infer_clone/infer/lib/linter_rules/linters.al

// Copyright (c) Facebook, Inc. and its affiliates.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.

// DIRECT_ATOMIC_PROPERTY_ACCESS:
// a property declared atomic should not be accessed directly via its ivar
DEFINE-CHECKER DIRECT_ATOMIC_PROPERTY_ACCESS = {

	SET report_when =
	  WHEN
			((NOT context_in_synchronized_block()) AND is_ivar_atomic())
			AND NOT is_method_property_accessor_of_ivar()
			AND NOT is_objc_constructor()
			AND NOT is_objc_dealloc()
		HOLDS-IN-NODE ObjCIvarRefExpr;

  	SET message = "Direct access to ivar %ivar_name% of an atomic property";
  	SET suggestion = "Accessing an ivar of an atomic property makes the property nonatomic.";
	  SET severity = "WARNING";
};

// ASSIGN_POINTER_WARNING:
// a property with a pointer type should not be declared `assign`
DEFINE-CHECKER ASSIGN_POINTER_WARNING = {

	 SET report_when =
	    WHEN
	  		is_assign_property() AND is_property_pointer_type()
      HOLDS-IN-NODE ObjCPropertyDecl;

	 SET message = "Property %decl_name% is a pointer type marked with the `assign` attribute";
	 SET suggestion = "Use a different attribute like `strong` or `weak`.";
	 SET severity = "WARNING";
};

// BAD_POINTER_COMPARISON:
// Fires whenever a NSNumber is dangerously coerced to a boolean in a comparison
DEFINE-CHECKER BAD_POINTER_COMPARISON = {

	LET bool_op =
		is_binop_with_kind("LAnd") OR is_binop_with_kind("LOr")
		OR is_unop_with_kind("LNot") OR is_unop_with_kind("LNot");

  LET comparison_with_integral =
	  ( is_binop_with_kind("EQ") OR is_binop_with_kind("NE")
			OR is_binop_with_kind("GT") OR is_binop_with_kind("GE")
			OR is_binop_with_kind("LT") OR is_binop_with_kind("LE"))
		AND
		( (is_node("ImplicitCastExpr") AND has_type("NSNumber *")
			AND has_cast_kind("IntegralToPointer")
		) HOLDS-NEXT);

	LET root_is_stmt_expecting_bool =
		is_node("IfStmt") OR is_node("ForStmt") OR is_node("WhileStmt");

	LET use_num_as_bool =
		(bool_op OR root_is_stmt_expecting_bool) AND (has_type("NSNumber *") HOLDS-NEXT);

	LET bad_conditional =
	  is_node("ConditionalOperator") AND (has_type("NSNumber *") HOLDS-NEXT WITH-TRANSITION Cond);

	SET report_when =
		use_num_as_bool OR comparison_with_integral OR bad_conditional;

  SET message = "Implicitly checking whether NSNumber pointer is nil or comparing to integral value";

	SET suggestion =
		"Did you mean to use/compare against the unboxed value instead? Please either explicitly compare the NSNumber instance to nil, or use one of the NSNumber accessors before the comparison.";
};


DEFINE-CHECKER REGISTERED_OBSERVER_BEING_DEALLOCATED = {

	LET exists_method_calling_addObserver =
		 call_method("addObserver:selector:name:object:") HOLDS-EVENTUALLY;

	LET exists_method_calling_addObserverForName =
	   call_method("addObserverForName:object:queue:usingBlock:") HOLDS-EVENTUALLY;

	LET add_observer =
	   exists_method_calling_addObserver OR exists_method_calling_addObserverForName;

  LET eventually_addObserver =
	    IN-NODE ObjCMethodDecl WITH-TRANSITION Body
			 		(add_observer)
			 HOLDS-EVENTUALLY;

	LET exists_method_calling_removeObserver =
	     call_method("removeObserver:") HOLDS-EVENTUALLY;

	LET exists_method_calling_removeObserverName =
		  call_method("removeObserver:name:object:") HOLDS-EVENTUALLY;

	LET remove_observer =
				exists_method_calling_removeObserver OR exists_method_calling_removeObserverName;

	LET remove_observer_in_block =
				IN-NODE BlockDecl WITH-TRANSITION Body
						(remove_observer)
				HOLDS-EVENTUALLY;

 	LET remove_observer1 =
 				remove_observer OR remove_observer_in_block;

