[DO NOT MERGE] measurement for #693: which process exits, and the encoding build.ninja is written in

.github/measure-693/fixtures/bmn/build.mcpp

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+// A build program written the way most are: narrow getenv, a narrow path
+// into std::ofstream, the path printed back to mcpp as bytes.
+#include <cstdio>
+#include <cstdlib>
+#include <fstream>
+#include <string>
+
+int main() {
+    const char* out = std::getenv("MCPP_OUT_DIR");
+    if (!out) { std::fputs("no MCPP_OUT_DIR\n", stderr); return 1; }
+    std::string p = std::string(out) + "/gen.cpp";
+    std::ofstream f(p);
+    if (!f) { std::fprintf(stderr, "build.mcpp: cannot open %s\n", p.c_str()); return 2; }
+    f << "int gen_value() { return 42; }\n";
+    f.close();
+    std::printf("mcpp:generated=%s\n", p.c_str());
+    return 0;
+}

.github/measure-693/fixtures/bmn/mcpp.toml

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+[package]
+name    = "probe"
+version = "0.1.0"
+
+[toolchain]
+default = "llvm@20.1.7"

.github/measure-693/fixtures/bmn/src/main.cpp

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+#include <cstdio>
+
+int gen_value();
+
+int main() {
+    std::printf("gen_value=%d\n", gen_value());
+    return 0;
+}

.github/measure-693/fixtures/bmw/build.mcpp

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+// A build program that speaks UTF-8 whatever the process code page is: the
+// wide environment, a wide path into std::ofstream, UTF-8 bytes back to mcpp.
+// It stands in for a build program that carries a UTF-8 activeCodePage.
+#include <cstdio>
+#include <cstdlib>
+#include <filesystem>
+#include <fstream>
+#include <string>
+
+int main() {
+#ifdef _WIN32
+    const wchar_t* w = _wgetenv(L"MCPP_OUT_DIR");
+    if (!w) { std::fputs("no MCPP_OUT_DIR\n", stderr); return 1; }
+    std::filesystem::path out(w);
+#else
+    const char* n = std::getenv("MCPP_OUT_DIR");
+    if (!n) { std::fputs("no MCPP_OUT_DIR\n", stderr); return 1; }
+    std::filesystem::path out(n);
+#endif
+    auto p = out / "gen.cpp";
+    std::ofstream f(p);
+    if (!f) { std::fputs("build.mcpp: cannot open the generated file\n", stderr); return 2; }
+    f << "int gen_value() { return 42; }\n";
+    f.close();
+    auto u8 = p.generic_u8string();
+    std::printf("mcpp:generated=%s\n", reinterpret_cast<const char*>(u8.c_str()));
+    return 0;
+}

.github/measure-693/fixtures/bmw/mcpp.toml

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+[package]
+name    = "probe"
+version = "0.1.0"
+
+[toolchain]
+default = "llvm@20.1.7"

.github/measure-693/fixtures/bmw/src/main.cpp

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+#include <cstdio>
+
+int gen_value();
+
+int main() {
+    std::printf("gen_value=%d\n", gen_value());
+    return 0;
+}

.github/measure-693/fixtures/hello/mcpp.toml

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+[package]
+name    = "probe"
+version = "0.1.0"
+
+[toolchain]
+default = "llvm@20.1.7"

.github/measure-693/fixtures/hello/src/main.cpp

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+import std;
+
+int main() {
+    std::println("hello from a project whose path is not ASCII");
+    return 0;
+}

.github/measure-693/fixtures/plain/mcpp.toml

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+[package]
+name    = "probe"
+version = "0.1.0"

.github/measure-693/fixtures/plain/src/main.cpp

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+#include <cstdio>
+
+int main() {
+    std::puts("plain: a project whose path is not ASCII");
+    return 0;
+}

