gecko-dev/mfbt/StaticAnalysisFunctions.h
Emilio Cobos Álvarez 80439edf68 Bug 1699844 - Add an escape hatch for the refcounted inside lambda checker. r=andi
Allow using the MOZ_KnownLive function to get around it.

Use case is the following: I have an std::function member variable, and I want
that member to be able to capture `this`.

Using a strong reference creates a cycle and thus would leak. I know `this` to
always outlive the member, so it is fine to use a weak capture there.

Differential Revision: https://phabricator.services.mozilla.com/D111850
2021-04-14 19:12:02 +00:00

71 lines
1.8 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_StaticAnalysisFunctions_h
#define mozilla_StaticAnalysisFunctions_h
#ifndef __cplusplus
# ifndef bool
# include <stdbool.h>
# endif
# define MOZ_CONSTEXPR
#else // __cplusplus
# include "mozilla/Attributes.h"
# define MOZ_CONSTEXPR constexpr
#endif
/*
* Functions that are used as markers in Gecko code for static analysis. Their
* purpose is to have different AST nodes generated during compile time and to
* match them based on different checkers implemented in build/clang-plugin
*/
#ifdef MOZ_CLANG_PLUGIN
# ifdef __cplusplus
/**
* MOZ_KnownLive - used to opt an argument out of the CanRunScript checker so
* that we don't check it if is a strong ref.
*
* Example:
* canRunScript(MOZ_KnownLive(rawPointer));
*/
template <typename T>
static MOZ_ALWAYS_INLINE T* MOZ_KnownLive(T* ptr) {
return ptr;
}
/**
* Ditto, but for references.
*/
template <typename T>
static MOZ_ALWAYS_INLINE T& MOZ_KnownLive(T& ref) {
return ref;
}
# endif
/**
* MOZ_AssertAssignmentTest - used in MOZ_ASSERT in order to test the possible
* presence of assignment instead of logical comparisons.
*
* Example:
* MOZ_ASSERT(retVal = true);
*/
static MOZ_ALWAYS_INLINE MOZ_CONSTEXPR bool MOZ_AssertAssignmentTest(
bool exprResult) {
return exprResult;
}
# define MOZ_CHECK_ASSERT_ASSIGNMENT(expr) MOZ_AssertAssignmentTest(!!(expr))
#else
# define MOZ_CHECK_ASSERT_ASSIGNMENT(expr) (!!(expr))
# define MOZ_KnownLive(expr) (expr)
#endif /* MOZ_CLANG_PLUGIN */
#endif /* StaticAnalysisFunctions_h */