  LET remove_observer_in_method =
  	IN-NODE ObjCMethodDecl WITH-TRANSITION Body
	  		(remove_observer1)
		HOLDS-EVENTUALLY;

	LET eventually_removeObserver =
		IN-NODE ObjCImplementationDecl, ObjCProtocolDecl WITH-TRANSITION Any
		 		(remove_observer_in_method  OR
					remove_observer_in_method HOLDS-IN-SOME-SUPERCLASS-OF ObjCImplementationDecl)
 	HOLDS-EVENTUALLY;

  SET report_when =
			WHEN
	    	NOT (eventually_addObserver IMPLIES eventually_removeObserver) AND
				NOT iphoneos_target_sdk_version_greater_or_equal("9.0") //this is not needed after iOS SDK 9.0
			HOLDS-IN-NODE ObjCImplementationDecl, ObjCProtocolDecl;

	SET message =
		"Object self is registered in a notification center but not being removed before deallocation";

	SET suggestion =
		"Consider removing the object from the notification center before its deallocation.";

};

DEFINE-CHECKER STRONG_DELEGATE_WARNING = {

  LET name_contains_delegate = declaration_has_name(REGEXP("[dD]elegate"));
  LET name_does_not_contain_delegates =
					NOT declaration_has_name(REGEXP("[dD]elegates"));
  LET name_does_not_contains_queue =
					NOT declaration_has_name(REGEXP("[qQ]ueue"));

  SET report_when =
	    WHEN
				name_contains_delegate AND name_does_not_contain_delegates AND name_does_not_contains_queue AND is_strong_property()
			HOLDS-IN-NODE ObjCPropertyDecl;

  SET message = "Property or ivar %decl_name% declared strong";
  SET suggestion = "In general delegates should be declared weak or assign.";

};

DEFINE-CHECKER GLOBAL_VARIABLE_INITIALIZED_WITH_FUNCTION_OR_METHOD_CALL = {

  LET is_global_but_not_const_variable =
     is_objc_extension() AND is_global_var() AND (NOT is_const_expr_var()) AND (NOT is_init_integral_constant_expr());

	LET makes_an_expensive_call =
	 (is_node("CallExpr") AND NOT call_function("CGPointMake"))
		OR is_node("CXXTemporaryObjectExpr")
    OR is_node("CXXMemberCallExpr")
    OR is_node("CXXOperatorCallExpr")
    OR is_node("ObjCMessageExpr");

  LET is_initialized_with_expensive_call  =
    IN-NODE VarDecl WITH-TRANSITION InitExpr
		  (makes_an_expensive_call HOLDS-EVENTUALLY)
		HOLDS-EVENTUALLY;

  SET report_when =
	   WHEN
     		(is_global_but_not_const_variable AND is_initialized_with_expensive_call)
		 HOLDS-IN-NODE VarDecl;

  SET message =
       "Global variable %decl_name% is initialized using a function or method call";
  SET suggestion =
        "If the function/method call is expensive, it can affect the starting time of the app.";
};


DEFINE-CHECKER CXX_REFERENCE_CAPTURED_IN_OBJC_BLOCK = {

		// The current node is block definition capturing a C++ reference
		LET capture_reference =
 			WHEN
				((is_node("BlockDecl") AND captures_cxx_references()) HOLDS-NEXT)
 			HOLDS-IN-NODE BlockExpr;

 		// At some point we encounter a block definition capturing a C++ reference
 		LET block_definition_capture_reference =
			capture_reference HOLDS-EVENTUALLY;

		// A variable definition initialized with a block capturing a C++ reference
 		LET variable_initialized_with_block =
		IN-NODE VarDecl WITH-TRANSITION InitExpr
			(block_definition_capture_reference)
 		HOLDS-EVENTUALLY;

 		// Reference to a variable initialized with a capturing block
 		LET variable_block_definition =
			IN-NODE DeclRefExpr WITH-TRANSITION PointerToDecl
				(variable_initialized_with_block)
			HOLDS-EVENTUALLY;

		// Report when a function that does not have NoEscapeAttribute call a block or a variable definied with
		// a block capturing a C++ ref
		SET report_when =
			WHEN
				(NOT has_no_escape_attribute) AND (block_definition_capture_reference OR variable_block_definition)
			HOLDS-IN-NODE CallExpr;

	  SET message =
	        "C++ Reference variable(s) %cxx_ref_captured_in_block% captured by Objective-C block";

	  SET suggestion = "This will very likely cause a crash because C++ References are unmanaged and may be invalid by the time the block executes.";

