add support for const type parameter

Summary: Adds support for [`const` modifier on type parameters](microsoft/TypeScript#51865). E.g. ``` function foo<const T>(x: T): [T] {...} ``` We parse an optional `const` keyword right before parsing the variance of a type parameter. ``` cd ~/fbsource/xplat/hermes/unsupported/tools/rustgen buck run //xplat/hermes/unsupported/tools/rustgen:rustgen -- ffi > ../../juno/crates/hermes/src/parser/generated_ffi.rs buck run //xplat/hermes/unsupported/tools/rustgen:rustgen -- cvt > ../../juno/crates/juno/src/hparser/generated_cvt.rs ``` Reviewed By: avp Differential Revision: D66739150 fbshipit-source-id: 66411ee424cea3ab19a1f8c2ab09d80abdf2737a
facebook · Dec 18, 2024 · 3a24531 · 3a24531
1 parent 468be6b
commit 3a24531
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Showing 8 changed files with 123 additions and 5 deletions.
diff --git a/include/hermes/AST/ESTree.def b/include/hermes/AST/ESTree.def
@@ -1109,14 +1109,16 @@ ESTREE_NODE_1_ARGS(
 ESTREE_NODE_1_ARGS(
     TypeParameterDeclaration, Flow,
     NodeList, params, false)
-ESTREE_NODE_5_ARGS(
+ESTREE_NODE_6_ARGS(
     TypeParameter, Flow,
     NodeLabel, name, false,
+    NodeBoolean, const, false,
     NodePtr, bound, true,
     NodePtr, variance, true,
     NodePtr, default, true,
     NodeBoolean, usesExtendsBound, false)
 ESTREE_IGNORE_IF_EMPTY(TypeParameter, usesExtendsBound)
+ESTREE_IGNORE_IF_EMPTY(TypeParameter, const)
 ESTREE_NODE_1_ARGS(
     TypeParameterInstantiation, Flow,
     NodeList, params, false)

diff --git a/lib/Parser/JSParserImpl-flow.cpp b/lib/Parser/JSParserImpl-flow.cpp
@@ -2894,7 +2894,7 @@ Optional<ESTree::Node *> JSParserImpl::parsePrimaryTypeAnnotationFlow() {
                 start,
                 getPrevTokenEndLoc(),
                 new (context_) ESTree::TypeParameterNode(
-                    name, bound, nullptr, nullptr, true))));
+                    name, false, bound, nullptr, nullptr, true))));
       }
 
       {
@@ -3938,8 +3938,8 @@ Optional<ESTree::Node *> JSParserImpl::parseTypeMappedTypePropertyFlow(
   ESTree::Node *keyTparam = setLocation(
       left,
       left,
-      new (context_)
-          ESTree::TypeParameterNode(id, nullptr, nullptr, nullptr, false));
+      new (context_) ESTree::TypeParameterNode(
+          id, false, nullptr, nullptr, nullptr, false));
 
   auto optSourceType = parseTypeAnnotationFlow();
   if (!optSourceType)
@@ -4098,7 +4098,12 @@ Optional<ESTree::Node *> JSParserImpl::parseTypeParamsFlow() {
 
 Optional<ESTree::Node *> JSParserImpl::parseTypeParamFlow() {
   SMLoc start = tok_->getStartLoc();
+  bool isConst = false;
   ESTree::Node *variance = nullptr;
+  if (check(TokenKind::rw_const)) {
+    isConst = true;
+    advance(JSLexer::GrammarContext::Type);
+  }
 
   if (check(TokenKind::plus, TokenKind::minus)) {
     variance = setLocation(
@@ -4149,7 +4154,7 @@ Optional<ESTree::Node *> JSParserImpl::parseTypeParamFlow() {
       start,
       getPrevTokenEndLoc(),
       new (context_) ESTree::TypeParameterNode(
-          name, bound, variance, initializer, usesExtendsBound));
+          name, isConst, bound, variance, initializer, usesExtendsBound));
 }
 
