fix(openssl/windows): run vcvars in a CHILD cmd — it terminates its caller

Three runs in a row ended the same way, and the CRLF change did not move it:

  [bat] vspath=C:\Program Files\Microsoft Visual Studio\18\Enterprise
  ** Visual Studio 2026 Developer Command Prompt v18.8.2
  [vcvarsall.bat] Environment initialized for: 'x64'
  <nothing>

vcvars SUCCEEDS and then the script is gone: no further echo, no RESULT, exit 0.
Visual Studio's developer-prompt script terminates the batch that calls it, so
no amount of error handling after the `call` can ever run — the previous commit
blamed line endings, and this run disproves that (it ran with CRLF and behaved
identically).

The fix is structural rather than another guess at how vcvars exits: the build
moves into a second script invoked as `cmd /c <inner.bat>`. vcvars can then only
take that CHILD process down, while the outer script survives to record
RESULT=%errorlevel%. The vcvars path travels by environment variable instead of
as an argument, because a child cmd inherits the environment and that avoids
another layer of quoting around a path containing spaces.

The inner script keeps the same exit codes (13 vcvars, 14 cd, 20/21/22
Configure/nmake/install_sw) and the same per-step logging, so the next failure —
if there is one — still names itself.

Author: Sunrisepeak

pkgs/c/compat.openssl.lua

@@ -412,6 +412,7 @@ local function _install_windows_impl()
     os.mkdir(prefix)
     local logf = path.join(prefix, "mcpp_openssl_build.log")
     local bat  = path.join(prefix, "mcpp_openssl_build.bat")
+    local inner = path.join(prefix, "mcpp_openssl_inner.bat")
 