    SET severity = "ERROR";
		SET mode = "ON";
	};

	// If the declaration has availability attributes, check that it's compatible with
	// the iphoneos_target_sdk_version
	DEFINE-CHECKER UNAVAILABLE_API_IN_SUPPORTED_IOS_SDK = {

		SET report_when =
		     WHEN HOLDS-NEXT WITH-TRANSITION PointerToDecl
	 				 (decl_unavailable_in_supported_ios_sdk() AND
	 				 NOT within_responds_to_selector_block())
				 HOLDS-IN-NODE DeclRefExpr, ObjCMessageExpr;

		  SET message =
		        "%decl_ref_or_selector_name% is not available in the required iOS SDK version %iphoneos_target_sdk_version% (only available from version %available_ios_sdk%)";
      SET name = "Unavailable API In Supported iOS SDK";
		  SET suggestion = "This could cause a crash.";
			SET severity = "ERROR";
		};

	DEFINE-CHECKER UNAVAILABLE_CLASS_IN_SUPPORTED_IOS_SDK = {
		SET report_when =
				 WHEN ((class_unavailable_in_supported_ios_sdk()) AND
				       NOT within_available_class_block() AND
							 (call_class_method("alloc") OR
							 call_class_method("new")))
				 HOLDS-IN-NODE ObjCMessageExpr;

			SET message =
						"The receiver %receiver_method_call% of %name% is not available in the required iOS SDK version %iphoneos_target_sdk_version% (only available from version %class_available_ios_sdk%)";
			SET name = "Unavailable API In Supported iOS SDK";
			SET severity = "ERROR";
			SET mode = "ON";
		};


DEFINE-CHECKER POINTER_TO_INTEGRAL_IMPLICIT_CAST = {
  SET report_when =
      WHEN has_cast_kind("PointerToIntegral")
      HOLDS-IN-NODE ImplicitCastExpr;
  SET message = "Implicit conversion from %child_type% to %type% in usage of %name%";
	SET doc_url = "https://clang.llvm.org/docs/DiagnosticsReference.html#wint-conversion";
};

DEFINE-CHECKER POINTER_TO_CONST_OBJC_CLASS = {
  SET name = "Pointer To const Objective-C Class";
  SET report_when = is_decl() AND has_type_const_ptr_to_objc_class();
  SET message = "`const %class_name%*` may not mean what you want:
                   it represents a mutable pointer pointing to an Objective-C
                   class where the ivars cannot be changed.";
  SET suggestion = "Consider using `%class_name% *const` instead, meaning
	                  the destination of the pointer cannot be changed.";
  SET severity = "WARNING";
  SET mode = "ON";
};


DEFINE-CHECKER DISCOURAGED_WEAK_PROPERTY_CUSTOM_SETTER = {
  LET has_body = HOLDS-NEXT WITH-TRANSITION Body (TRUE);
  LET is_weak_property_setter =
    HOLDS-NEXT WITH-TRANSITION AccessorForProperty "setter" (
      is_weak_property()
    );
  SET report_when =
    WHEN
      has_body AND
      is_weak_property_setter
    HOLDS-IN-NODE ObjCMethodDecl;
  SET message = "Custom setters are not called when ARC sets weak properties to nil.";
  SET severity = "WARNING";
  SET mode = "OFF";
};

DEFINE-CHECKER WRONG_SCOPE_FOR_DISPATCH_ONCE_T = {

  SET report_when =
	    WHEN
			  NOT (is_global_var() OR is_static_local_var()) AND
				has_type("dispatch_once_t")
			HOLDS-IN-NODE VarDecl;

		SET message = "Variables of type dispatch_once_t must have global or static scope. The result of using this type with automatic or dynamic allocation is undefined.";
		SET severity = "WARNING";
		SET mode = "ON";
};


DEFINE-CHECKER UNSAFE_CALL_TO_OPTIONAL_METHOD = {

  SET report_when =
   WHEN
     is_call_to_optional_objc_method
     AND
     (NOT objc_method_call_within_responds_to_selector_block)
  HOLDS-IN-NODE ObjCMessageExpr;

  SET message = "This is a call to an `@optional` protocol method. Calling it without checking if its implemented can lead to crashes at run time.";
	SET suggestion = "Please make sure to test the method is implemented by first calling `if ([object respondsToSelector:@selector(%decl_name%)]) ...` ";
	SET severity = "ERROR";
	SET mode = "ON";

};