Allow arbitrary catch clause type annotations

Author: jakebailey

src/compiler/checker.ts

@@ -10206,11 +10206,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
         // Use type from type annotation if one is present
         const declaredType = tryGetTypeFromEffectiveTypeNode(declaration);
-        if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) {
-            if (declaredType) {
-                // If the catch clause is explicitly annotated with any or unknown, accept it, otherwise error.
-                return isTypeAny(declaredType) || declaredType === unknownType ? declaredType : errorType;
-            }
+        if (!declaredType && isCatchClauseVariableDeclarationOrBindingElement(declaration)) {
             // If the catch clause is not explicitly annotated, treat it as though it were explicitly
             // annotated with unknown or any, depending on useUnknownInCatchVariables.
             return useUnknownInCatchVariables ? unknownType : anyType;
@@ -41179,14 +41175,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             if (catchClause.variableDeclaration) {
                 const declaration = catchClause.variableDeclaration;
                 checkVariableLikeDeclaration(declaration);
-                const typeNode = getEffectiveTypeAnnotationNode(declaration);
-                if (typeNode) {
-                    const type = getTypeFromTypeNode(typeNode);
-                    if (type && !(type.flags & TypeFlags.AnyOrUnknown)) {
-                        grammarErrorOnFirstToken(typeNode, Diagnostics.Catch_clause_variable_type_annotation_must_be_any_or_unknown_if_specified);
-                    }
-                }
-                else if (declaration.initializer) {
+                if (declaration.initializer) {
                     grammarErrorOnFirstToken(declaration.initializer, Diagnostics.Catch_clause_variable_cannot_have_an_initializer);
                 }
                 else {

src/compiler/diagnosticMessages.json

@@ -607,10 +607,6 @@
         "category": "Error",
         "code": 1195
     },
-    "Catch clause variable type annotation must be 'any' or 'unknown' if specified.": {
-        "category": "Error",
-        "code": 1196
-    },
     "Catch clause variable cannot have an initializer.": {
         "category": "Error",
         "code": 1197

tests/baselines/reference/catchClauseWithTypeAnnotation.errors.txt

@@ -1,16 +1,15 @@
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(17,36): error TS2339: Property 'foo' does not exist on type 'unknown'.
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(18,37): error TS2339: Property 'foo' does not exist on type 'unknown'.
-tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(19,23): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
-tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(20,23): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(25,23): error TS2339: Property 'toLowerCase' does not exist on type 'number'.
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(29,29): error TS2492: Cannot redeclare identifier 'x' in catch clause.
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(30,29): error TS2403: Subsequent variable declarations must have the same type.  Variable 'x' must be of type 'boolean', but here has type 'string'.
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(36,22): error TS2339: Property 'x' does not exist on type '{}'.
 tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(37,22): error TS2339: Property 'x' does not exist on type '{}'.
-tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(38,27): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
-tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(39,27): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(38,22): error TS2339: Property 'x' does not exist on type '{}'.
+tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts(39,22): error TS2339: Property 'x' does not exist on type 'Error'.
 
 
-==== tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts (10 errors) ====
+==== tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.ts (9 errors) ====
     type any1 = any;
     type unknown1 = unknown;
 
@@ -34,16 +33,14 @@ tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.t
                                         ~~~
 !!! error TS2339: Property 'foo' does not exist on type 'unknown'.
         try { } catch (x: Error) { } // error in the type
-                          ~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
         try { } catch (x: object) { } // error in the type
-                          ~~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
 