 Optional<ESTree::Node *> JSParserImpl::parseTypeArgsFlow() {

diff --git a/test/Parser/flow/const-type-param-error1.js b/test/Parser/flow/const-type-param-error1.js
@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -parse-flow -dump-ast -pretty-json %s 2>&1) | %FileCheck %s --match-full-lines
+
+function foo<const>() {}
+// CHECK: {{.*}}:10:19: error: 'identifier' expected in type parameter
diff --git a/test/Parser/flow/const-type-param-error2.js b/test/Parser/flow/const-type-param-error2.js
@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -parse-flow -dump-ast -pretty-json %s 2>&1) | %FileCheck %s --match-full-lines
+
+function foo<const + const>() {}
+// CHECK: {{.*}}:10:22: error: 'identifier' expected in type parameter
diff --git a/test/Parser/flow/function-typeparams.js b/test/Parser/flow/function-typeparams.js
@@ -100,6 +100,81 @@ function foo<T>(x: number): number {}
 // CHECK-NEXT:         "async": false
 // CHECK-NEXT:       },
 // CHECK-NEXT:       "directive": null
+// CHECK-NEXT:     },
+
+(function<const T>(): void {});
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "type": "ExpressionStatement",
+// CHECK-NEXT:       "expression": {
+// CHECK-NEXT:         "type": "FunctionExpression",
+// CHECK-NEXT:         "id": null,
+// CHECK-NEXT:         "params": [],
+// CHECK-NEXT:         "body": {
+// CHECK-NEXT:           "type": "BlockStatement",
+// CHECK-NEXT:           "body": []
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "typeParameters": {
+// CHECK-NEXT:           "type": "TypeParameterDeclaration",
+// CHECK-NEXT:           "params": [
+// CHECK-NEXT:             {
+// CHECK-NEXT:               "type": "TypeParameter",
+// CHECK-NEXT:               "name": "T",
+// CHECK-NEXT:               "const": true,
+// CHECK-NEXT:               "bound": null,
+// CHECK-NEXT:               "variance": null,
+// CHECK-NEXT:               "default": null
+// CHECK-NEXT:             }
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "returnType": {
+// CHECK-NEXT:           "type": "TypeAnnotation",
+// CHECK-NEXT:           "typeAnnotation": {
+// CHECK-NEXT:             "type": "VoidTypeAnnotation"
+// CHECK-NEXT:           }
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "generator": false,
+// CHECK-NEXT:         "async": false
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "directive": null
+// CHECK-NEXT:     },
+
+(function<const +T>(): void {});
+// CHECK-NEXT:     {
+// CHECK-NEXT:       "type": "ExpressionStatement",
+// CHECK-NEXT:       "expression": {
+// CHECK-NEXT:         "type": "FunctionExpression",
+// CHECK-NEXT:         "id": null,
+// CHECK-NEXT:         "params": [],
+// CHECK-NEXT:         "body": {
+// CHECK-NEXT:           "type": "BlockStatement",
+// CHECK-NEXT:           "body": []
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "typeParameters": {
+// CHECK-NEXT:           "type": "TypeParameterDeclaration",
+// CHECK-NEXT:           "params": [
+// CHECK-NEXT:             {
+// CHECK-NEXT:               "type": "TypeParameter",
+// CHECK-NEXT:               "name": "T",
+// CHECK-NEXT:               "const": true,
+// CHECK-NEXT:               "bound": null,
+// CHECK-NEXT:               "variance": {
+// CHECK-NEXT:                 "type": "Variance",
+// CHECK-NEXT:                 "kind": "plus"
+// CHECK-NEXT:               },
+// CHECK-NEXT:               "default": null
+// CHECK-NEXT:             }
+// CHECK-NEXT:           ]
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "returnType": {
+// CHECK-NEXT:           "type": "TypeAnnotation",
+// CHECK-NEXT:           "typeAnnotation": {
+// CHECK-NEXT:             "type": "VoidTypeAnnotation"
+// CHECK-NEXT:           }
+// CHECK-NEXT:         },
+// CHECK-NEXT:         "generator": false,
+// CHECK-NEXT:         "async": false
+// CHECK-NEXT:       },
+// CHECK-NEXT:       "directive": null
 // CHECK-NEXT:     }
 
 // CHECK-NEXT:   ]

diff --git a/test/Parser/flow/type-param-error-const-name.js b/test/Parser/flow/type-param-error-const-name.js
@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: (! %hermesc -parse-flow -dump-ast -pretty-json %s 2>&1) | %FileCheck %s --match-full-lines
+
+function foo<const>() {}
+// CHECK: {{.*}}:10:19: error: 'identifier' expected in type parameter
diff --git a/unsupported/juno/crates/hermes/src/parser/generated_ffi.rs b/unsupported/juno/crates/hermes/src/parser/generated_ffi.rs
@@ -882,6 +882,7 @@ extern "C" {
     pub fn hermes_get_TypeParameterDeclaration_params(node: NodePtr) -> NodeListRef;
     // TypeParameter
     pub fn hermes_get_TypeParameter_name(node: NodePtr) -> NodeLabel;
+    pub fn hermes_get_TypeParameter_const(node: NodePtr) -> bool;
     pub fn hermes_get_TypeParameter_bound(node: NodePtr) -> NodePtrOpt;
     pub fn hermes_get_TypeParameter_variance(node: NodePtr) -> NodePtrOpt;
     pub fn hermes_get_TypeParameter_default(node: NodePtr) -> NodePtrOpt;

diff --git a/unsupported/juno/crates/juno/src/hparser/generated_cvt.rs b/unsupported/juno/crates/juno/src/hparser/generated_cvt.rs
@@ -2172,13 +2172,15 @@ pub unsafe fn cvt_node_ptr<'parser, 'gc>(
         }
         NodeKind::TypeParameter => {
           let name = cvt.cvt_label(gc, hermes_get_TypeParameter_name(n));
+          let const = hermes_get_TypeParameter_const(n);
           let bound = cvt_node_ptr_opt(cvt, gc, hermes_get_TypeParameter_bound(n));
           let variance = cvt_node_ptr_opt(cvt, gc, hermes_get_TypeParameter_variance(n));
           let default = cvt_node_ptr_opt(cvt, gc, hermes_get_TypeParameter_default(n));
           let uses_extends_bound = hermes_get_TypeParameter_usesExtendsBound(n);
           let mut template = ast::template::TypeParameter {
               metadata: ast::TemplateMetadata {range, ..Default::default()},
                   name,
+                  const,
                   bound,
                   variance,
                   default,