C++

This year's Winter ISO C++ Standard Committee meeting was held in March in Jacksonville, Florida. A number of larger features were discussed. This report focuses on the topics of interest to the Concurrency and Parallelism Study Group (SG1).

Following is a trip report from the March 2018 ISO C++ Meeting (Core Language) held in Jacksonville, Florida. This meeting was mostly about new features for C++20, particularly when and how to merge Technical Specifications into the draft standard.

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This blog is part of a series covering the latest changes and improvements in the Spring 2018 GNU Toolchain Update and components that make up this Toolchain. Apart from the announcement of new releases, however, the features described here are at the bleeding edge of software development in the tools.

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Get a list of recommended build flags for compiling your C or C++ programs with the GCC compiler. Do you know which build flags you need to specify in order to obtain the same level of security hardening that GNU/Linux distributions such as Fedora and Red Hat Enterprise Linux use?

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This article summarizes work that was done to make GCC 8 more usable by providing easier to understand warning and error messages. Many of these improvements will help you quickly recognize those common silly mistakes.

Several Red Hat engineers attended the JTC1/SC22/WG21 C++ Standards Committee meetings in November 2017. This post focuses on the sessions of SG1, the study group on parallelism and concurrency. SG1 had a full schedule as usual, with Executors, Futures, and deferred reclamation mechanisms (e.g., RCU) being major discussion topics. We also started to track the state of proposals and topics we will need to discuss in a publicly accessible bug tracker. I have argued in the past that SG1 should...

GDB has evolved in the last several years to provide a Python API. This series of articles will look at how a user can program GDB with the API and will also take an in-depth look at several features of that API. But, before we begin, a small history lesson is needed and a look at just why an API was needed. Why an API? The humble debugger. We've all used one at some point in our careers, sometimes with...

Several Red Hat engineers attended the JTC1/SC22/WG21 C++ Standards Committee meetings in July 2017. This post focuses on the sessions of SG1, the study group on parallelism and concurrency. We discussed several synchronization-related proposals, improvements for futures, and, of course, executors. Also, I proposed a few steps that the SG1 community could take to get more efficient in how it conducts its work, which are all inspired by how successful open source projects work. Most of the proposals we discussed...

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Surely, you too have been frustrated, while single-stepping optimized programs in symbolic debuggers, by the Brownian motion in the source code, and by never being sure, when you reach a certain source line (if you can reach it at all), whether or not earlier lines have taken effect. Our frustration is about to be significantly alleviated, thanks to two new pieces of technology about to be contributed to the GNU toolchain. Statement Frontier Notes are stable markers of source locations...

I attended the recent Issaquah and Kona ISO C++ standards meetings, representing Red Hat and the GCC project, and helping to complete the C++17 standard. As usual, I spent the majority of my time in the Library Working Group (LWG) sessions, but also took part in a subgroup focusing on the Filesystem library, more on that below. Following the National Body (NB) ballot on the C++17 draft, the LWG had a huge number of comments to process. Some issues were...

The March/April C++ meeting was back in Kona, Hawaii again, only a year and a half after the last Kona meeting. As usual, Red Hat sent three of us to the meeting: Jonathan Wakely, Torvald Riegel, and me. The headline from the meeting was voting to submit C++17 for approval by the national bodies. There wasn't really any significant resistance. There was one new feature added in the final draft, namely std::byte, which was expected to go in at the...

Several Red Hat engineers attended the JTC1/SC22/WG21 C++ Standards Committee meetings in March 2017. This post focuses on the sessions of SG1, the study group on parallelism and concurrency. The major topics of work of the week were (1) further polishing of the parallel algorithms in the C++17 draft, (2) making progress on the executors proposal (which provides mechanisms to control how parallel work is executed, for example on which resources), and (3) continuing work on proposals targeting the Concurrency...

In this article, I want to provide some background details about our recently developed demonstration video - “ Running Game of Life across multiple architectures with Red Hat Enterprise Linux “. This video shows the Game of Life running in a heterogeneous environment using three 64-bit hardware architectures: aarch64 (ARM v8-A), ppc64le (IBM Power little endian) and x86_64 (Intel Xeon). If you are not familiar with the rules of this cellular automaton, they are worth checking out via the reference...

