ToolRelauncher

A simple command line tool that can be used as a wrapper for your other tools to launch the most recent built configuration of your tool. (How many times do you need to say the word "tool" before it loses all meaning?)

E.g. you might have a config validator that you launch from VSCode and from your server, and you want most people to run the optimized build configuration called "Development", but still allow programmers to easily run the "Debug" build when they want to. Instead of teaching both VSCode and your server how to pick the correct build configuration (e.g. via a config or looking which was most recently built), you can just build Relauncher and name it ConfigValidator.exe, and have both VSCode and the server run ConfigValidator.exe. Relauncher will then look for ConfigValidatorDebug.exe, ConfigValidatorDevelopment.exe, and ConfigValidatorShipping.exe, and pick the most recently modified version of these options -- forwarding all the arguments.

The goal of ToolRelauncher is to be simple and small, so as to add as little overhead as possible (both in build times and launch times).

Setup

1. Build RelauncherMain.cpp
2. Name it after the tool you want it to relaunch (either by having the compiler output that name, or by copying Relauncher.exe to the appropriate name)
3. Point your scripts & tools at the base tool name without a build configuration

Windows

Here's a stripped down command line to build ToolRelauncher on Windows with a static CRT:

"C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\Llvm\x64\bin\clang++.exe" RelauncherMain.cpp -g -Wall -Wextra -Werror -O2 -DNDEBUG -DUNICODE -D_UNICODE -o Relauncher.exe

You can add -D_MT -D_DLL "-Wl,/nodefaultlib:libcmt" -lmsvcrt -lvcruntime -lucrt to the command line to link against a dynamic CRT.

It should also build with cl.exe without any specific options needed.

Linux

Here's a stripped down command line to build ToolRelauncher on Linux:

clang++-12 RelauncherMain.cpp -g -Wall -Wextra -Werror -o Relauncher

Assumptions

Relauncher assumes your tools are named after the build configuration, rather than put in a different folder based on it. It also assumes Unreal-esque build configurations of Debug, Development, and Shipping (because that's what we use).

Pull requests that extend ToolRelauncher to support other setups are welcome.

Compatibility

ToolRelauncher has only been tested with clang 12 on Windows (from Visual Studio's package) and Linux, and with both unicode and non-unicode Windows build options.

Command line arguments

Relauncher supports two command line arguments, which must be the first argument(s):

• --debug-relauncher: Print some debug output to help understand what Relauncher considered when making its decision
• --which-relauncher: Print the name of the executable that would be launched to stdout and then exit, and do not launch the target exe