22b4470f2a
Update all links to C++ Core Guidelines to `e49158a`.
Refresh done using the following script and some manual edits:
db76e34e74/personal/fred-tingaud/rspec/refresh-cppcoreguidelines.py
When re-using this script, be mindful that:
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Co-authored-by: Marco Borgeaud <marco.borgeaud@sonarsource.com>
74 lines
2.2 KiB
Plaintext
74 lines
2.2 KiB
Plaintext
== Why is this an issue?
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It is tempting to treat function-like macros as functions, but the two things work differently. For instance, the use of functions offers parameter type-checking, while the use of macros does not. Additionally, with macros, there is the potential for a macro to be evaluated multiple times. In general, functions offer a safer, more robust mechanism than function-like macros, and that safety usually outweighs the speed advantages offered by macros. Therefore functions should be used instead when possible.
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=== Noncompliant code example
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[source,cpp]
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----
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#define CUBE (X) ((X) * (X) * (X)) // Noncompliant
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void func(void) {
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int i = 2;
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int a = CUBE(++i); // Noncompliant. Expands to: int a = ((++i) * (++i) * (++i))
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// ...
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}
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----
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=== Compliant solution
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[source,cpp]
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----
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inline int cube(int i) {
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return i * i * i;
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}
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void func(void) {
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int i = 2;
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int a = cube(++i); // yields 27
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// ...
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}
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----
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== Resources
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* MISRA C:2004, 19.7 - A function should be used in preference to a function-like macro.
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* MISRA {cpp}:2008, 16-0-4 - Function-like macros shall not be defined.
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* MISRA C:2012, Dir. 4.9 - A function should be used in preference to a function-like macro where they are interchangeable
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* https://wiki.sei.cmu.edu/confluence/x/INcxBQ[CERT, PRE00-C.] - Prefer inline or static functions to function-like macros
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* {cpp} Core Guidelines - https://github.com/isocpp/CppCoreGuidelines/blob/e49158a/CppCoreGuidelines.md#es31-dont-use-macros-for-constants-or-functions[ES.31: Don't use macros for constants or "functions"]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Use an inline or static function instead.
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'''
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== Comments And Links
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(visible only on this page)
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=== is related to: S962
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=== is related to: S971
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=== on 19 Sep 2014, 13:46:13 Freddy Mallet wrote:
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@Ann, I would append the following MISRA explanations to the description :
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____
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While macros can provide a speed advantage over functions, functions provide a safer and more robust mechanism. This is particularly true with respect to the type checking of parameters, and the problem of function-like macros potentially evaluating parameters multiple times.
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____
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endif::env-github,rspecator-view[]
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