Add native windows launcher to replace the current .bat files. NFC (#24858)

This change does not start using the executable launcher by default.
That can happen later once we get more feedback on it. For example,
its not clear if this will lead to issues with virus/security scanners. 

Assuming we don't run into any issues I hope to eventually completely
remove support for the `.bat` files.

There are several reasons to want to do this:

1. Batch files are notoriously painful to work with and mis-understood.
2. Should be faster (no need to launch cmd.exe).
3. Works around several known issues with .bat files including one that
is known unsolvable one (see emcc.bat for more details)
4. In the future we could potentially launch clang directly, bypassing
the python completely (or at least only invoking python for the link
stage).

See: #26229
See: #19207

Author: sbc100

.circleci/config.yml

@@ -1249,6 +1249,30 @@ jobs:
     steps:
       - test-sockets-chrome
 
+  build-windows-launcher:
+    executor:
+      name: win/server-2022
+      shell: bash.exe -eo pipefail
+    steps:
+      - checkout
+      - run:
+          name: "build pylauncher"
+          shell: cmd.exe
+          command: .circleci\setup_vs2022.bat && cd tools\pylauncher && call build.bat
+      - store_artifacts:
+          path: tools/pylauncher/pylauncher.exe
+          destination: pylauncher.exe
+      - install-emsdk
+      - pip-install:
+          python: "$EMSDK_PYTHON"
+      - run:
+          name: "create_entry_points"
+          command: $EMSDK_PYTHON tools/maint/create_entry_points.py --exe-files
+      - run:
+          name: "crossplatform tests"
+          command: test/runner.exe core0.test_hello_world
+
+
   # windows and mac do not have separate build and test jobs, as they only run
   # a limited set of tests; it is simpler and faster to do it all in one job.
   test-windows:
@@ -1275,6 +1299,10 @@ jobs:
       EMTEST_BROWSER: "0"
     steps:
       - checkout
+      - run:
+          name: Build launcher
+          command: call .circleci\setup_vs2019.bat && cd tools\pylauncher && call build.bat
+          shell: cmd.exe
       - run:
           name: Install packages
           command: |
@@ -1284,9 +1312,6 @@ jobs:
       - install-emsdk
       - pip-install:
           python: "$EMSDK_PYTHON"
-      # run-tests depends on the ./test/runner script which is normally only
-      # created on UNIX systems (windows uses runner.bat)
-      - run: $EMSDK_PYTHON tools/maint/create_entry_points.py --all
       - run:
           name: "crossplatform tests"
           command: test/runner.bat --crossplatform-only
@@ -1391,6 +1416,7 @@ workflows:
       - test-node-compat
       - test-windows
       - test-windows-browser-firefox
+      - build-windows-launcher
       - test-mac-arm64:
           requires:
             - build-linux

.circleci/setup_vs2019.bat

@@ -0,0 +1,4 @@
+echo "setting up x64 toolchain"
+call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" x86_amd64
+where cl.exe
+echo "done"

.circleci/setup_vs2022.bat

@@ -0,0 +1,4 @@
+echo "setting up x64 toolchain"
+call "C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\vcvarsall.bat" x64
+where cl.exe
+echo "done"

.gitignore

@@ -39,6 +39,8 @@ coverage.xml
 !/tools/run_python.ps1
 !/tools/run_python_compiler.ps1
 
+/tools/maint/pylauncher/pylauncher.obj
+
 # Shell scripts (created by ./tools/maint/create_entry_points.py)
 em++
 emcc
@@ -88,3 +90,28 @@ emsymbolizer.bat
 test/runner.bat
 tools/file_packager.bat
 tools/webidl_binder.bat
+
+bootstrap.exe
+em++.exe
+emcc.exe
+em-config.exe
+emar.exe
+embuilder.exe
+emcmake.exe
+emconfigure.exe
+emdump.exe
+emdwp.exe
+emmake.exe
+emnm.exe
+empath-split.exe
+emprofile.exe
+emranlib.exe
+emrun.exe
+emscan-deps.exe
+emscons.exe
+emsize.exe
+emstrip.exe
+emsymbolizer.exe
+tools/file_packager.exe
+tools/webidl_binder.exe
+test/runner.exe

