From bbd592cb6c449dd0b96b8e6a8103126d698f8262 Mon Sep 17 00:00:00 2001
From: Stephan Unverwerth <s.unverwerth@gmx.de>
Date: Mon, 13 Apr 2020 01:07:31 +0200
Subject: [PATCH] LibJS: Tweak FunctionPrototype::to_string and constructors

The output of FunctionPrototype::to_string is now more in line
with the output in Firefox. The builtin constructors have been
extended to include their function name in the output.
---
 Libraries/LibJS/Runtime/ArrayConstructor.cpp         | 1 +
 Libraries/LibJS/Runtime/BooleanConstructor.cpp       | 1 +
 Libraries/LibJS/Runtime/DateConstructor.cpp          | 1 +
 Libraries/LibJS/Runtime/ErrorConstructor.cpp         | 1 +
 Libraries/LibJS/Runtime/FunctionConstructor.cpp      | 1 +
 Libraries/LibJS/Runtime/FunctionPrototype.cpp        | 6 +++++-
 Libraries/LibJS/Runtime/NativeFunction.cpp           | 5 +++++
 Libraries/LibJS/Runtime/NativeFunction.h             | 1 +
 Libraries/LibJS/Runtime/NumberConstructor.cpp        | 1 +
 Libraries/LibJS/Runtime/ObjectConstructor.cpp        | 1 +
 Libraries/LibJS/Runtime/StringConstructor.cpp        | 1 +
 Libraries/LibJS/Tests/Function.prototype.toString.js | 4 ++--
 Libraries/LibJS/Tests/function-TypeError.js          | 2 +-
 13 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Libraries/LibJS/Runtime/ArrayConstructor.cpp b/Libraries/LibJS/Runtime/ArrayConstructor.cpp
index 6be1953fff..bfaaccd05f 100644
--- a/Libraries/LibJS/Runtime/ArrayConstructor.cpp
+++ b/Libraries/LibJS/Runtime/ArrayConstructor.cpp
@@ -34,6 +34,7 @@
 namespace JS {
 
 ArrayConstructor::ArrayConstructor()
+    : NativeFunction("Array")
 {
     put("prototype", interpreter().array_prototype());
     put("length", Value(1));
diff --git a/Libraries/LibJS/Runtime/BooleanConstructor.cpp b/Libraries/LibJS/Runtime/BooleanConstructor.cpp
index c8254abd66..3f5d54a68a 100644
--- a/Libraries/LibJS/Runtime/BooleanConstructor.cpp
+++ b/Libraries/LibJS/Runtime/BooleanConstructor.cpp
@@ -33,6 +33,7 @@
 namespace JS {
 
 BooleanConstructor::BooleanConstructor()
+    : NativeFunction("Boolean")
 {
     put("prototype", Value(interpreter().boolean_prototype()));
     put("length", Value(1));
diff --git a/Libraries/LibJS/Runtime/DateConstructor.cpp b/Libraries/LibJS/Runtime/DateConstructor.cpp
index 407c95d38d..9f825a6b96 100644
--- a/Libraries/LibJS/Runtime/DateConstructor.cpp
+++ b/Libraries/LibJS/Runtime/DateConstructor.cpp
@@ -34,6 +34,7 @@
 namespace JS {
 
 DateConstructor::DateConstructor()
+    : NativeFunction("Date")
 {
     put("prototype", interpreter().date_prototype());
     put("length", Value(7));
diff --git a/Libraries/LibJS/Runtime/ErrorConstructor.cpp b/Libraries/LibJS/Runtime/ErrorConstructor.cpp
index b62018fe02..082d3d3944 100644
--- a/Libraries/LibJS/Runtime/ErrorConstructor.cpp
+++ b/Libraries/LibJS/Runtime/ErrorConstructor.cpp
@@ -31,6 +31,7 @@
 namespace JS {
 
 ErrorConstructor::ErrorConstructor()
+    : NativeFunction("Error")
 {
     put("prototype", interpreter().error_prototype());
     put("length", Value(1));
diff --git a/Libraries/LibJS/Runtime/FunctionConstructor.cpp b/Libraries/LibJS/Runtime/FunctionConstructor.cpp
index 6a005f8324..fc93e3d13c 100644
--- a/Libraries/LibJS/Runtime/FunctionConstructor.cpp
+++ b/Libraries/LibJS/Runtime/FunctionConstructor.cpp
@@ -35,6 +35,7 @@
 namespace JS {
 
