFullyQualifiedName(moduleSymbol), declarationNameToString(name));
+                        const moduleName = getFullyQualifiedName(moduleSymbol);
+                        const declarationName = declarationNameToString(name);
+                        const suggestion = getSuggestionForNonexistentModule(name, targetSymbol);
+                        if (suggestion !== undefined) {
+                            error(name, Diagnostics.Module_0_has_no_exported_member_1_Did_you_mean_2, moduleName, declarationName, suggestion);
+                        }
+                        else {
+                            error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName);
+                        }
                     }
                     return symbol;
                 }
@@ -16188,6 +16196,11 @@ namespace ts {
             return result && symbolName(result);
         }
 
+        function getSuggestionForNonexistentModule(name: Identifier, targetModule: Symbol): string | undefined {
+            const suggestion = targetModule.exports && getSpellingSuggestionForName(idText(name), getExportsOfModuleAsArray(targetModule), SymbolFlags.ModuleMember);
+            return suggestion && symbolName(suggestion);
+        }
+
         /**
          * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough.
          * Names less than length 3 only check for case-insensitive equality, not levenshtein distance.

src/compiler/diagnosticMessages.json

@@ -2317,6 +2317,10 @@
         "category": "Error",
         "code": 2723
     },
+    "Module '{0}' has no exported member '{1}'. Did you mean '{2}'?": {
+        "category": "Error",
+        "code": 2724
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000

tests/baselines/reference/exportSpellingSuggestion.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/conformance/es6/modules/b.ts(1,10): error TS2724: Module '"tests/cases/conformance/es6/modules/a"' has no exported member 'assertNevar'. Did you mean 'assertNever'?
+
+
+==== tests/cases/conformance/es6/modules/a.ts (0 errors) ====
+    export function assertNever(x: never, msg: string) {
+        throw new Error("Unexpected " + msg);
+    }
+    
+==== tests/cases/conformance/es6/modules/b.ts (1 errors) ====
+    import { assertNevar } from "./a";
+             ~~~~~~~~~~~
+!!! error TS2724: Module '"tests/cases/conformance/es6/modules/a"' has no exported member 'assertNevar'. Did you mean 'assertNever'?
+    

tests/baselines/reference/exportSpellingSuggestion.js

@@ -0,0 +1,21 @@
+//// [tests/cases/conformance/es6/modules/exportSpellingSuggestion.ts] ////
+
+//// [a.ts]
+export function assertNever(x: never, msg: string) {
+    throw new Error("Unexpected " + msg);
+}
+
+//// [b.ts]
+import { assertNevar } from "./a";
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+function assertNever(x, msg) {
+    throw new Error("Unexpected " + msg);
+}
+exports.assertNever = assertNever;
+//// [b.js]
+"use strict";
+exports.__esModule = true;

tests/baselines/reference/exportSpellingSuggestion.symbols

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/es6/modules/a.ts ===
+export function assertNever(x: never, msg: string) {
+>assertNever : Symbol(assertNever, Decl(a.ts, 0, 0))
+>x : Symbol(x, Decl(a.ts, 0, 28))
+>msg : Symbol(msg, Decl(a.ts, 0, 37))
+
+    throw new Error("Unexpected " + msg);
+>Error : Symbol(Error, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>msg : Symbol(msg, Decl(a.ts, 0, 37))
+}
+
+=== tests/cases/conformance/es6/modules/b.ts ===
+import { assertNevar } from "./a";
+>assertNevar : Symbol(assertNevar, Decl(b.ts, 0, 8))
+

tests/baselines/reference/exportSpellingSuggestion.types

@@ -0,0 +1,18 @@
+=== tests/cases/conformance/es6/modules/a.ts ===
+export function assertNever(x: never, msg: string) {
+>assertNever : (x: never, msg: string) => void
+>x : never
+>msg : string
+
+    throw new Error("Unexpected " + msg);
+>new Error("Unexpected " + msg) : Error
+>Error : ErrorConstructor
+>"Unexpected " + msg : string
+>"Unexpected " : "Unexpected "
+>msg : string
+}
+
+=== tests/cases/conformance/es6/modules/b.ts ===
+import { assertNevar } from "./a";
+>assertNevar : any
+

tests/cases/conformance/es6/modules/exportSpellingSuggestion.ts

@@ -0,0 +1,7 @@
+// @filename: a.ts
+export function assertNever(x: never, msg: string) {
+    throw new Error("Unexpected " + msg);
+}
+
+// @filename: b.ts
+import { assertNevar } from "./a";