install: use reg add to avoid setx truncating Windows PATH

INSTALL.bat and UNINSTALL.bat persist the system-wide PATH with
'setx /M', which silently truncates the value it writes to 1024
characters. When installing from a shell with an already long
inherited PATH, such as a Visual Studio Developer Prompt, this drops
the tail of the persisted PATH, which can remove entries required to
even start cmd.exe or powershell.exe in a later session. Use 'reg
add' on the same registry key instead, which has no such limit and
requires the same administrator privilege setx already needed.

Mark these Windows batch scripts, which intentionally carry
carriage-return line endings, with the cr-at-eol whitespace attribute
so the pre-commit hook stops flagging their line endings as trailing
whitespace.

Extend the native-cmd CI job to replace the inherited PATH with a
controlled value past the legacy 1024-character limit before
installing, then check the persisted registry PATH afterward, so a
regression here gets caught automatically. The replacement keeps the
length controlled and safely under the 8191-character command line
length limit of cmd.exe, rather than extending the runner's own
already large inherited PATH and risking hitting that separate limit.

Fixes #654

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Xavier Delaruelle <xavier.delaruelle@cea.fr>

Author: xdelaruelle

.gitattributes

@@ -23,3 +23,7 @@ script/pre-commit export-ignore
 # Scorecard entirely
 # no export of website-specific content
 doc/talk export-ignore
+# these Windows batch scripts intentionally use CRLF line endings, do not
+# flag the CR as a trailing whitespace error
+script/INSTALL.bat whitespace=cr-at-eol
+script/UNINSTALL.bat whitespace=cr-at-eol

.github/workflows/windows_tests.yaml

@@ -48,7 +48,31 @@ jobs:
         run: |
           jar xvf %DIST_WIN%.zip
           cd %DIST_WIN%
-          INSTALL.bat
+          :: replace (rather than extend) the inherited PATH with a
+          :: controlled value that is still past the legacy 1024-character
+          :: limit of the 'setx' tool previously used here, to simulate a
+          :: large pre-existing PATH such as found in a Visual Studio
+          :: Developer Prompt (see GH-654), while staying safely under the
+          :: 8191-character command line length limit of cmd.exe
+          setlocal enabledelayedexpansion
+          set "PATH=%SYSTEMROOT%\system32;%SYSTEMROOT%"
+          for /L %%i in (1,1,50) do set "PATH=!PATH!;C:\dummy-path-segment-%%i"
+          set "PATH=!PATH!;C:\marker-end-of-long-path"
+          call INSTALL.bat
+      - name: Check persisted PATH is not truncated
+        shell: cmd
+        run: |
+          reg query "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v PATH > persisted-path.txt
+          %SYSTEMROOT%\system32\find /i "marker-end-of-long-path" persisted-path.txt >nul
+          if errorlevel 1 (
+              echo "persisted system PATH truncated: marker entry not found"
+              exit /b 1
+          )
+          %SYSTEMROOT%\system32\find /i "%MODULE_DIR%" persisted-path.txt >nul
+          if errorlevel 1 (
+              echo "installation 'bin' directory not found in persisted system PATH"
+              exit /b 1
+          )
       - name: Test Modules installation
         shell: cmd
         run: |

.hunspell.en.dic

@@ -736,6 +736,7 @@ setState
 setenv
 setgid
 setq
+setx
 severities
 sexualized
 sgr

NEWS.rst

@@ -173,6 +173,12 @@ Modules 5.7.0 (not yet released)
   white matte color instead of black.
 * Doc: document Windows Terminal profile setup as an alternative way to
   initialize Modules on Windows without an install script. (fix issue #634)
+* Install: use ``reg add`` instead of ``setx /M`` to persist the system-wide
+  ``PATH`` environment variable in :file:`INSTALL.bat` and
+  :file:`UNINSTALL.bat`, as ``setx`` silently truncates the value it writes
+  to 1024 characters, which could corrupt the system ``PATH`` when installing
+  from a shell with an already long inherited ``PATH`` (e.g. a Visual Studio
+  Developer Prompt). (fix issue #654)
 
 
 .. _5.6 release notes:

doc/source/devel/ci.rst

@@ -107,7 +107,10 @@ on Windows:
     <https://www.bawt.tcl3d.org/>`_), built via ``make dist-win`` and
     installed/tested/uninstalled through the generated
     :file:`INSTALL.bat`/:file:`TESTINSTALL.bat`/:file:`UNINSTALL.bat`
-    scripts, driven from a ``cmd`` shell.
+    scripts, driven from a ``cmd`` shell. Before installing, the inherited
+    ``PATH`` is padded past the legacy 1024-character limit of the
+    ``setx`` tool (mimicking a Visual Studio Developer Prompt) to guard
+    against the persisted system ``PATH`` getting silently truncated.
 ``native-pwsh``
     Same native Windows install, but through the PowerShell variant
     (:file:`INSTALL_PWSH.bat`/:file:`TESTINSTALL_PWSH.ps1`).

script/INSTALL.bat

@@ -23,7 +23,9 @@ set FIND=%SYSTEMROOT%\system32\find
 echo %PATH% | %FIND% /i "%binpath:"=%">nul || set "NEWPATH=%binpath%;%PATH%"
 if not "%NEWPATH%" == "" (
    set "PATH=%NEWPATH%"
-   setx /M PATH "%NEWPATH%"
+   :: 'reg add' is used instead of 'setx /M' as the latter silently
+   :: truncates the value it persists to 1024 characters
+   reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v PATH /t REG_EXPAND_SZ /d "%NEWPATH%" /f
 )
 if errorlevel 1 ( exit /b 3 )
 

script/UNINSTALL.bat

@@ -13,7 +13,9 @@ setlocal enableextensions enabledelayedexpansion
 set "NEWPATH=!PATH:%binpath%;=!"
 if not "%NEWPATH%" == "%PATH%" (
    set "PATH=%NEWPATH%"
-   setx /M PATH "%NEWPATH%"
+   :: 'reg add' is used instead of 'setx /M' as the latter silently
+   :: truncates the value it persists to 1024 characters
+   reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v PATH /t REG_EXPAND_SZ /d "%NEWPATH%" /f
 )
 if errorlevel 1 ( exit /b 1 )