fix: support Windows ARM64 (clangarm64) in install.cmd (#1259)

* fix: support Windows ARM64 (clangarm64) in install.cmd

Git for Windows on ARM64 uses a `clangarm64` directory instead of
`mingw64`. The installer now auto-detects `clangarm64` when
`mingw64` is not present, so it works out of the box on ARM64
Windows machines without requiring the user to manually supply
the path.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: remove trailing whitespace from install.cmd

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* fix: correctly resolve PREFIX when git.exe is under the arch dir in PATH

When 'where git.exe' resolves to ...\mingw64\bin\git.exe or
...\clangarm64\bin\git.exe, installdir becomes the architecture directory
itself. Detect that case by inspecting the leaf directory name instead of
appending mingw64/clangarm64 (which produced non-existent ...\mingw64\mingw64
paths) or using ..\ segments.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

install.cmd

@@ -39,13 +39,34 @@ goto :defaultpath
 rem remove the last slash
 SET bindir=%bindir:~0,-1%
 for %%G in ("%bindir%") do set installdir=%%~dpG
-set PREFIX=%installdir%mingw64
+rem strip a trailing slash so we can inspect the leaf directory name
+if "%installdir:~-1%"=="\" set installdir=%installdir:~0,-1%
+rem git.exe found under <GitRoot>\mingw64\bin or <GitRoot>\clangarm64\bin
+rem means installdir already is the architecture directory itself
+for %%G in ("%installdir%") do set archdir=%%~nxG
+if /I "%archdir%"=="mingw64" (
+    set PREFIX=%installdir%
+) else if /I "%archdir%"=="clangarm64" (
+    set PREFIX=%installdir%
+) else if exist "%installdir%\mingw64" (
+    set PREFIX=%installdir%\mingw64
+) else if exist "%installdir%\clangarm64" (
+    set PREFIX=%installdir%\clangarm64
+) else (
+    set PREFIX=%installdir%\mingw64
+)
 goto :foundprefix
 
 :defaultpath
 :: default for Git for Windows 2.x
 if exist "%ProgramFiles%\Git" (
-    set PREFIX=%ProgramFiles%\Git\mingw64
+    if exist "%ProgramFiles%\Git\mingw64" (
+        set PREFIX=%ProgramFiles%\Git\mingw64
+    ) else if exist "%ProgramFiles%\Git\clangarm64" (
+        set PREFIX=%ProgramFiles%\Git\clangarm64
+    ) else (
+        set PREFIX=%ProgramFiles%\Git\mingw64
+    )
 )
 
 :foundprefix
@@ -55,9 +76,11 @@ IF NOT "%~1"=="" (
     REM just supplying the git dir is enough...
     if exist "%~1\mingw64" (
         set PREFIX=%~1\mingw64
+    ) else if exist "%~1\clangarm64" (
+        set PREFIX=%~1\clangarm64
     ) else (
         echo Using git install path "%~1" as PREFIX, please make sure it's really a
-        echo path to the mingw64 directory...
+        echo path to the mingw64 or clangarm64 directory...
         echo.
         SET PREFIX=%~1
     )
@@ -72,12 +95,14 @@ set GIT_INSTALL_DIR=!GIT_INSTALL_DIR:"=!
 IF %GIT_INSTALL_DIR:~-1%==\ SET GIT_INSTALL_DIR=%GIT_INSTALL_DIR:~0,-1%
 
 if not exist "%GIT_INSTALL_DIR%\mingw64" (
-    echo No mingw64 folder found in %GIT_INSTALL_DIR%.
-    echo.
-    echo Please supply a proper "Git for Windows 2.x" install path:
-    echo "install.cmd c:\[git-install-path]"
-    set ERROR=1
-    goto :exit
+    if not exist "%GIT_INSTALL_DIR%\clangarm64" (
+        echo No mingw64 or clangarm64 folder found in %GIT_INSTALL_DIR%.
+        echo.
+        echo Please supply a proper "Git for Windows 2.x" install path:
+        echo "install.cmd c:\[git-install-path]"
+        set ERROR=1
+        goto :exit
+    )
 )
 
 echo Installing to %PREFIX%
@@ -116,7 +141,7 @@ FOR /R "%GITEXTRAS%\bin" %%i in (*.*) DO (
     TYPE "%GITEXTRAS%\helper\reset-env" >> "%PREFIX%\bin\%%~ni"
     TYPE "%GITEXTRAS%\helper\git-extra-utility" >> "%PREFIX%\bin\%%~ni"
     TYPE "%GITEXTRAS%\helper\is-git-repo" >> "%PREFIX%\bin\%%~ni"
-    
+
     REM Added /E option for installation fix on Windows 10.0.17134 and higher
     MORE /E +2 "%GITEXTRAS%\bin\%%~ni" >> "%PREFIX%\bin\%%~ni"
 )
@@ -127,7 +152,7 @@ FOR %%i in (%COMMANDS_WITHOUT_REPO%) DO (
     ECHO #^^!/usr/bin/env bash > "%PREFIX%\bin\%%i"
     TYPE "%GITEXTRAS%\helper\reset-env" >> "%PREFIX%\bin\%%i"
     TYPE "%GITEXTRAS%\helper\git-extra-utility" >> "%PREFIX%\bin\%%i"
-    
+
     REM Added /E option for installation fix on Windows 10.0.17134 and higher
     MORE /E +2 "%GITEXTRAS%\bin\%%i" >> "%PREFIX%\bin\%%i"
 )