A few years back (2013-2016) I was working as a C++ Software Development Engineer at Intel on a monolithic product with a backend written in C++ and a web frontend written in Java. The product was shipped complete with hardware and as a VMware image. Internally we kept ISO CD images on a shared server for every released or QA approved version of the product. Built into the product was a very clever issue reporting mechanism that allowed us, developers...

Today, we are announcing the general availability of Red Hat Software Collections 2.4, Red Hat’s latest set of open source web development tools, dynamic languages, and databases. We are also announcing Red Hat Developer Toolset 6.1, which helps to streamline application development on Red Hat Enterprise Linux by giving developers access to some of the latest, stable open source C and C++ compilers and complementary development tools. New language additions to Red Hat Software Collections 2.4 include: Nginx 1.10 Node.js...

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The problem C/C++ libraries expect to be able to change the internal implementation details of opaque data types from release to release since such a change has no external ABI consequences. If an opaque data type is placed in process-shared memory (when allowed by the standard) and shared with multiple processes, each process must ensure they are using exactly the same version of the library or they could fail in unexpected ways during library upgrades. The placement of opaque data...

(See this article to install GCC 7 on Red Hat Enterprise Linux.) In C and C++, the cases of a switch statement are in fact labels, and the switch is essentially a go to that jumps to the desired label. Since labels do not change the flow of control, one case block falls through to the following case block, unless terminated by a return, a break, a no return call or similar. In the example below, " case 1" falls...

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In 2016, many improvements happened in the ABI static analysis framework that is Libabigail. In this article we'll present how fedabipkgdiff, a new Libabigail tool can help Fedora users, developers and others to analyze ABI changes of libraries carried by packages of the distribution. Introduction As many of you already know, the engine used to build RPM packages in the Fedora build system is named Koji. Thus, one can get Fedora RPMs from Koji using a web browser. In that...

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Introduction GCC has a rich set of features designed to help detect many kinds of programming errors. Of particular interest are those that corrupt the memory of a running program and, in some cases, makes it vulnerable to security threats. Since 2006, GCC has provided a solution to detect and prevent a subset of buffer overflows in C and C++ programs. Although it is based on compiler technology, it's best known under the name Fortify Source derived from the synonymous...

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The next release of the GNU Compiler Collection, GCC 7, is fast approaching, so in this post, I'm going to talk about work I've done to make GCC more reliable GCC has a large test suite: when I test a patch, roughly 330,000 tests are run, covering various aspects of the compiler, such as: handling valid and invalid syntax in the front-ends verifying that optimizations passes are run verifying that the resulting code runs correctly verifying that the debugger can...

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This article describes the steps required to add buffer overflow protection to string functions. As a real-world example, we use the strlcpy function, which is implemented in the libbsd library on some GNU/Linux systems. This kind of buffer overflow protection uses a GNU Compiler Collection (GCC) feature for array size tracking (“source fortification”), accessed through the __builtin_object_size GCC built-in function. In general, these checks are added in a size-checking wrapper function around the original (wrapped) function, which is strlcpy in...

(Part 2)The GNU Toolchain is a collection of programming tools produced by the GNU Project. The tools are often packaged together due to their common use for developing software applications, operating systems, and low level software for embedded systems.

Cross language development in one project In this tutorial style article I'll discuss how to configure Eclipse for Java Native Interface (JNI) development based on a sample project that you can copy and modify. I.e, you can have a single project that can be both Java and C at the same time, and support a full code navigation and debugging of both languages. This article is focused on the configuration of Eclipse rather than explaining JNI itself, however there are...

GDB relies on libcc1's GCC and GDB plugins to implement the " compile code" feature, now extended to support the C++ language. The Compile and Execute machinery enables GDB users to compile and execute code snippets within the context of an existing process. This allows users to perform inspection and modification of the program state using the target language well beyond the feature set historically exposed by symbolic debuggers. Almost anything that can be expressed in C, and now also...

The GNU Toolchain is a collection of programming tools produced by the GNU Project. The tools are often packaged together due to their common use for developing software applications, operating systems, and low level software for embedded systems.

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