Roll-forward #164317: Use bin/cache/engine.stamp (#164401)

... and this time, create `bin/cache` before trying to write to it!

(Tests updated to catch this regression)

Author: matanlurey

.gitignore

@@ -1,9 +1,6 @@
 # Do not remove or rename entries in this file, only add new ones
 # See https://github.com/flutter/flutter/issues/128635 for more context.
 
-# This is dynamic in a monorepo
-bin/internal/engine.version
-
 # Miscellaneous
 *.class
 *.lock
@@ -33,6 +30,8 @@ bin/internal/engine.version
 /bin/cache/
 /bin/internal/bootstrap.bat
 /bin/internal/bootstrap.sh
+/bin/internal/engine.realm
+/bin/internal/engine.version
 /bin/mingit/
 /dev/benchmarks/mega_gallery/
 /dev/bots/.recipe_deps

bin/internal/engine.realm

@@ -19,9 +19,13 @@ $ErrorActionPreference = "Stop"
 $progName = Split-Path -parent $MyInvocation.MyCommand.Definition
 $flutterRoot = (Get-Item $progName).parent.parent.FullName
 
+# Generate a bin/cache directory, which won't initially exist for a fresh checkout.
+New-Item -Path "$flutterRoot/bin/cache" -ItemType Directory -Force | Out-Null
+
 # On stable, beta, and release tags, the engine.version is tracked by git - do not override it.
 $trackedEngine = (git -C "$flutterRoot" ls-files bin/internal/engine.version) | Out-String
 if ($trackedEngine.length -ne 0) {
+  Copy-Item -Path "$flutterRoot/bin/internal/engine.version" -Destination "$flutterRoot/bin/cache/engine.stamp" -Force
   return
 }
 
@@ -40,7 +44,7 @@ if (![string]::IsNullOrEmpty($env:FLUTTER_PREBUILT_ENGINE_VERSION)) {
 }
 
 # Test for fusion repository
-if ([string]::IsNullOrEmpty($engineVersion) -and (Test-Path "$flutterRoot\DEPS" -PathType Leaf) -and (Test-Path "$flutterRoot\engine\src\.gn" -PathType Leaf)) {
+if ([string]::IsNullOrEmpty($engineVersion) -and (Test-Path "$flutterRoot/DEPS" -PathType Leaf) -and (Test-Path "$flutterRoot/engine/src/.gn" -PathType Leaf)) {
     if ($null -eq $Env:LUCI_CONTEXT) {
         $ErrorActionPreference = "Continue"
         git -C "$flutterRoot" remote get-url upstream *> $null
@@ -59,9 +63,17 @@ if ([string]::IsNullOrEmpty($engineVersion) -and (Test-Path "$flutterRoot\DEPS"
 
 # Write the engine version out so downstream tools know what to look for.
 $utf8NoBom = New-Object System.Text.UTF8Encoding($false)
-[System.IO.File]::WriteAllText("$flutterRoot\bin\internal\engine.version", $engineVersion, $utf8NoBom)
+[System.IO.File]::WriteAllText("$flutterRoot/bin/cache/engine.stamp", $engineVersion, $utf8NoBom)
+# TODO(matanlurey): Stop writing to internal/engine.version. https://github.com/flutter/flutter/issues/164315.
+[System.IO.File]::WriteAllText("$flutterRoot/bin/internal/engine.version", $engineVersion, $utf8NoBom)
 
 # The realm on CI is passed in.
 if ($Env:FLUTTER_REALM) {
-    [System.IO.File]::WriteAllText("$flutterRoot\bin\internal\engine.realm", $Env:FLUTTER_REALM, $utf8NoBom)
+    [System.IO.File]::WriteAllText("$flutterRoot/bin/cache/engine.realm", $Env:FLUTTER_REALM, $utf8NoBom)
+    # TODO(matanlurey): Stop writing to internal/engine.realm. https://github.com/flutter/flutter/issues/164315.
+    [System.IO.File]::WriteAllText("$flutterRoot/bin/internal/engine.realm", $Env:FLUTTER_REALM, $utf8NoBom)
+} else {
+    [System.IO.File]::WriteAllText("$flutterRoot/bin/cache/engine.realm", "", $utf8NoBom)
+    # TODO(matanlurey): Stop writing to internal/engine.realm. https://github.com/flutter/flutter/issues/164315.
+    [System.IO.File]::WriteAllText("$flutterRoot/bin/internal/engine.realm", "", $utf8NoBom)
 }

bin/internal/update_engine_version.ps1

@@ -33,9 +33,13 @@ fi
 
 FLUTTER_ROOT="$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")"
 
+# Generate a bin/cache directory, which won't initially exist for a fresh checkout.
+mkdir -p "$FLUTTER_ROOT/bin/cache"
+
 # On stable, beta, and release tags, the engine.version is tracked by git - do not override it.
 TRACKED_ENGINE="$(git -C "$FLUTTER_ROOT" ls-files bin/internal/engine.version)"
 if [[ -n "$TRACKED_ENGINE" ]]; then
+  cp $FLUTTER_ROOT/bin/internal/engine.version $FLUTTER_ROOT/bin/cache/engine.stamp
   exit
 fi
 
@@ -60,9 +64,17 @@ if [ -z "$ENGINE_VERSION" ] && [ -f "$FLUTTER_ROOT/DEPS" ] && [ -f "$FLUTTER_ROO
 fi
 
 # Write the engine version out so downstream tools know what to look for.
+echo $ENGINE_VERSION > "$FLUTTER_ROOT/bin/cache/engine.stamp"
+# TODO(matanlurey): Stop writing to internal/engine.version. https://github.com/flutter/flutter/issues/164315.
 echo $ENGINE_VERSION > "$FLUTTER_ROOT/bin/internal/engine.version"
 
 # The realm on CI is passed in.
 if [ -n "${FLUTTER_REALM}" ]; then
+  echo $FLUTTER_REALM > "$FLUTTER_ROOT/bin/cache/engine.realm"
+  # TODO(matanlurey): Stop writing to internal/engine.realm. https://github.com/flutter/flutter/issues/164315.
   echo $FLUTTER_REALM > "$FLUTTER_ROOT/bin/internal/engine.realm"
+else
+  echo "" > "$FLUTTER_ROOT/bin/cache/engine.realm"
+  # TODO(matanlurey): Stop writing to internal/engine.realm. https://github.com/flutter/flutter/issues/164315.
+  echo "" > "$FLUTTER_ROOT/bin/internal/engine.realm"
 fi