Simplified error recovery by just using 'parseTryStatement'.

Author: DanielRosenwasser

src/compiler/diagnosticInformationMap.generated.ts

@@ -160,8 +160,6 @@ module ts {
         Constructor_implementation_expected: { code: 2240, category: DiagnosticCategory.Error, key: "Constructor implementation expected." },
         An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements: { code: 2245, category: DiagnosticCategory.Error, key: "An export assignment cannot be used in a module with other exported elements." },
         A_parameter_property_is_only_allowed_in_a_constructor_implementation: { code: 2246, category: DiagnosticCategory.Error, key: "A parameter property is only allowed in a constructor implementation." },
-        A_catch_clause_must_be_preceded_by_a_try_statement: { code: 2249, category: DiagnosticCategory.Error, key: "A 'catch' clause must be preceded by a 'try' statement." },
-        A_finally_block_must_be_preceded_by_a_try_statement: { code: 2250, category: DiagnosticCategory.Error, key: "A 'finally' block must be preceded by a 'try' statement." },
         Circular_definition_of_import_alias_0: { code: 3000, category: DiagnosticCategory.Error, key: "Circular definition of import alias '{0}'." },
         Cannot_find_name_0: { code: 3001, category: DiagnosticCategory.Error, key: "Cannot find name '{0}'." },
         Module_0_has_no_exported_member_1: { code: 3002, category: DiagnosticCategory.Error, key: "Module '{0}' has no exported member '{1}'." },

src/compiler/diagnosticMessages.json

@@ -632,14 +632,6 @@
         "category": "Error",
         "code": 2246
     },
-    "A 'catch' clause must be preceded by a 'try' statement.": {
-        "category": "Error",
-        "code": 2249
-    },
-    "A 'finally' block must be preceded by a 'try' statement.": {
-        "category": "Error",
-        "code": 2250
-    },
 
     "Circular definition of import alias '{0}'.": {
         "category": "Error",
@@ -1246,4 +1238,4 @@
         "category": "Error",
         "code": -9999999
     }
-}
+}

src/compiler/parser.ts

@@ -2542,35 +2542,6 @@ module ts {
             return finishNode(node);
         }
 
-        // This function is used for parsing 'catch'/'finally' blocks
-        // in spite of them missing a 'try' statement.
-        function parseCatchOrFinallyBlocksMissingTryStatement(): TryStatement {
-
-            Debug.assert(token === SyntaxKind.CatchKeyword || token === SyntaxKind.FinallyKeyword,
-                "'parseCatchOrFinallyBlocksMissingTryStatement' should only be called when the current token is a 'catch' or 'finally' keyword.");
-
-            // We're just going to return a bogus TryStatement.
-            var node = <TryStatement>createNode(SyntaxKind.TryStatement);
-            node.tryBlock = <Block>createNode(SyntaxKind.Block);
-            node.tryBlock.statements = createMissingList<Statement>();
-
-            if (token === SyntaxKind.CatchKeyword) {
-                error(Diagnostics.A_catch_clause_must_be_preceded_by_a_try_statement);
-                node.catchBlock = parseCatchBlock();
-            }
-
-            if (token === SyntaxKind.FinallyKeyword) {
-                // Only report an error on the 'finally' block if we haven't on the 'catch' block.
-                if (node.catchBlock === undefined) {
-                    error(Diagnostics.A_finally_block_must_be_preceded_by_a_try_statement);
-                }
-
-                node.finallyBlock = parseTokenAndBlock(SyntaxKind.FinallyKeyword, SyntaxKind.FinallyBlock);
-            }
-
-            return finishNode(node);
-        }
-
         function parseTokenAndBlock(token: SyntaxKind, kind: SyntaxKind): Block {
             var pos = getNodePos();
             parseExpected(token);
@@ -2733,10 +2704,10 @@ module ts {
                 case SyntaxKind.ThrowKeyword:
                     return parseThrowStatement();
                 case SyntaxKind.TryKeyword:
-                    return parseTryStatement();
+                // Include the next two for error recovery.
                 case SyntaxKind.CatchKeyword:
                 case SyntaxKind.FinallyKeyword:
-                    return parseCatchOrFinallyBlocksMissingTryStatement();
+                    return parseTryStatement();
                 case SyntaxKind.DebuggerKeyword:
                     return parseDebuggerStatement();
                 default:

tests/baselines/reference/invalidTryStatements2.errors.txt

@@ -8,18 +8,18 @@
 
         catch(x) { } // error missing try
         ~~~~~
-!!! A 'catch' clause must be preceded by a 'try' statement.
+!!! 'try' expected.
 
         finally{ } // potential error; can be absorbed by the 'catch'
     }
 
     function fn2() {
         finally { } // error missing try
         ~~~~~~~
-!!! A 'finally' block must be preceded by a 'try' statement.
+!!! 'try' expected.
         catch (x) { } // error missing try
         ~~~~~
-!!! A 'catch' clause must be preceded by a 'try' statement.
+!!! 'try' expected.
 
         // no error
         try {
@@ -30,12 +30,12 @@
         // error missing try
         finally {
         ~~~~~~~
-!!! A 'finally' block must be preceded by a 'try' statement.
+!!! 'try' expected.
         }
 
         // error missing try
         catch (x) {
         ~~~~~
-!!! A 'catch' clause must be preceded by a 'try' statement.
+!!! 'try' expected.
         }
     }