better recovery

Author: Andarist

src/compiler/parser.ts

@@ -7505,7 +7505,11 @@ namespace Parser {
             case SyntaxKind.LetKeyword:
             case SyntaxKind.ConstKeyword:
             case SyntaxKind.UsingKeyword:
+                return parseVariableStatement(pos, hasJSDoc, modifiersIn);
             case SyntaxKind.AwaitKeyword:
+                if (!isAwaitUsingDeclaration()) {
+                    break;
+                }
                 return parseVariableStatement(pos, hasJSDoc, modifiersIn);
             case SyntaxKind.FunctionKeyword:
                 return parseFunctionDeclaration(pos, hasJSDoc, modifiersIn);
@@ -7534,17 +7538,16 @@ namespace Parser {
                     default:
                         return parseExportDeclaration(pos, hasJSDoc, modifiersIn);
                 }
-            default:
-                if (modifiersIn) {
-                    // We reached this point because we encountered decorators and/or modifiers and assumed a declaration
-                    // would follow. For recovery and error reporting purposes, return an incomplete declaration.
-                    const missing = createMissingNode<MissingDeclaration>(SyntaxKind.MissingDeclaration, /*reportAtCurrentPosition*/ true, Diagnostics.Declaration_expected);
-                    setTextRangePos(missing, pos);
-                    (missing as Mutable<MissingDeclaration>).modifiers = modifiersIn;
-                    return missing;
-                }
-                return undefined!; // TODO: GH#18217
         }
+        if (modifiersIn) {
+            // We reached this point because we encountered decorators and/or modifiers and assumed a declaration
+            // would follow. For recovery and error reporting purposes, return an incomplete declaration.
+            const missing = createMissingNode<MissingDeclaration>(SyntaxKind.MissingDeclaration, /*reportAtCurrentPosition*/ true, Diagnostics.Declaration_expected);
+            setTextRangePos(missing, pos);
+            (missing as Mutable<MissingDeclaration>).modifiers = modifiersIn;
+            return missing;
+        }
+        return undefined!; // TODO: GH#18217
     }
 
     function nextTokenIsStringLiteral() {

tests/baselines/reference/decoratorOnAwait.errors.txt

@@ -1,11 +1,11 @@
-decoratorOnAwait.ts(4,7): error TS1134: Variable declaration expected.
+decoratorOnAwait.ts(3,5): error TS1146: Declaration expected.
 
 
 ==== decoratorOnAwait.ts (1 errors) ====
     declare function dec<T>(target: T): T;
 
     @dec
+        
+!!! error TS1146: Declaration expected.
     await 1
-          ~
-!!! error TS1134: Variable declaration expected.
 

tests/baselines/reference/decoratorOnAwait.js

@@ -8,5 +8,4 @@ await 1
 
 
 //// [decoratorOnAwait.js]
-var ;
-1;
+await 1;

tests/baselines/reference/decoratorOnAwait.types

@@ -12,6 +12,8 @@ declare function dec<T>(target: T): T;
 >    : ^ ^^      ^^ ^^^^^ 
 
 await 1
+>await 1 : 1
+>        : ^
 >1 : 1
 >  : ^
 

tests/baselines/reference/decoratorOnUsing.errors.txt

@@ -0,0 +1,14 @@
+decoratorOnUsing.ts(4,7): error TS1134: Variable declaration expected.
+
+
+==== decoratorOnUsing.ts (1 errors) ====
+    declare function dec<T>(target: T): T;
+    
+    @dec
+    using 1
+          ~
+!!! error TS1134: Variable declaration expected.
+    
+    @dec
+    using x
+    

tests/baselines/reference/decoratorOnUsing.js

@@ -0,0 +1,16 @@
+//// [tests/cases/conformance/decorators/invalid/decoratorOnUsing.ts] ////
+
+//// [decoratorOnUsing.ts]
+declare function dec<T>(target: T): T;
+
+@dec
+using 1
+
+@dec
+using x
+
+
+//// [decoratorOnUsing.js]
+using ;
+1;
+using x;

tests/baselines/reference/decoratorOnUsing.symbols

@@ -0,0 +1,21 @@
+//// [tests/cases/conformance/decorators/invalid/decoratorOnUsing.ts] ////
+
+=== decoratorOnUsing.ts ===
+declare function dec<T>(target: T): T;
+>dec : Symbol(dec, Decl(decoratorOnUsing.ts, 0, 0))
+>T : Symbol(T, Decl(decoratorOnUsing.ts, 0, 21))
+>target : Symbol(target, Decl(decoratorOnUsing.ts, 0, 24))
+>T : Symbol(T, Decl(decoratorOnUsing.ts, 0, 21))
+>T : Symbol(T, Decl(decoratorOnUsing.ts, 0, 21))
+
+@dec
+>dec : Symbol(dec, Decl(decoratorOnUsing.ts, 0, 0))
+
+using 1
+
+@dec
+>dec : Symbol(dec, Decl(decoratorOnUsing.ts, 0, 0))
+
+using x
+>x : Symbol(x, Decl(decoratorOnUsing.ts, 6, 5))
+

tests/baselines/reference/decoratorOnUsing.types

@@ -0,0 +1,25 @@
+//// [tests/cases/conformance/decorators/invalid/decoratorOnUsing.ts] ////
+
+=== decoratorOnUsing.ts ===
+declare function dec<T>(target: T): T;
+>dec : <T>(target: T) => T
+>    : ^ ^^      ^^ ^^^^^ 
+>target : T
+>       : ^
+
+@dec
+>dec : <T>(target: T) => T
+>    : ^ ^^      ^^ ^^^^^ 
+
+using 1
+>1 : 1
+>  : ^
+
+@dec
+>dec : <T>(target: T) => T
+>    : ^ ^^      ^^ ^^^^^ 
+
+using x
+>x : any
+>  : ^^^
+

tests/cases/conformance/decorators/invalid/decoratorOnUsing.ts

@@ -0,0 +1,8 @@
+// @target: esnext
+declare function dec<T>(target: T): T;
+
+@dec
+using 1
+
+@dec
+using x