Add more checks to DuplicateExpressionPlugin

Fixes phan#2691

.phan/plugins/DuplicateExpressionPlugin.php

@@ -282,18 +282,96 @@ public function visitConditional(Node $node)
             );
             return;
         }
-        if ($cond_node instanceof Node && $cond_node->kind === ast\AST_ISSET) {
-            if (ASTHasher::hash($cond_node->children['var']) === $true_node_hash) {
-                $this->emitPluginIssue(
-                    $this->code_base,
-                    $this->context,
-                    'PhanPluginDuplicateConditionalNullCoalescing',
-                    '"isset(X) ? X : Y" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was {CODE}',
-                    [ASTReverter::toShortString($cond_node->children['var'])]
-                );
+        if (!$cond_node instanceof Node) {
+            return;
+        }
+        switch ($cond_node->kind) {
+            case ast\AST_ISSET:
+                if (ASTHasher::hash($cond_node->children['var']) === $true_node_hash) {
+                    $this->warnDuplicateConditionalNullCoalescing('isset(X) ? X : Y', $node->children['true']);
+                }
+                break;
+            case ast\AST_BINARY_OP:
+                $this->checkBinaryOpOfConditional($cond_node, $true_node_hash);
+                break;
+            case ast\AST_UNARY_OP:
+                $this->checkUnaryOpOfConditional($cond_node, $true_node_hash);
+                break;
+        }
+    }
+
+    /**
+     * @param int|string $true_node_hash
+     */
+    private function checkBinaryOpOfConditional(Node $cond_node, $true_node_hash)
+    {
+        if ($cond_node->flags !== ast\flags\BINARY_IS_NOT_IDENTICAL) {
+            return;
+        }
+        $left_node = $cond_node->children['left'];
+        $right_node = $cond_node->children['right'];
+        if (self::isNullConstantNode($left_node)) {
+            if (ASTHasher::hash($right_node) === $true_node_hash) {
+                $this->warnDuplicateConditionalNullCoalescing('null !== X ? X : Y', $right_node);
+            }
+        } elseif (self::isNullConstantNode($right_node)) {
+            if (ASTHasher::hash($left_node) === $true_node_hash) {
+                $this->warnDuplicateConditionalNullCoalescing('X !== null ? X : Y', $left_node);
             }
         }
     }
+
+    /**
+     * @param int|string $true_node_hash
+     */
+    private function checkUnaryOpOfConditional(Node $cond_node, $true_node_hash)
+    {
+        if ($cond_node->flags !== ast\flags\UNARY_BOOL_NOT) {
+            return;
+        }
+        $expr = $cond_node->children['expr'];
+        if (!$expr instanceof Node) {
+            return;
+        }
+        if ($expr->kind === ast\AST_CALL) {
+            $function = $expr->children['expr'];
+            if ($function->kind !== ast\AST_NAME || strcasecmp((string)($function->children['name'] ?? ''), 'is_null') !== 0) {
+                return;
+            }
+            $args = $expr->children['args']->children;
+            if (count($args) !== 1) {
+                return;
+            }
+            if (ASTHasher::hash($args[0]) === $true_node_hash) {
+                $this->warnDuplicateConditionalNullCoalescing('!is_null(X) ? X : Y', $args[0]);
+            }
+        }
+    }
+
+    /**
+     * @param Node|mixed $node
+     */
+    private static function isNullConstantNode($node) : bool
+    {
+        if (!$node instanceof Node) {
+            return false;
+        }
+        return $node->kind === ast\AST_CONST && strcasecmp((string)$node->children['name']->children['name'] ?? '', 'null') === 0;
+    }
+
+    /**
+     * @param ?(Node|string|int|float) $x_node
+     */
+    private function warnDuplicateConditionalNullCoalescing(string $expr, $x_node)
+    {
+        $this->emitPluginIssue(
+            $this->code_base,
+            $this->context,
+            'PhanPluginDuplicateConditionalNullCoalescing',
+            '"' . $expr . '" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was {CODE}',
+            [ASTReverter::toShortString($x_node)]
+        );
+    }
 }
 
 // Every plugin needs to return an instance of itself at the

NEWS.md

@@ -13,6 +13,8 @@ New features(CLI, Configs):
 New features(Analysis):
 + Emit `PhanDeprecatedClassConstant` for code using a constant marked with `@deprecated`.
 
+Plugins:
++ Add more forms of checks such as `$x !== null ? $x : null` to `PhanPluginDuplicateConditionalNullCoalescing` (#2691)
 
 28 Apr 2019, Phan 1.3.2
 -----------------------

src/Phan/CLI.php

@@ -1429,7 +1429,8 @@ private static function isPathExcludedByRegex(
     }
 
     // Bound the percentage to [0, 1]
-    private static function boundPercentage(float $p) : float {
+    private static function boundPercentage(float $p) : float
+    {
         return \min(\max($p, 0.0), 1.0);
     }
 
@@ -1568,7 +1569,8 @@ public static function debugProgress(string $msg, float $p, $details)
     /**
      * @return void
      */
-    public static function debugOutput(string $line) {
+    public static function debugOutput(string $line)
+    {
         \fwrite(STDERR, $line . "\n");
     }
 

src/Phan/Debug/Frame.php

@@ -7,10 +7,10 @@
 use Phan\Language\Element\AddressableElement;
 use Phan\Language\Element\UnaddressableTypedElement;
 use Phan\Language\FQSEN;
-use Phan\Library\None;
-use Phan\Library\Some;
 use Phan\Language\Type;
 use Phan\Language\UnionType;
+use Phan\Library\None;
+use Phan\Library\Some;
 use Phan\Library\StringUtil;
 use function count;
 use function get_class;

tests/plugin_test/expected/118_more_isset_checks.php.expected

@@ -0,0 +1,5 @@
+src/118_more_isset_checks.php:2 PhanUnreferencedFunction Possibly zero references to function \example118()
+src/118_more_isset_checks.php:3 PhanPluginDuplicateConditionalNullCoalescing "isset(X) ? X : Y" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was $arg
+src/118_more_isset_checks.php:4 PhanPluginDuplicateConditionalNullCoalescing "!is_null(X) ? X : Y" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was $arg
+src/118_more_isset_checks.php:5 PhanPluginDuplicateConditionalNullCoalescing "X !== null ? X : Y" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was $arg
+src/118_more_isset_checks.php:6 PhanPluginDuplicateConditionalNullCoalescing "null !== X ? X : Y" can usually be simplified to "X ?? Y" in PHP 7. The duplicated expression X was $arg

tests/plugin_test/src/118_more_isset_checks.php

@@ -0,0 +1,7 @@
+<?php
+function example118(?string $arg) {
+    echo isset($arg) ? $arg : 'default';
+    echo !is_null($arg) ? $arg : 'default';
+    echo ($arg !== null) ? $arg : 'default';
+    echo (null !== $arg) ? $arg : 'default';
+}