.github/measure-693/rsp.ps1

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+# Measurement for mcpp#693, round 5. TEMPORARY: this branch is never merged.
+#
+# Question:
+#   R1  In which encodings do the MSVC tools read a response file whose content
+#       is not ASCII? mcpp's compile, link and archive edges on Windows pass
+#       their arguments through response files that Ninja writes with the bytes
+#       of build.ninja, which are UTF-8 under the code page mcpp declares. The
+#       earlier rounds produced no response file with non-ASCII content.
+#
+# Each case writes one response file in one encoding and runs the tool on it.
+# Directories: an ASCII control, a name inside code page 1252 (U+00E9) and a
+# name outside it (U+6D4B U+8BD5). Encodings: UTF-8 without a BOM, UTF-8 with
+# a BOM, UTF-16LE with a BOM, and code page 1252. The last case runs the same
+# UTF-8-with-BOM content through Ninja's `rspfile_content`, as mcpp would write
+# it.
+#
+# Every observation is one `READING <id>: ...` line. Source is ASCII only.
+
+$ErrorActionPreference = 'Continue'
+$ProgressPreference = 'SilentlyContinue'
+[System.Text.Encoding]::RegisterProvider([System.Text.CodePagesEncodingProvider]::Instance)
+
+function Reading([string]$id, [string]$text) {
+    $line = "READING ${id}: $text"
+    Write-Host $line
+    if ($env:GITHUB_STEP_SUMMARY) {
+        Add-Content -LiteralPath $env:GITHUB_STEP_SUMMARY -Value ("    " + $line) -Encoding utf8
+    }
+}
+
+function Run([string]$exe, [string[]]$argv, [string]$cwd) {
+    $psi = [System.Diagnostics.ProcessStartInfo]::new()
+    $psi.FileName = $exe
+    foreach ($a in $argv) { [void]$psi.ArgumentList.Add($a) }
+    $psi.WorkingDirectory = $cwd
+    $psi.UseShellExecute = $false
+    $psi.RedirectStandardOutput = $true
+    $psi.RedirectStandardError = $true
+    $p = [System.Diagnostics.Process]::Start($psi)
+    $o = $p.StandardOutput.ReadToEndAsync(); $e = $p.StandardError.ReadToEndAsync()
+    $p.WaitForExit()
+    return @{ code = $p.ExitCode; out = ($o.Result + $e.Result) }
+}
+
+function FirstLine([string]$s) {
+    $t = ($s -replace "`r", '' -split "`n" | Where-Object { $_ -match '\S' } | Select-Object -First 1)
+    if ($null -eq $t) { return '(no output)' }
+    if ($t.Length -gt 150) { $t = $t.Substring(0, 150) + '...' }
+    return $t
+}
+
+$Utf8 = [System.Text.UTF8Encoding]::new($false)
+$Ansi = [System.Text.Encoding]::GetEncoding(1252)
+function Bytes([string]$text, [string]$enc) {
+    switch ($enc) {
+        'u8'    { return $Utf8.GetBytes($text) }
+        'u8bom' { return [byte[]](@(0xEF, 0xBB, 0xBF) + $Utf8.GetBytes($text)) }
+        'u16'   { return [byte[]](@(0xFF, 0xFE) + [System.Text.Encoding]::Unicode.GetBytes($text)) }
+        'ansi'  { return $Ansi.GetBytes($text) }
+    }
+}
+
+# ---------------------------------------------------------------------------
+# The Visual Studio environment
+
+$vswhere = Join-Path ${env:ProgramFiles(x86)} 'Microsoft Visual Studio\Installer\vswhere.exe'