cmake/Modules/Platform/Emscripten.cmake

@@ -66,7 +66,13 @@ get_filename_component(EMSCRIPTEN_ROOT_PATH "${EMSCRIPTEN_ROOT_PATH}" ABSOLUTE)
 list(APPEND CMAKE_MODULE_PATH "${EMSCRIPTEN_ROOT_PATH}/cmake/Modules")
 
 if (CMAKE_HOST_WIN32)
-  set(EMCC_SUFFIX ".bat")
+  # We use windows executables these days rather than `.bat` files, but we
+  # still support a fallback of using `.bat` files.
+  if (EXISTS "${EMSCRIPTEN_ROOT_PATH}/emcc.exe")
+    set(EMCC_SUFFIX ".exe")
+  else()
+    set(EMCC_SUFFIX ".bat")
+  endif()
 else()
   set(EMCC_SUFFIX "")
 endif()

tools/maint/create_entry_points.py

@@ -14,6 +14,7 @@
 """
 
 import os
+import shutil
 import stat
 import sys
 
@@ -61,12 +62,20 @@
 }
 
 
+windows_exe = os.path.join(__rootdir__, 'tools/pylauncher/pylauncher.exe')
+
+
 def make_executable(filename):
   old_mode = stat.S_IMODE(os.stat(filename).st_mode)
   os.chmod(filename, old_mode | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)
 
 
-def main(all_platforms):
+def maybe_remove(filename):
+  if os.path.exists(filename):
+    os.remove(filename)
+
+
+def main(all_platforms, use_exe_files):
   is_windows = sys.platform.startswith('win')
   is_msys2 = 'MSYSTEM' in os.environ
   do_unix = all_platforms or not is_windows or is_msys2
@@ -99,15 +108,20 @@ def generate_entry_points(cmd, path):
         make_executable(launcher)
 
       if do_windows:
-        with open(launcher + '.bat', 'w') as f:
-          f.write(bat_data)
-
-        with open(launcher + '.ps1', 'w') as f:
-          f.write(ps1_data)
+        maybe_remove(launcher + '.bat')
+        maybe_remove(launcher + '.ps1')
+        maybe_remove(launcher + '.exe')
+        if use_exe_files:
+          shutil.copyfile(windows_exe, launcher + '.exe')
+        else:
+          with open(launcher + '.bat', 'w') as f:
+            f.write(bat_data)
+          with open(launcher + '.ps1', 'w') as f:
+            f.write(ps1_data)
 
   generate_entry_points(entry_points, os.path.join(__scriptdir__, 'run_python'))
   generate_entry_points(compiler_entry_points, os.path.join(__scriptdir__, 'run_python_compiler'))
 
 
 if __name__ == '__main__':
-  sys.exit(main('--all' in sys.argv))
+  sys.exit(main('--all' in sys.argv, '--exe-files' in sys.argv))

tools/pylauncher/README.md

@@ -0,0 +1,11 @@
+Windows Python Script Launcher
+==============================
+
+This directory contains a simple launcher program for windows which is used to
+execute the emscripten compiler entry points using the python interpreter.  It
+uses the its own name (the name of the currently running executable) to
+determine which python script to run and serves the same purpose as the
+``run_python.sh`` script does on non-windows platforms.
+
+We build this executable statically using ``/MT`` so that it is maximally
+portable.

tools/pylauncher/build.bat

@@ -0,0 +1,4 @@
+:: /MT :  Statically link to the C runtime library for max portability
+:: /O1 : Favor small code (optimization for size)
+
+cl pylauncher.c /Fe:pylauncher.exe /MT /O1

tools/pylauncher/build.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+SCRIPT_DIR=$(dirname "${BASH_SOURCE[0]}")
+cd ${SCRIPT_DIR}
+
+x86_64-w64-mingw32-gcc -Werror -static-libgcc -static-libstdc++ -s -Os pylauncher.c -o pylauncher.exe -lshlwapi -lshell32