From 4f87c26575d378c4e7d77c516a5a4471c31183ac Mon Sep 17 00:00:00 2001
From: Nick Gerleman <ngerlem@microsoft.com>
Date: Mon, 9 Mar 2020 12:48:50 -0700
Subject: [PATCH] [Cherry-Pick] Fix Support For SystraceSection (#4267)

* Fix Support For SysTraceSection

Addresses #4245, During deforking work I left a build logic typo which caused SysTraceSection to noop. When trying to reenable in deforked React Native, we end up having a compile error since stock Facebook code will pass doubles as an arg to SysTraceSection, and we will internally only accept string.

This was fixed in microsof/react-native by commenting out the SysTraceSection call that passed a double. A real solution is to allow our implementation of FbSystraceSection to accept non-string args and convert to strings, as Facebook's seemingly does.

- Use type traits to call std::to_string on args not convertible to string
- Move functions to be private instead of public

Still need a plan to validate this.

* Simplify things a bit

* Solely rely on is_convertible

Constructable was sort of wrong before, because we're actually doing assignment, but even then we likely only want things that allow implicit conversions.
---
 ...e-windows-2020-03-07-06-25-07-fix-etw.json |  9 ++++
 vnext/PropertySheets/React.Cpp.props          |  2 +-
 vnext/ReactWindowsCore/tracing/fbsystrace.h   | 47 ++++++++-----------
 3 files changed, 30 insertions(+), 28 deletions(-)
 create mode 100644 change/react-native-windows-2020-03-07-06-25-07-fix-etw.json

diff --git a/change/react-native-windows-2020-03-07-06-25-07-fix-etw.json b/change/react-native-windows-2020-03-07-06-25-07-fix-etw.json
new file mode 100644
index 00000000000..64de1786ac4
--- /dev/null
+++ b/change/react-native-windows-2020-03-07-06-25-07-fix-etw.json
@@ -0,0 +1,9 @@
+{
+  "type": "prerelease",
+  "comment": "Fix Support For SysTraceSection",
+  "packageName": "react-native-windows",
+  "email": "ngerlem@microsoft.com",
+  "commit": "6745910fa922e880c314c9581419a6a2cc3f2e2a",
+  "dependentChangeType": "patch",
+  "date": "2020-03-07T14:25:07.210Z"
+}
\ No newline at end of file
diff --git a/vnext/PropertySheets/React.Cpp.props b/vnext/PropertySheets/React.Cpp.props
index d07ebeb0c4b..7c4e4eb932b 100644
--- a/vnext/PropertySheets/React.Cpp.props
+++ b/vnext/PropertySheets/React.Cpp.props
@@ -41,7 +41,7 @@
   <ItemDefinitionGroup>
     <ClCompile>
       <PreprocessorDefinitions Condition="'$(ENABLE_ETW_TRACING)'=='true'">ENABLE_ETW_TRACING;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <PreprocessorDefinitions Condition="'$(ENABLE_JS_SYSTRACE_TO_ETW)'=='true' AND '$PATCH_RN'=='true'">ENABLE_JS_SYSTRACE_TO_ETW;WITH_FBSYSTRACE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions Condition="'$(ENABLE_JS_SYSTRACE_TO_ETW)'=='true'">ENABLE_JS_SYSTRACE_TO_ETW;WITH_FBSYSTRACE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
   </ItemDefinitionGroup>
 
diff --git a/vnext/ReactWindowsCore/tracing/fbsystrace.h b/vnext/ReactWindowsCore/tracing/fbsystrace.h
index 256ea90d209..edaaaa123ff 100644
--- a/vnext/ReactWindowsCore/tracing/fbsystrace.h
+++ b/vnext/ReactWindowsCore/tracing/fbsystrace.h
@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
 #pragma once
 
 #include <stdint.h>
@@ -6,6 +9,7 @@
 #include <chrono>
 #include <mutex>
 #include <string>
+#include <type_traits>
 #include <unordered_map>
 
 #define TRACE_TAG_REACT_CXX_BRIDGE 1 << 10
@@ -51,44 +55,33 @@ class FbSystraceSection {
             .count());
   }
 
-  void init(std::string &&v) {
-    args_[index_++] = std::move(v);
-    begin_section();
+  template <typename... RestArg>
+  FbSystraceSection(uint64_t tag, std::string &&profileName, RestArg &&... rest)
+      : tag_(tag), profile_name_(std::move(profileName)) {
+    id_ = s_id_counter++;
+    init(std::forward<RestArg>(rest)...);
   }
 
-  void init(const std::string &v) {
-    args_[index_++] = v; // copy
-    begin_section();
+  ~FbSystraceSection() {
+    end_section();
   }
 
+ private:
   void init() {
     begin_section();
   }
 
-  template <typename... ConvertsToStringPiece>
-  void init(std::string &&v, ConvertsToStringPiece &&... rest) {
-    args_[index_++] = std::move(v);
-    init(std::forward<ConvertsToStringPiece>(rest)...);
-  }
-
-  template <typename... ConvertsToStringPiece>
-  void init(const std::string &v, ConvertsToStringPiece &&... rest) {
-    args_[index_++] = v; // copy
-    init(std::forward<ConvertsToStringPiece>(rest)...);
-  }
-
-  template <typename... ConvertsToStringPiece>
-  FbSystraceSection(uint64_t tag, std::string &&v, ConvertsToStringPiece &&... rest)
-      : tag_(tag), profile_name_(std::move(v)) {
-    id_ = s_id_counter++;
-    init(std::forward<ConvertsToStringPiece>(rest)...);
-  }
+  template <typename Arg, typename... RestArg>
+  void init(Arg &&arg, RestArg &&... rest) {
+    if constexpr (std::is_convertible_v<Arg, std::string>) {
+      args_[index_++] = std::forward<Arg>(arg);
+    } else {
+      args_[index_++] = std::to_string(std::forward<Arg>(arg));
+    }
 
-  ~FbSystraceSection() {
-    end_section();
+    init(std::forward<RestArg>(rest)...);
   }
 
- private:
   std::array<std::string, SYSTRACE_SECTION_MAX_ARGS> args_;
   uint64_t tag_{0};