+$vs = & $vswhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath
+Import-Module (Join-Path $vs 'Common7\Tools\Microsoft.VisualStudio.DevShell.dll')
+Enter-VsDevShell -VsInstallPath $vs -SkipAutomaticLocation -DevCmdArguments '-arch=x64 -host_arch=x64' | Out-Null
+$acp = (Get-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\Nls\CodePage').ACP
+$cl = (Get-Command cl.exe).Source
+$ninja = Get-Command ninja.exe -ErrorAction SilentlyContinue
+Reading 'env' "acp=$acp cl=$cl ninja=$(if ($ninja) { $ninja.Source } else { 'absent' })"
+$ver = Run $cl @() $env:TEMP
+Reading 'env.cl' (FirstLine $ver.out)
+
+$Root = 'C:\m'
+New-Item -ItemType Directory -Force -Path (Join-Path $Root 'a') | Out-Null
+$A = Join-Path $Root 'a'
+[System.IO.File]::WriteAllText((Join-Path $A 't.c'), "#include `"h.h`"`nint main(void) { return H_OK - 1; }`n")
+[System.IO.File]::WriteAllText((Join-Path $A 't0.c'), "int main(void) { return 0; }`n")
+$r = Run $cl @('/nologo', '/c', 't0.c', '/Fot0.obj') $A
+Reading 'setup.t0' "exit=$($r.code)"
+
+$Dirs = [ordered]@{
+    ascii = 'plain'
+    cafe  = 'caf' + [char]0x00E9
+    cjk   = [string][char]0x6D4B + [char]0x8BD5
+}
+foreach ($k in $Dirs.Keys) {
+    $d = Join-Path $Root $Dirs[$k]
+    New-Item -ItemType Directory -Force -Path (Join-Path $d 'inc'), (Join-Path $d 'src') | Out-Null
+    [System.IO.File]::WriteAllText((Join-Path $d 'inc\h.h'), "#define H_OK 1`n")
+    [System.IO.File]::WriteAllText((Join-Path $d 'src\s.c'), "int s(void) { return 0; }`n")
+}
+
+# ---------------------------------------------------------------------------
+# R1: one response file per tool, directory and encoding
+
+foreach ($k in $Dirs.Keys) {
+    $d = Join-Path $Root $Dirs[$k]
+    foreach ($enc in @('u8', 'u8bom', 'u16', 'ansi')) {
+        if ($enc -eq 'ansi' -and $k -eq 'cjk') { continue }   # not representable
+        $cases = [ordered]@{
+            'cl-include' = @{ exe = 'cl.exe';   text = "/nologo /c /I`"$d\inc`" /Fo`"$A\t-$k-$enc.obj`" `"$A\t.c`"`r`n";          out = "$A\t-$k-$enc.obj" }
+            'cl-source'  = @{ exe = 'cl.exe';   text = "/nologo /c `"$d\src\s.c`" /Fo`"$A\s-$k-$enc.obj`"`r`n";                 out = "$A\s-$k-$enc.obj" }
+            'link-out'   = @{ exe = 'link.exe'; text = "/nologo /OUT:`"$d\o-$enc.exe`" `"$A\t0.obj`"`r`n";                         out = "$d\o-$enc.exe" }
+            'lib-out'    = @{ exe = 'lib.exe';  text = "/nologo /OUT:`"$d\l-$enc.lib`" `"$A\t0.obj`"`r`n";                         out = "$d\l-$enc.lib" }
+        }
+        foreach ($c in $cases.Keys) {
+            $rsp = Join-Path $A "$c-$k-$enc.rsp"
+            [System.IO.File]::WriteAllBytes($rsp, (Bytes $cases[$c].text $enc))
+            $r = Run $cases[$c].exe @("@$rsp") $A
+            $made = Test-Path -LiteralPath $cases[$c].out
+            $note = if ($r.code -eq 0) { '' } else { ' | ' + (FirstLine $r.out) }
+            Reading "R1.$c.$k.$enc" "exit=$($r.code) output=$made$note"
+        }
+    }
+}
+
+# ---------------------------------------------------------------------------