         try { console.log(); }
         // @ts-ignore
         catch (e: number) { // e should not be a `number`
             console.log(e.toLowerCase());
+                          ~~~~~~~~~~~
+!!! error TS2339: Property 'toLowerCase' does not exist on type 'number'.
         }
 
         // minor bug: shows that the `catch` argument is skipped when checking scope
@@ -66,10 +63,10 @@ tests/cases/conformance/statements/tryStatements/catchClauseWithTypeAnnotation.t
                          ~
 !!! error TS2339: Property 'x' does not exist on type '{}'.
         try { } catch ({ x }: object) { } // error in the type
-                              ~~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+                         ~
+!!! error TS2339: Property 'x' does not exist on type '{}'.
         try { } catch ({ x }: Error) { } // error in the type
-                              ~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+                         ~
+!!! error TS2339: Property 'x' does not exist on type 'Error'.
     }
 

tests/baselines/reference/catchClauseWithTypeAnnotation.types

@@ -72,10 +72,10 @@ function fn(x: boolean) {
 >foo : any
 
     try { } catch (x: Error) { } // error in the type
->x : any
+>x : Error
 
     try { } catch (x: object) { } // error in the type
->x : any
+>x : object
 
     try { console.log(); }
 >console.log() : void
@@ -85,7 +85,7 @@ function fn(x: boolean) {
 
     // @ts-ignore
     catch (e: number) { // e should not be a `number`
->e : any
+>e : number
 
         console.log(e.toLowerCase());
 >console.log(e.toLowerCase()) : void
@@ -94,7 +94,7 @@ function fn(x: boolean) {
 >log : (...data: any[]) => void
 >e.toLowerCase() : any
 >e.toLowerCase : any
->e : any
+>e : number
 >toLowerCase : any
     }
 

tests/baselines/reference/jsdocCatchClauseWithTypeAnnotation.errors.txt

@@ -1,15 +1,14 @@
 tests/cases/conformance/jsdoc/foo.js(20,54): error TS2339: Property 'foo' does not exist on type 'unknown'.
 tests/cases/conformance/jsdoc/foo.js(21,54): error TS2339: Property 'foo' does not exist on type 'unknown'.
-tests/cases/conformance/jsdoc/foo.js(22,31): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
-tests/cases/conformance/jsdoc/foo.js(23,31): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+tests/cases/conformance/jsdoc/foo.js(28,25): error TS2339: Property 'toLowerCase' does not exist on type 'number'.
 tests/cases/conformance/jsdoc/foo.js(35,7): error TS2492: Cannot redeclare identifier 'err' in catch clause.
 tests/cases/conformance/jsdoc/foo.js(46,45): error TS2339: Property 'x' does not exist on type '{}'.
 tests/cases/conformance/jsdoc/foo.js(47,45): error TS2339: Property 'x' does not exist on type '{}'.
-tests/cases/conformance/jsdoc/foo.js(48,31): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
-tests/cases/conformance/jsdoc/foo.js(49,31): error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+tests/cases/conformance/jsdoc/foo.js(48,43): error TS2339: Property 'x' does not exist on type 'Error'.
+tests/cases/conformance/jsdoc/foo.js(49,44): error TS2339: Property 'x' does not exist on type '{}'.
 
 
-==== tests/cases/conformance/jsdoc/foo.js (9 errors) ====
+==== tests/cases/conformance/jsdoc/foo.js (8 errors) ====
     /**
      * @typedef {any} Any
      */
@@ -36,16 +35,14 @@ tests/cases/conformance/jsdoc/foo.js(49,31): error TS1196: Catch clause variable
                                                          ~~~
 !!! error TS2339: Property 'foo' does not exist on type 'unknown'.
         try { } catch (/** @type {Error} */ err) { }                     // error in the type
-                                  ~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
         try { } catch (/** @type {object} */ err) { }                    // error in the type
-                                  ~~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
 
         try { console.log(); }
         // @ts-ignore
         catch (/** @type {number} */ err) { // e should not be a `number`
             console.log(err.toLowerCase());
+                            ~~~~~~~~~~~
+!!! error TS2339: Property 'toLowerCase' does not exist on type 'number'.
         }
 
     	// minor bug: shows that the `catch` argument is skipped when checking scope
@@ -72,10 +69,10 @@ tests/cases/conformance/jsdoc/foo.js(49,31): error TS1196: Catch clause variable
                                                 ~
 !!! error TS2339: Property 'x' does not exist on type '{}'.
         try { } catch (/** @type {Error} */ { x }) { }                   // error in the type
-                                  ~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+                                              ~
+!!! error TS2339: Property 'x' does not exist on type 'Error'.
         try { } catch (/** @type {object} */ { x }) { }                  // error in the type
-                                  ~~~~~~
-!!! error TS1196: Catch clause variable type annotation must be 'any' or 'unknown' if specified.
+                                               ~
+!!! error TS2339: Property 'x' does not exist on type '{}'.
     }
 

tests/baselines/reference/jsdocCatchClauseWithTypeAnnotation.types

@@ -72,10 +72,10 @@ function fn() {
 >foo : any
 
     try { } catch (/** @type {Error} */ err) { }                     // error in the type
->err : any
+>err : Error
 
     try { } catch (/** @type {object} */ err) { }                    // error in the type
->err : any
+>err : object
 
     try { console.log(); }
 >console.log() : void
@@ -85,7 +85,7 @@ function fn() {
 
     // @ts-ignore
     catch (/** @type {number} */ err) { // e should not be a `number`
->err : any
+>err : number
 
         console.log(err.toLowerCase());
 >console.log(err.toLowerCase()) : void
@@ -94,7 +94,7 @@ function fn() {
 >log : (...data: any[]) => void
 >err.toLowerCase() : any
 >err.toLowerCase : any
->err : any
+>err : number
 >toLowerCase : any
     }
 

tests/baselines/reference/parserCatchClauseWithTypeAnnotation1.errors.txt

@@ -1,6 +1,6 @@
 === tests/cases/conformance/parser/ecmascript5/CatchClauses/parserCatchClauseWithTypeAnnotation1.ts ===
 try {
 } catch (e: Error) {
->e : any
+>e : Error
 }