From e390f9f618ec694e5327ebe93cdfc0ba89ab5a86 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Sun, 20 Sep 2020 20:28:56 +0300 Subject: Documentation: Adjust guidelines regarding math.h header MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit While libcamera prefers usage of the C standard library headers (xxx.h) over the C++ version (cxxx), we make an exception for cmath as the overloaded versions of the math functions are convenient. Document this, and adjust checkstyle.py accordingly. Signed-off-by: Laurent Pinchart Reviewed-by: Jacopo Mondi Reviewed-by: Niklas Söderlund --- Documentation/coding-style.rst | 14 +++++++++++--- utils/checkstyle.py | 6 +++--- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/Documentation/coding-style.rst b/Documentation/coding-style.rst index 7c56a1b7..8af06d6a 100644 --- a/Documentation/coding-style.rst +++ b/Documentation/coding-style.rst @@ -195,9 +195,17 @@ them, defines C compatibility headers. The former have a name of the form while the later are named . The C++ headers declare names in the std namespace, and may declare the same names in the global namespace. The C compatibility headers declare names in the global namespace, and may declare -the same names in the std namespace. Usage of the C compatibility headers is -strongly preferred. Code shall not rely on the optional declaration of names in -the global or std namespace. +the same names in the std namespace. Code shall not rely on the optional +declaration of names in the global or std namespace. + +Usage of the C compatibility headers is preferred, except for the math.h header. +Where math.h defines separate functions for different argument types (e.g. +abs(int), labs(long int), fabs(double) and fabsf(float)) and requires the +developer to pick the right function, cmath defines overloaded functions +(std::abs(int), std::abs(long int), std::abs(double) and std::abs(float) to let +the compiler select the right function. This avoids potential errors such as +calling abs(int) with a float argument, performing an unwanted implicit integer +conversion. For this reason, cmath is preferred over math.h. Documentation diff --git a/utils/checkstyle.py b/utils/checkstyle.py index b594a19a..d5dc26c0 100755 --- a/utils/checkstyle.py +++ b/utils/checkstyle.py @@ -244,9 +244,9 @@ class IncludeChecker(StyleChecker): patterns = ('*.cpp', '*.h') headers = ('assert', 'ctype', 'errno', 'fenv', 'float', 'inttypes', - 'limits', 'locale', 'math', 'setjmp', 'signal', 'stdarg', - 'stddef', 'stdint', 'stdio', 'stdlib', 'string', 'time', 'uchar', - 'wchar', 'wctype') + 'limits', 'locale', 'setjmp', 'signal', 'stdarg', 'stddef', + 'stdint', 'stdio', 'stdlib', 'string', 'time', 'uchar', 'wchar', + 'wctype') include_regex = re.compile('^#include ') def __init__(self, content): -- cgit v1.2.1