Keep an optional path as written where a plain one would be (#6452)

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: SanderMuller

.github/workflows/e2e-tests.yml

@@ -847,6 +847,21 @@ jobs:
               OUTPUT=$(../bashunit -a exit_code "0" "../../bin/phpstan analyse -vv")
               echo "$OUTPUT"
               ../bashunit -a contains 'Result cache restored. 0 files will be reanalysed.' "$OUTPUT"
+          - script: |
+              cd e2e/result-cache-relative-path
+              # An optional excludePath must reach the cache the way a required one does. It used to
+              # be absolutized whatever the loader was asked to expand, so it landed in the metadata
+              # as an absolute path and a checkout at another path discarded the whole cache.
+              ../../bin/phpstan analyse -c phpstan-optional-path.neon
+              if grep -q "$(cd ../.. && pwd)/" tmp-optional-path/resultCache.php; then
+                echo 'cache still holds absolute paths under the checkout:'
+                grep -o "$(cd ../.. && pwd)/[^'\"]*" tmp-optional-path/resultCache.php | sort -u | head -20
+                exit 1
+              fi
+              OUTPUT=$(../bashunit -a exit_code "0" "../../bin/phpstan analyse -c phpstan-optional-path.neon -vv")
+              echo "$OUTPUT"
+              ../bashunit -a contains 'Result cache restored. 0 files will be reanalysed.' "$OUTPUT"
+
           - script: |
               cd e2e/result-cache-relative-path
               MAIN="$(pwd)"

e2e/result-cache-relative-path/.gitignore

@@ -1 +1,2 @@
 /tmp
+/tmp-optional-path

e2e/result-cache-relative-path/optional-src/ExcludedWithError.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types = 1);
+
+namespace ResultCacheRelativePath\OptionalSrc;
+
+// Reported at level 8 unless the optional excludePath keeps this directory out of the analysis,
+// so the scenario fails if the entry stops excluding.
+class ExcludedWithError
+{
+
+	public function getName(): string
+	{
+		return 1;
+	}
+
+}

e2e/result-cache-relative-path/phpstan-optional-path.neon

@@ -0,0 +1,24 @@
+# The same sources as phpstan.neon plus optional-src/, with optional excludePaths added.
+# `- path (?)` used to be absolutized whatever the loader was asked to expand, so it reached the
+# result cache metadata as an absolute path while the required entries stayed as written.
+#
+# One entry points at a directory that exists and holds an error, so the scenario fails if the
+# entry stops excluding. The other points at nothing, which is what `(?)` is for.
+#
+# Its own tmpDir: two configs sharing one would write the same %tmpDir%/resultCache.php and discard
+# each other's cache, which is https://github.com/phpstan/phpstan/issues/15232 and not what this
+# scenario is about.
+parameters:
+    level: 8
+    tmpDir: tmp-optional-path
+    paths:
+        - src
+        - optional-src
+    excludePaths:
+        analyse:
+            - optional-src (?)
+            - src/NotThere (?)
+    ignoreErrors:
+        -
+            identifier: booleanNot.alwaysFalse
+            path: src/TraitWithConstantCondition.php

src/DependencyInjection/NeonAdapter.php

@@ -161,6 +161,15 @@ private function createOptionalPath(string $keyToResolve, Entity $entity, string
 			return null;
 		}
 
+		// Expanded and absolutized only where a plain path entry under the same key would be. A
+		// loader given a narrower list - CommandHelper reads the project config for the result cache
+		// metadata with only paths and tmpDir in it - keeps the value exactly as written, so the
+		// optional entry and the required one beside it are stored the same way and a move of the
+		// anchor directory leaves both alone.
+		if (!in_array($keyToResolve, $this->expandRelativePaths, true)) {
+			return new OptionalPath($entity->value);
+		}
+
 		$path = $this->expandKnownParameters($entity->value);
 		if ($path === null) {
 			return null;