Issue #3275324: If the PHP binary is not in the PHP interpreter's PATH, Composer invocations fail

package_manager/src/ProcessFactory.php

@@ -74,8 +74,12 @@ final class ProcessFactory implements ProcessFactoryInterface {
     if ($this->isComposerCommand($command)) {
       $env['COMPOSER_HOME'] = $this->getComposerHomePath();
     }
-    // Ensure that the directory with PHP's binaries is in the PATH.
-    $env['PATH'] = $this->getEnv('PATH') . ':' . PHP_BINDIR;
+    // Ensure that the directory containing the PHP interpreter is in the PATH.
+    // If the server is running the command-line interface, the directory of
+    // PHP_BINARY is more likely to be accurate; otherwise, the compile-time
+    // PHP_BINDIR is the better candidate.
+    $php_dir = PHP_SAPI === 'cli' ? dirname(PHP_BINARY) : PHP_BINDIR;
+    $env['PATH'] = $this->getEnv('PATH') . ':' . $php_dir;
     return $process->setEnv($env);
   }