From 40f55f699811285d947dd02e8a5ae906a40f1290 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 14 Mar 2022 15:56:53 +0100 Subject: [PATCH] docs: document we use C11 with GNU extensions now Follow-up for: #22711 --- docs/CODING_STYLE.md | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/docs/CODING_STYLE.md b/docs/CODING_STYLE.md index a808e649b98..dbbf5ae23bc 100644 --- a/docs/CODING_STYLE.md +++ b/docs/CODING_STYLE.md @@ -81,6 +81,19 @@ SPDX-License-Identifier: LGPL-2.1-or-later ## Code Organization and Semantics +- For our codebase we intend to use ISO C11 *with* GNU extensions (aka + "gnu11"). Public APIs (i.e. those we expose via `libsystemd.so` + i.e. `systemd/sd-*.h`) should only use ISO C89 however (with a very limited + set of conservative and common extensions, such as fixed size integer types + from ``), so that we don't force consuming programs into C11 + mode. (This discrepancy in particular means one thing: internally we use C99 + `bool` booleans, externally C89-compatible `int` booleans which generally + have different size in memory and slightly different semantics, also see + below.) Both for internal and external code it's OK to use even newer + features and GCC extension than "gnu11", as long as there's reasonable + fallback #ifdeffery in place to ensure compatibility is retained with older + compilers. + - Please name structures in `PascalCase` (with exceptions, such as public API structs), variables and functions in `snake_case`. @@ -491,7 +504,8 @@ SPDX-License-Identifier: LGPL-2.1-or-later - Use the bool type for booleans, not integers. One exception: in public headers (i.e those in `src/systemd/sd-*.h`) use integers after all, as `bool` - is C99 and in our public APIs we try to stick to C89 (with a few extensions). + is C99 and in our public APIs we try to stick to C89 (with a few extensions; + also see above). ## Deadlocks -- 2.47.3