     local function note(msg)
         local fh = io.open(logf, "a")
@@ -474,34 +475,57 @@ local function _install_windows_impl()
     -- script that "succeeds" having done nothing after the first call.
     local logw  = tostring(logf):gsub("/", "\\")
     local prefw = tostring(prefix):gsub("/", "\\")
-    io.writefile(bat, table.concat({
+    local innerw = tostring(inner):gsub("/", "\\")
+    io.writefile(inner, table.concat({
         "@echo off",
-        'echo [bat] started >> "' .. logw .. '" 2>&1',
-        'set "VSWHERE=%ProgramFiles(x86)%\\Microsoft Visual Studio\\Installer\\vswhere.exe"',
-        'echo [bat] vswhere=%VSWHERE% >> "' .. logw .. '" 2>&1',
-        'if not exist "%VSWHERE%" ( echo [bat] RESULT=10 vswhere missing >> "' .. logw .. '" & exit /b 0 )',
-        'for /f "usebackq tokens=*" %%i in (`"%VSWHERE%" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath`) do set "VSPATH=%%i"',
-        'echo [bat] vspath=%VSPATH% >> "' .. logw .. '" 2>&1',
-        'if not defined VSPATH ( echo [bat] RESULT=11 no VC toolset >> "' .. logw .. '" & exit /b 0 )',
-        'set "VCVARS=%VSPATH%\\VC\\Auxiliary\\Build\\vcvars64.bat"',
-        'if not exist "%VCVARS%" ( echo [bat] RESULT=12 no vcvars64 >> "' .. logw .. '" & exit /b 0 )',
-        'call "%VCVARS%" >> "' .. logw .. '" 2>&1',
-        'if errorlevel 1 ( echo [bat] RESULT=13 vcvars failed >> "' .. logw .. '" & exit /b 0 )',
+        -- vcvars runs HERE, in a child cmd, so whatever it does to its caller
+        -- cannot reach the outer script.
+        'call "%MCPP_VCVARS%" >> "' .. logw .. '" 2>&1',
+        'if errorlevel 1 exit /b 13',
         'echo [bat] toolset ready >> "' .. logw .. '" 2>&1',
         'cd /d "' .. srcroot .. '"',
-        'if errorlevel 1 ( echo [bat] RESULT=14 cd failed >> "' .. logw .. '" & exit /b 0 )',
+        'if errorlevel 1 exit /b 14',
         'where perl >> "' .. logw .. '" 2>&1',
         'where nmake >> "' .. logw .. '" 2>&1',
         'echo [bat] configuring >> "' .. logw .. '" 2>&1',
         'perl Configure VC-WIN64A no-shared no-tests no-apps no-engine no-dso --prefix="' .. prefw .. '" --openssldir="' .. prefw .. '\\ssl" >> "' .. logw .. '" 2>&1',
-        'if errorlevel 1 ( echo [bat] RESULT=20 Configure failed >> "' .. logw .. '" & exit /b 0 )',
+        'if errorlevel 1 exit /b 20',
         'echo [bat] building >> "' .. logw .. '" 2>&1',
         'nmake >> "' .. logw .. '" 2>&1',
-        'if errorlevel 1 ( echo [bat] RESULT=21 nmake failed >> "' .. logw .. '" & exit /b 0 )',
+        'if errorlevel 1 exit /b 21',
         'echo [bat] installing >> "' .. logw .. '" 2>&1',
         'nmake install_sw >> "' .. logw .. '" 2>&1',
-        'if errorlevel 1 ( echo [bat] RESULT=22 nmake install_sw failed >> "' .. logw .. '" & exit /b 0 )',
-        'echo [bat] RESULT=0 >> "' .. logw .. '" 2>&1',
+        'if errorlevel 1 exit /b 22',
+        "exit /b 0",
+    }, "\r\n") .. "\r\n")
+
+    -- Outer script: find the toolset, then hand the actual build to the inner
+    -- script in a CHILD cmd and record its exit code.
+    --
+    -- The child process is the whole point. Three runs in a row died silently
+    -- right after `call "%VCVARS%"` succeeded — the log even showed
+    -- "[vcvarsall.bat] Environment initialized for: 'x64'" — and then nothing:
+    -- no further echo, no RESULT, exit 0. Visual Studio's developer-prompt
+    -- script terminates the batch that calls it. Running it inside `cmd /c
+    -- <inner.bat>` means it can only take that child down, and the outer
+    -- script still runs to write RESULT. The vcvars path travels by ENVIRONMENT
+    -- VARIABLE rather than as an argument, because a child cmd inherits the
+    -- environment and that avoids another layer of quoting around a path with
+    -- spaces.
+    io.writefile(bat, table.concat({
+        "@echo off",
+        'echo [bat] started >> "' .. logw .. '" 2>&1',
+        'set "VSWHERE=%ProgramFiles(x86)%\\Microsoft Visual Studio\\Installer\\vswhere.exe"',
+        'echo [bat] vswhere=%VSWHERE% >> "' .. logw .. '" 2>&1',
+        'if not exist "%VSWHERE%" ( echo [bat] RESULT=10 vswhere missing >> "' .. logw .. '" & exit /b 0 )',
+        'for /f "usebackq tokens=*" %%i in (`"%VSWHERE%" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath`) do set "VSPATH=%%i"',
+        'echo [bat] vspath=%VSPATH% >> "' .. logw .. '" 2>&1',
+        'if not defined VSPATH ( echo [bat] RESULT=11 no VC toolset >> "' .. logw .. '" & exit /b 0 )',
+        'set "MCPP_VCVARS=%VSPATH%\\VC\\Auxiliary\\Build\\vcvars64.bat"',
+        'if not exist "%MCPP_VCVARS%" ( echo [bat] RESULT=12 no vcvars64 >> "' .. logw .. '" & exit /b 0 )',
+        'echo [bat] handing build to child cmd >> "' .. logw .. '" 2>&1',
+        'cmd /c "' .. innerw .. '"',
+        'echo [bat] RESULT=%errorlevel% >> "' .. logw .. '" 2>&1',
         "exit /b 0",
     }, "\r\n") .. "\r\n")