ClassMapGenerator: stabilize the heredoc/nowdoc stripping

src/Composer/Autoload/ClassMapGenerator.php

@@ -246,7 +246,22 @@ private static function findClasses($path)
         }
 
         // strip heredocs/nowdocs
-        $contents = preg_replace('{<<<[ \t]*([\'"]?)(\w+)\\1(?:\r\n|\n|\r)(?:.*(?=[\r\n]+[ \t]*\\2))[\r\n]+[ \t]*\\2(?=\s*[;,.)])}s', 'null', $contents);
+        $contents = preg_replace('{
+            # opening heredoc/nowdoc delimiter (word-chars)
+            <<<[ \t]*([\'"]?)(\w+)\\1
+            # needs to be followed by a newline
+            (?:\r\n|\n|\r)
+            # the meat of it, matching line by line until end delimiter
+            (?:
+                # a valid line is optional white-space (possessive match) not followed by the end delimiter, then anything goes for the rest of the line
+                [\t ]*+(?!\\2 [\t \r\n]*[;,.)])[^\r\n]*
+                # end of line(s)
+                [\r\n]+
+            )*
+            # end delimiter
+            [\t ]* \\2 (?=[\t \r\n]*[;,.)])
+        }x', 'null', $contents);
+
         // strip strings
         $contents = preg_replace('{"[^"\\\\]*+(\\\\.[^"\\\\]*+)*+"|\'[^\'\\\\]*+(\\\\.[^\'\\\\]*+)*+\'}s', 'null', $contents);
         // strip leading non-php code if needed

tests/Composer/Test/Autoload/ClassMapGeneratorTest.php

@@ -55,6 +55,9 @@ public function getTestCreateMapTests()
             'Foo\\LargeGap' => realpath(__DIR__) . '/Fixtures/classmap/LargeGap.php',
             'Foo\\MissingSpace' => realpath(__DIR__) . '/Fixtures/classmap/MissingSpace.php',
             'Foo\\StripNoise' => realpath(__DIR__) . '/Fixtures/classmap/StripNoise.php',
+            'Foo\\First' => realpath(__DIR__) . '/Fixtures/classmap/StripNoise.php',
+            'Foo\\Second' => realpath(__DIR__) . '/Fixtures/classmap/StripNoise.php',
+            'Foo\\Third' => realpath(__DIR__) . '/Fixtures/classmap/StripNoise.php',
             'Foo\\SlashedA' => realpath(__DIR__) . '/Fixtures/classmap/BackslashLineEndingString.php',
             'Foo\\SlashedB' => realpath(__DIR__) . '/Fixtures/classmap/BackslashLineEndingString.php',
             'Unicode\\↑\\↑' => realpath(__DIR__) . '/Fixtures/classmap/Unicode.php',

tests/Composer/Test/Autoload/Fixtures/classmap/StripNoise.php

@@ -19,8 +19,14 @@ class FailHeredocWhitespace
 }
 WHITESPACE . <<<  MARKERINTEXT
     In PHP < 7.3, the docblock marker could occur in the text as long as it did not occur at the very start of the line.
+class FailHeredocMarkerInText
+{
+}
 But, what are you blind McFly, it's there. How else do you explain that wreck out there? Doc, Doc. Oh, no. You're alive. Bullet proof vest, how did you know, I never got a chance to tell you. About all that talk about screwing up future events, the space time continuum. Okay, alright, I'll prove it to you.
     MARKERINTEXT
+class FailHeredocMarkerInText2
+{
+}
  Look at my driver's license, expires 1987. Look at my birthday, for crying out load I haven't even been born yet. And, look at this picture, my brother, my sister, and me. Look at the sweatshirt, Doc, class of 1984. Why do you keep following me around? Hey beat it, spook, this don't concern you.
 MARKERINTEXT . <<<"DOUBLEQUOTES"
 class FailHeredocDoubleQuotes
@@ -90,3 +96,27 @@ public function test_simple_string()
         return 'class FailSimpleString {}';
     }
 }
+
+// Issue #10067.
+abstract class First {
+    public function heredocDuplicateMarker(): void {
+        echo <<<DUPLICATE_MARKER
+
+        DUPLICATE_MARKER;
+    }
+}
+
+abstract class Second extends First {
+    public function heredocDuplicateMarker(): void {
+        echo <<<DUPLICATE_MARKER
+
+        DUPLICATE_MARKER;
+    }
+}
+
+abstract class Third extends First {
+    public function heredocMarkersOnlyWhitespaceBetween(): void {
+        echo <<<DUPLICATE_MARKER
+DUPLICATE_MARKER;
+    }
+}