From 4895d166450e2affed31281265a06947c1820d39 Mon Sep 17 00:00:00 2001
From: Klaus Meinhardt <klaus.meinhardt1@gmail.com>
Date: Sat, 28 Oct 2017 20:06:33 +0200
Subject: [PATCH] convertToObject: handle negative numbers in JSON

Fixes: #19551
---
 src/compiler/commandLineParser.ts              |  7 +++++++
 .../convertCompilerOptionsFromJson.ts          | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index f050c4a5d16..b7003fbffd9 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1138,6 +1138,13 @@ namespace ts {
                     reportInvalidOptionValue(option && option.type !== "number");
                     return Number((<NumericLiteral>valueExpression).text);
 
+                case SyntaxKind.PrefixUnaryExpression:
+                    if ((<PrefixUnaryExpression>valueExpression).operator !== SyntaxKind.MinusToken || (<PrefixUnaryExpression>valueExpression).operand.kind !== SyntaxKind.NumericLiteral) {
+                        break; // not valid JSON syntax
+                    }
+                    reportInvalidOptionValue(option && option.type !== "number");
+                    return -Number((<NumericLiteral>(<PrefixUnaryExpression>valueExpression).operand).text);
+
                 case SyntaxKind.ObjectLiteralExpression:
                     reportInvalidOptionValue(option && option.type !== "object");
                     const objectLiteralExpression = <ObjectLiteralExpression>valueExpression;
diff --git a/src/harness/unittests/convertCompilerOptionsFromJson.ts b/src/harness/unittests/convertCompilerOptionsFromJson.ts
index c55dee26dc4..09659762288 100644
--- a/src/harness/unittests/convertCompilerOptionsFromJson.ts
+++ b/src/harness/unittests/convertCompilerOptionsFromJson.ts
@@ -421,6 +421,24 @@ namespace ts {
             );
         });
 
+        it("Convert negative numbers in tsconfig.json ", () => {
+            assertCompilerOptions(
+                {
+                    "compilerOptions": {
+                        "allowJs": true,
+                        "maxNodeModuleJsDepth": -1
+                    }
+                }, "tsconfig.json",
+                {
+                    compilerOptions: {
+                        allowJs: true,
+                        maxNodeModuleJsDepth: -1
+                    },
+                    errors: []
+                }
+            );
+        });
+
         // jsconfig.json
         it("Convert correctly format jsconfig.json to compiler-options ", () => {
             assertCompilerOptions(