Add way to find all references to a given class or method in the codebase

bin/psalm

@@ -24,7 +24,7 @@ $options = getopt(
     [
         'help', 'debug', 'config:', 'monochrome', 'show-info:', 'diff',
         'file:', 'self-check', 'update-docblocks', 'output-format:',
-        'find-dead-code', 'init',
+        'find-dead-code', 'init', 'find-references-to:',
     ]
 );
 
@@ -88,6 +88,9 @@ Options:
     --find-dead-code
         Look for dead code
 
+    --find-references-to=[class|method]
+        Searches the codebase for references to the given fully-qualified class or method,
+        where method is in the format class::methodName
 
 HELP;
 
@@ -237,6 +240,8 @@ $is_diff = isset($options['diff']);
 
 $find_dead_code = isset($options['find-dead-code']);
 
+$find_references_to = isset($options['find-references-to']) ? $options['find-references-to'] : null;
+
 $update_docblocks = isset($options['update-docblocks']);
 
 $project_checker = new ProjectChecker(
@@ -245,7 +250,8 @@ $project_checker = new ProjectChecker(
     $output_format,
     $debug,
     $update_docblocks,
-    $find_dead_code
+    $find_dead_code || $find_references_to !== null,
+    $find_references_to
 );
 
 // initialise custom config, if passed

src/Psalm/Checker/FunctionLikeChecker.php

@@ -407,7 +407,10 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
             }
         }
 
-        if ($context->collect_references && $context->check_variables) {
+        if ($context->collect_references &&
+            !$this->getFileChecker()->project_checker->find_references_to &&
+            $context->check_variables
+        ) {
             foreach ($context->vars_possibly_in_scope as $var_name => $_) {
                 if (strpos($var_name, '->') === false &&
                     $var_name !== '$this' &&

src/Psalm/Checker/ProjectChecker.php

@@ -54,6 +54,11 @@ class ProjectChecker
      */
     public $collect_references = false;
 
+    /**
+     * @var string|null
+     */
+    public $find_references_to;
+
     /**
      * @var bool
      */
@@ -176,7 +181,8 @@ class ProjectChecker
      * @param boolean $debug_output
      * @param string  $output_format
      * @param bool    $update_docblocks
-     * @param bool    $find_dead_code
+     * @param bool    $collect_references
+     * @param string  $find_references_to
      */
     public function __construct(
         $use_color = true,
@@ -184,13 +190,15 @@ class ProjectChecker
         $output_format = self::TYPE_CONSOLE,
         $debug_output = false,
         $update_docblocks = false,
-        $find_dead_code = false
+        $collect_references = false,
+        $find_references_to = null
     ) {
         $this->use_color = $use_color;
         $this->show_info = $show_info;
         $this->debug_output = $debug_output;
         $this->update_docblocks = $update_docblocks;
-        $this->collect_references = $find_dead_code;
+        $this->collect_references = $collect_references;
+        $this->find_references_to = $find_references_to;
 
         if (!in_array($output_format, [self::TYPE_CONSOLE, self::TYPE_JSON, self::TYPE_EMACS])) {
             throw new \UnexpectedValueException('Unrecognised output format ' . $output_format);
@@ -279,7 +287,31 @@ class ProjectChecker
         }
 
         if ($this->collect_references) {
-            $this->checkClassReferences();
+            if ($this->find_references_to) {
+                if (strpos($this->find_references_to, '::') !== false) {
+                    $locations = $this->findReferencesToMethod($this->find_references_to);
+                } else {
+                    $locations = $this->findReferencesToClassLike($this->find_references_to);
+                }
+
+                foreach ($locations as $location) {
+                    $snippet = $location->getSnippet();
+
+                    $snippet_bounds = $location->getSnippetBounds();
+                    $selection_bounds = $location->getSelectionBounds();
+
+                    $selection_start = $selection_bounds[0] - $snippet_bounds[0];
+                    $selection_length = $selection_bounds[1] - $selection_bounds[0];
+
+                    echo $location->file_name . ':' . $location->getLineNumber() . PHP_EOL .
+                        ($this->use_color
+                            ? substr($snippet, 0, $selection_start) .
+                            "\e[97;42m" . substr($snippet, $selection_start, $selection_length) .
+                            "\e[0m" . substr($snippet, $selection_length + $selection_start)
+                            : $snippet
+                        ) . PHP_EOL . PHP_EOL;
+                }
+            }
         }
 
         IssueBuffer::finish(true, (int)$start_checks, $this->visited_files);
@@ -325,6 +357,52 @@ class ProjectChecker
         }
     }
 
+    /**
+     * @param  string $method_id
+     * @return \Psalm\CodeLocation[]
+     */
+    public function findReferencesToMethod($method_id)
+    {
+        list($fq_class_name, $method_name) = explode('::', $method_id);
+
+        if (!isset(ClassLikeChecker::$storage[strtolower($fq_class_name)])) {
+            die('Class ' . $fq_class_name . ' cannot be found' . PHP_EOL);
+        }
+
+        $class_storage = ClassLikeChecker::$storage[strtolower($fq_class_name)];
+
+        if (!isset($class_storage->methods[strtolower($method_name)])) {
+            die('Method ' . $method_id . ' cannot be found' . PHP_EOL);
+        }
+
+        $method_storage = $class_storage->methods[strtolower($method_name)];
+
+        if ($method_storage->referencing_locations === null) {
+            die('No references found for ' . $method_id . PHP_EOL);
+        }
+
+        return $method_storage->referencing_locations;
+    }
+
+    /**
+     * @param  string $fq_class_name
+     * @return \Psalm\CodeLocation[]
+     */
+    public function findReferencesToClassLike($fq_class_name)
+    {
+        if (!isset(ClassLikeChecker::$storage[strtolower($fq_class_name)])) {
+            die('Class ' . $fq_class_name . ' cannot be found' . PHP_EOL);
+        }
+
+        $class_storage = ClassLikeChecker::$storage[strtolower($fq_class_name)];
+
+        if ($class_storage->referencing_locations === null) {
+            die('No references found for ' . $fq_class_name . PHP_EOL);
+        }
+
+        return $class_storage->referencing_locations;
+    }
+
     /**
      * @return void
      */

src/Psalm/Checker/Statements/Expression/CallChecker.php

@@ -697,12 +697,16 @@ class CallChecker
                     continue;
                 }
 
+                if ($var_id === '$this') {
+                    $does_class_exist = true;
+                } else {
                     $does_class_exist = ClassLikeChecker::checkFullyQualifiedClassLikeName(
                         $fq_class_name,
                         $statements_checker->getFileChecker(),
                         new CodeLocation($statements_checker->getSource(), $stmt->var),
                         $statements_checker->getSuppressedIssues()
                     );
+                }
 
                 if (!$does_class_exist) {
                     return $does_class_exist;