 FunctionConstructor::FunctionConstructor()
+    : NativeFunction("Function")
 {
     put("prototype", interpreter().function_prototype());
     put("length", Value(1));
diff --git a/Libraries/LibJS/Runtime/FunctionPrototype.cpp b/Libraries/LibJS/Runtime/FunctionPrototype.cpp
index 33f36335af..62e6c60068 100644
--- a/Libraries/LibJS/Runtime/FunctionPrototype.cpp
+++ b/Libraries/LibJS/Runtime/FunctionPrototype.cpp
@@ -122,7 +122,11 @@ Value FunctionPrototype::to_string(Interpreter& interpreter)
         // function_body = body.to_source();
         function_body = "  ???";
     }
-    auto function_source = String::format("function %s(%s) {\n%s\n}", function_name.characters(), function_parameters.characters(), function_body.characters());
+
+    auto function_source = String::format("function %s(%s) {\n%s\n}",
+        function_name.is_null() ? "" : function_name.characters(),
+        function_parameters.characters(),
+        function_body.characters());
     return js_string(interpreter, function_source);
 }
 
diff --git a/Libraries/LibJS/Runtime/NativeFunction.cpp b/Libraries/LibJS/Runtime/NativeFunction.cpp
index e50988105c..aadf7d8060 100644
--- a/Libraries/LibJS/Runtime/NativeFunction.cpp
+++ b/Libraries/LibJS/Runtime/NativeFunction.cpp
@@ -36,6 +36,11 @@ NativeFunction::NativeFunction(const FlyString& name, AK::Function<Value(Interpr
 {
 }
 
+NativeFunction::NativeFunction(const FlyString& name)
+    : m_name(name)
+{
+}
+
 NativeFunction::~NativeFunction()
 {
 }
diff --git a/Libraries/LibJS/Runtime/NativeFunction.h b/Libraries/LibJS/Runtime/NativeFunction.h
index 8495cb7cb8..d79fb38b04 100644
--- a/Libraries/LibJS/Runtime/NativeFunction.h
+++ b/Libraries/LibJS/Runtime/NativeFunction.h
@@ -43,6 +43,7 @@ public:
     virtual bool has_constructor() const { return false; }
 
 protected:
+    NativeFunction(const FlyString& name);
     NativeFunction() {}
 
 private:
diff --git a/Libraries/LibJS/Runtime/NumberConstructor.cpp b/Libraries/LibJS/Runtime/NumberConstructor.cpp
index 817a4858b0..4a5c9fc80c 100644
--- a/Libraries/LibJS/Runtime/NumberConstructor.cpp
+++ b/Libraries/LibJS/Runtime/NumberConstructor.cpp
@@ -37,6 +37,7 @@
 namespace JS {
 
 NumberConstructor::NumberConstructor()
+    : NativeFunction("Number")
 {
     put_native_function("isSafeInteger", is_safe_integer, 1);
 
diff --git a/Libraries/LibJS/Runtime/ObjectConstructor.cpp b/Libraries/LibJS/Runtime/ObjectConstructor.cpp
index ad00184707..21bd5c18b3 100644
--- a/Libraries/LibJS/Runtime/ObjectConstructor.cpp
+++ b/Libraries/LibJS/Runtime/ObjectConstructor.cpp
@@ -35,6 +35,7 @@
 namespace JS {
 
 ObjectConstructor::ObjectConstructor()
+    : NativeFunction("Object")
 {
     put("prototype", interpreter().object_prototype());
 
diff --git a/Libraries/LibJS/Runtime/StringConstructor.cpp b/Libraries/LibJS/Runtime/StringConstructor.cpp
index 5001e6ba8b..f28c89b307 100644
--- a/Libraries/LibJS/Runtime/StringConstructor.cpp
+++ b/Libraries/LibJS/Runtime/StringConstructor.cpp
@@ -33,6 +33,7 @@
 namespace JS {
 
 StringConstructor::StringConstructor()
+    : NativeFunction("String")
 {
     put("prototype", interpreter().string_prototype());
     put("length", Value(1));
diff --git a/Libraries/LibJS/Tests/Function.prototype.toString.js b/Libraries/LibJS/Tests/Function.prototype.toString.js
index 0d52bc7940..231a49458d 100644
--- a/Libraries/LibJS/Tests/Function.prototype.toString.js
+++ b/Libraries/LibJS/Tests/Function.prototype.toString.js
@@ -10,8 +10,8 @@ try {
         }
         return bar + 42;
     }).toString() === "function (foo, bar, baz) {\n  ???\n}");
-    assert(console.log.toString() === "function () {\n  [NativeFunction]\n}");
-    assert(Function.toString() === "function () {\n  [FunctionConstructor]\n}");
+    assert(console.log.toString() === "function log() {\n  [NativeFunction]\n}");
+    assert(Function.toString() === "function Function() {\n  [FunctionConstructor]\n}");
 
     console.log("PASS");
 } catch (e) {
diff --git a/Libraries/LibJS/Tests/function-TypeError.js b/Libraries/LibJS/Tests/function-TypeError.js
index 2909c802e3..2d411c2221 100644
--- a/Libraries/LibJS/Tests/function-TypeError.js
+++ b/Libraries/LibJS/Tests/function-TypeError.js
@@ -41,7 +41,7 @@ try {
         new isNaN();
     } catch(e) {
         assert(e.name === "TypeError");
-        assert(e.message === "function () {\n  [NativeFunction]\n} is not a constructor");
+        assert(e.message === "function isNaN() {\n  [NativeFunction]\n} is not a constructor");
     }
 
     console.log("PASS");