+# R1n: the same UTF-8-with-BOM content, written by Ninja from `rspfile_content`
+
+if (-not $ninja) {
+    $zip = Join-Path $env:TEMP 'ninja.zip'
+    Invoke-WebRequest -Uri 'https://github.com/ninja-build/ninja/releases/download/v1.12.1/ninja-win.zip' -OutFile $zip -UseBasicParsing
+    Expand-Archive -LiteralPath $zip -DestinationPath (Join-Path $env:TEMP 'ninja') -Force
+    $ninjaExe = Join-Path $env:TEMP 'ninja\ninja.exe'
+} else { $ninjaExe = $ninja.Source }
+$wcp = Run $ninjaExe @('-t', 'wincodepage') $A
+Reading 'R1n.wincodepage' (FirstLine $wcp.out)
+foreach ($k in $Dirs.Keys) {
+    foreach ($bom in @('none', 'bom')) {
+        $d = Join-Path $Root $Dirs[$k]
+        $b = Join-Path $Root "n-$k-$bom"
+        New-Item -ItemType Directory -Force -Path $b | Out-Null
+        $prefix = if ($bom -eq 'bom') { [string][char]0xFEFF } else { '' }
+        $text = "ninja_required_version = 1.11`n" +
+                "rule cc`n  command = cl.exe @`$out.rsp`n  rspfile = `$out.rsp`n" +
+                "  rspfile_content = $prefix/nologo /c /I`"$($d -replace ':', '$$:')\inc`" `$in /Fo`$out`n" +
+                "build t.obj: cc $($A -replace ':', '$$:')\t.c`n"
+        [System.IO.File]::WriteAllBytes((Join-Path $b 'build.ninja'), $Utf8.GetBytes($text))
+        $r = Run $ninjaExe @('-C', $b) $Root
+        $note = if ($r.code -eq 0) { '' } else { ' | ' + (FirstLine ($r.out -replace '(?m)^\[.*\]\s*', '')) }
+        Reading "R1n.$k.$bom" "exit=$($r.code) output=$(Test-Path -LiteralPath (Join-Path $b 't.obj'))$note"
+    }
+}
+
+# ---------------------------------------------------------------------------
+# R2: where rc.exe and windres look for a file named by a resource statement.
+# The script sits in res/, the file beside it, and the tool runs from another
+# directory with /I (or -I) naming the project root, as mcpp runs it.
+
+$P = Join-Path $Root 'rcproj'
+New-Item -ItemType Directory -Force -Path (Join-Path $P 'res'), (Join-Path $P 'out') | Out-Null
+[System.IO.File]::WriteAllText((Join-Path $P 'res\m.manifest'), "<?xml version=`"1.0`"?><assembly xmlns=`"urn:schemas-microsoft-com:asm.v1`" manifestVersion=`"1.0`"/>`n")
+[System.IO.File]::WriteAllText((Join-Path $P 'res\beside.rc'), "1 24 `"m.manifest`"`n")
+[System.IO.File]::WriteAllText((Join-Path $P 'res\rooted.rc'), "1 24 `"res/m.manifest`"`n")
+$O = Join-Path $P 'out'
+foreach ($f in @('beside', 'rooted')) {
+    $r = Run 'rc.exe' @('/nologo', '/C', '65001', "/I$P", '/fo', "$O\$f.res", "$P\res\$f.rc") $O
+    Reading "R2.rc.$f" "exit=$($r.code)$(if ($r.code -ne 0) { ' | ' + (FirstLine $r.out) })"
+}
+$windres = Get-Command windres.exe -ErrorAction SilentlyContinue
+if ($windres) {
+    foreach ($f in @('beside', 'rooted')) {
+        $r = Run $windres.Source @('-O', 'coff', '--codepage=65001', "-I$P", '-o', "$O\$f.o", "$P\res\$f.rc") $O
+        Reading "R2.windres.$f" "exit=$($r.code)$(if ($r.code -ne 0) { ' | ' + (FirstLine $r.out) })"
+    }
+} else { Reading 'R2.windres' 'absent' }