From aa52fdba598ce3add23cf5ed0f32393f51925c54 Mon Sep 17 00:00:00 2001
From: Jan Melcher <mail@jan-melcher.de>
Date: Wed, 4 Aug 2021 10:09:33 +0200
Subject: [PATCH] BREAKING: Disallow "true", "false", and "null" as enum values

The specification disallows these in the SDL grammar definition, and using one of these enum values would result in a schema that would throw validation errors on creation.

Fixes #3221.
---
 src/language/__tests__/parser-test.ts        |  7 +++++
 src/language/__tests__/schema-parser-test.ts |  6 ++++-
 src/language/ast.ts                          |  2 +-
 src/language/parser.ts                       | 27 +++++++++++++++++---
 4 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/src/language/__tests__/parser-test.ts b/src/language/__tests__/parser-test.ts
index ffdfe11b461..534f76fb348 100644
--- a/src/language/__tests__/parser-test.ts
+++ b/src/language/__tests__/parser-test.ts
@@ -120,6 +120,13 @@ describe('Parser', () => {
     });
   });
 
+  it('does not allow "true" as enum value', () => {
+    expectSyntaxError('enum Test { VALID, true }').to.deep.equal({
+      message: 'Syntax Error: Name "true" is not a valid enum value.',
+      locations: [{ line: 1, column: 20 }],
+    });
+  });
+
   it('parses multi-byte characters', () => {
     // Note: \u0A0A could be naively interpreted as two line-feed chars.
     const ast = parse(`
diff --git a/src/language/__tests__/schema-parser-test.ts b/src/language/__tests__/schema-parser-test.ts
index e596bba35dc..78fb429454a 100644
--- a/src/language/__tests__/schema-parser-test.ts
+++ b/src/language/__tests__/schema-parser-test.ts
@@ -52,7 +52,11 @@ function fieldNodeWithArgs(
 function enumValueNode(name: unknown, loc: unknown) {
   return {
     kind: 'EnumValueDefinition',
-    name: nameNode(name, loc),
+    name: {
+      kind: 'EnumValue',
+      value: name,
+      loc,
+    },
     description: undefined,
     directives: [],
     loc,
diff --git a/src/language/ast.ts b/src/language/ast.ts
index ccb6240111a..0429c569a8c 100644
--- a/src/language/ast.ts
+++ b/src/language/ast.ts
@@ -584,7 +584,7 @@ export interface EnumValueDefinitionNode {
   readonly kind: 'EnumValueDefinition';
   readonly loc?: Location;
   readonly description?: StringValueNode;
-  readonly name: NameNode;
+  readonly name: EnumValueNode;
   readonly directives?: ReadonlyArray<ConstDirectiveNode>;
 }
 
diff --git a/src/language/parser.ts b/src/language/parser.ts
index 7095cad1d11..d93cb14a1f2 100644
--- a/src/language/parser.ts
+++ b/src/language/parser.ts
@@ -1036,13 +1036,11 @@ export class Parser {
 
   /**
    * EnumValueDefinition : Description? EnumValue Directives[Const]?
-   *
-   * EnumValue : Name
    */
   parseEnumValueDefinition(): EnumValueDefinitionNode {
     const start = this._lexer.token;
     const description = this.parseDescription();
-    const name = this.parseName();
+    const name = this.parseEnumValue();
     const directives = this.parseConstDirectives();
     return this.node<EnumValueDefinitionNode>(start, {
       kind: Kind.ENUM_VALUE_DEFINITION,
@@ -1052,6 +1050,29 @@ export class Parser {
     });
   }
 
+  /**
+   * EnumValue : Name but not `true`, `false` or `null`
+   */
+  parseEnumValue(): EnumValueNode {
+    const node = this.parseName();
+    if (
+      node.value === 'true' ||
+      node.value === 'false' ||
+      node.value === 'null'
+    ) {
+      throw syntaxError(
+        this._lexer.source,
+        this._lexer.lastToken.start,
+        `${getTokenDesc(this._lexer.lastToken)} is not a valid enum value.`,
+      );
+    }
+    return {
+      kind: 'EnumValue',
+      value: node.value,
+      loc: node.loc,
+    };
+  }
+
   /**
    * InputObjectTypeDefinition :
    *   - Description? input Name Directives[Const]? InputFieldsDefinition?