Store the result cache in a framed serialize() format instead of a var_export'd PHP file

.github/workflows/e2e-tests.yml

@@ -161,6 +161,40 @@ jobs:
               echo "$OUTPUT"
               ../bashunit -a contains 'Result cache restored. 0 files will be reanalysed.' "$OUTPUT"
               ../bashunit -a not_contains 'metadata do not match' "$OUTPUT"
+          - script: |
+              cd e2e/result-cache-truncated
+              ../../bin/phpstan -vvv
+              # Cut inside the first section's payload: the cache is damaged, not merely stale, so
+              # it has to be discarded rather than read as far as it goes.
+              php truncate.php
+              OUTPUT=$(../../bin/phpstan -vvv 2>&1)
+              echo "$OUTPUT"
+              ../bashunit -a contains 'an error occurred while loading the cache file' "$OUTPUT"
+              ../bashunit -a contains 'Result cache is saved.' "$OUTPUT"
+              # And once more inside a section that is read lazily, which is a different code path.
+              php truncate-lazy.php
+              OUTPUT=$(../../bin/phpstan -vvv 2>&1)
+              echo "$OUTPUT"
+              ../bashunit -a contains 'is truncated at entry' "$OUTPUT"
+              OUTPUT=$(../../bin/phpstan -vvv 2>&1)
+              echo "$OUTPUT"
+              ../bashunit -a contains 'Result cache restored.' "$OUTPUT"
+          - script: |
+              cd e2e/result-cache-stale-objects
+              OUTPUT=$(../bashunit -a exit_code "1" "../../bin/phpstan -vvv")
+              echo "$OUTPUT"
+              # Renaming a property inside the cache file is what a cache written by a PHPStan whose
+              # classes have changed since looks like: the payload does not carry the property the class
+              # now declares, so reconstructing the object leaves it uninitialized and reading it throws.
+              php rename-property.php
+              OUTPUT=$(../bashunit -a exit_code "1" "../../bin/phpstan -vvv")
+              echo "$OUTPUT"
+              ../bashunit -a contains 'could not be read back' "$OUTPUT"
+              ../bashunit -a contains 'Result cache is saved.' "$OUTPUT"
+              # The cache written in its place is usable again.
+              OUTPUT=$(../bashunit -a exit_code "1" "../../bin/phpstan -vvv")
+              echo "$OUTPUT"
+              ../bashunit -a contains 'Result cache restored.' "$OUTPUT"
           - script: |
               cd e2e/bug-14514
               composer install

.gitignore

@@ -20,3 +20,5 @@ e2e/bashunit
 /e2e/result-cache-atomic-save/tmp
 /e2e/result-cache-moved-tmpdir/tmp-a
 /e2e/result-cache-moved-tmpdir/tmp-b
+/e2e/result-cache-stale-objects/tmp
+/e2e/result-cache-truncated/tmp

e2e/result-cache-stale-objects/phpstan.neon

@@ -0,0 +1,5 @@
+parameters:
+	level: 8
+	tmpDir: tmp
+	paths:
+		- src

e2e/result-cache-stale-objects/rename-property.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types = 1);
+
+// A cache written by a PHPStan whose classes have changed since cannot be reconstructed: the payload
+// does not carry the property the class now declares, so the object comes back with it uninitialized
+// and reading it throws. Renaming one inside the cache file is that shape without needing two
+// PHPStan versions installed, and keeping the byte length identical leaves the rest of the payload
+// valid - the frame headers count bytes.
+$file = __DIR__ . '/tmp/resultCache.php';
+$contents = file_get_contents($file);
+if ($contents === false) {
+	throw new RuntimeException('No result cache at ' . $file);
+}
+
+// Error::$message, read by transformPaths() while the cached errors are absolutized.
+$property = "\0PHPStan\\Analyser\\Error\0message";
+if (substr_count($contents, $property) !== 1) {
+	throw new RuntimeException('Expected exactly one cached Error carrying that property.');
+}
+
+$renamed = substr($property, 0, -strlen('message')) . 'messagf';
+if (strlen($renamed) !== strlen($property)) {
+	throw new RuntimeException('The replacement has to keep the byte length.');
+}
+
+file_put_contents($file, str_replace($property, $renamed, $contents));

e2e/result-cache-stale-objects/src/Foo.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace ResultCacheE2EStaleObjects;
+
+class Foo
+{
+
+	public function doFoo(): int
+	{
+		return 'not an int';
+	}
+
+}

e2e/result-cache-stale-objects/tmp/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

e2e/result-cache-truncated/phpstan.neon

@@ -0,0 +1,5 @@
+parameters:
+	level: 8
+	tmpDir: tmp
+	paths:
+		- src

e2e/result-cache-truncated/src/Bar.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace TestResultCacheTruncated;
+
+class Bar
+{
+
+	public function doBar(): string
+	{
+		return 'bar';
+	}
+
+}

e2e/result-cache-truncated/src/Foo.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace TestResultCacheTruncated;
+
+class Foo
+{
+
+	public function doFoo(Bar $bar): string
+	{
+		return $bar->doBar();
+	}
+
+}

e2e/result-cache-truncated/truncate-lazy.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+// The same shape as truncate.php, but cutting far enough in to land inside one of the sections
+// restore() reads lazily. Those are walked rather than decoded when the cache is opened, and
+// fseek() past the end of a file succeeds, so only comparing the position with the file size
+// catches this - otherwise the section would be handed out as a callback pointing past the end.
+$file = __DIR__ . '/tmp/resultCache.php';
+$contents = file_get_contents($file);
+if ($contents === false) {
+	throw new RuntimeException('No result cache at ' . $file);
+}
+
+file_put_contents($file, substr($contents, 0, (int) (strlen($contents) * 0.9)));

e2e/result-cache-truncated/truncate.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+// A cache file that is this format but incomplete: a CI cache artifact that was archived or
+// restored half way, a disk that filled up under something else, a copy that was interrupted.
+// Cutting inside the first section's payload is the shape that would otherwise be read as a
+// half-populated cache rather than a damaged one.
+$file = __DIR__ . '/tmp/resultCache.php';
+$contents = file_get_contents($file);
+if ($contents === false) {
+	throw new RuntimeException('No result cache at ' . $file);
+}
+
+file_put_contents($file, substr($contents, 0, 200));