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[clang-tidy]avoid bugprone-unused-return-value false positive for function with the same prefix as the default argument #84333

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Mar 8, 2024
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[clang-tidy]avoid bugprone-unused-return-value false positive for function with the same prefix as the default argument #84333

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aaa9ea1
[clang-tidy]avoid bugprone-unused-return-value false negative for fun…
HerrCai0907 Mar 7, 2024
e9505c3
update docs
HerrCai0907 Mar 8, 2024
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184 changes: 92 additions & 92 deletions clang-tools-extra/clang-tidy/bugprone/UnusedReturnValueCheck.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,102 +34,102 @@ UnusedReturnValueCheck::UnusedReturnValueCheck(llvm::StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
CheckedFunctions(utils::options::parseStringList(
Options.get("CheckedFunctions", "::std::async;"
"::std::launder;"
"::std::remove;"
"::std::remove_if;"
"::std::unique;"
"::std::unique_ptr::release;"
"::std::basic_string::empty;"
"::std::vector::empty;"
"::std::back_inserter;"
"::std::distance;"
"::std::find;"
"::std::find_if;"
"::std::inserter;"
"::std::lower_bound;"
"::std::make_pair;"
"::std::map::count;"
"::std::map::find;"
"::std::map::lower_bound;"
"::std::multimap::equal_range;"
"::std::multimap::upper_bound;"
"::std::set::count;"
"::std::set::find;"
"::std::setfill;"
"::std::setprecision;"
"::std::setw;"
"::std::upper_bound;"
"::std::vector::at;"
Options.get("CheckedFunctions", "::std::async$;"
"::std::launder$;"
"::std::remove$;"
"::std::remove_if$;"
"::std::unique$;"
"::std::unique_ptr::release$;"
"::std::basic_string::empty$;"
"::std::vector::empty$;"
"::std::back_inserter$;"
"::std::distance$;"
"::std::find$;"
"::std::find_if$;"
"::std::inserter$;"
"::std::lower_bound$;"
"::std::make_pair$;"
"::std::map::count$;"
"::std::map::find$;"
"::std::map::lower_bound$;"
"::std::multimap::equal_range$;"
"::std::multimap::upper_bound$;"
"::std::set::count$;"
"::std::set::find$;"
"::std::setfill$;"
"::std::setprecision$;"
"::std::setw$;"
"::std::upper_bound$;"
"::std::vector::at$;"
// C standard library
"::bsearch;"
"::ferror;"
"::feof;"
"::isalnum;"
"::isalpha;"
"::isblank;"
"::iscntrl;"
"::isdigit;"
"::isgraph;"
"::islower;"
"::isprint;"
"::ispunct;"
"::isspace;"
"::isupper;"
"::iswalnum;"
"::iswprint;"
"::iswspace;"
"::isxdigit;"
"::memchr;"
"::memcmp;"
"::strcmp;"
"::strcoll;"
"::strncmp;"
"::strpbrk;"
"::strrchr;"
"::strspn;"
"::strstr;"
"::wcscmp;"
"::bsearch$;"
"::ferror$;"
"::feof$;"
"::isalnum$;"
"::isalpha$;"
"::isblank$;"
"::iscntrl$;"
"::isdigit$;"
"::isgraph$;"
"::islower$;"
"::isprint$;"
"::ispunct$;"
"::isspace$;"
"::isupper$;"
"::iswalnum$;"
"::iswprint$;"
"::iswspace$;"
"::isxdigit$;"
"::memchr$;"
"::memcmp$;"
"::strcmp$;"
"::strcoll$;"
"::strncmp$;"
"::strpbrk$;"
"::strrchr$;"
"::strspn$;"
"::strstr$;"
"::wcscmp$;"
// POSIX
"::access;"
"::bind;"
"::connect;"
"::difftime;"
"::dlsym;"
"::fnmatch;"
"::getaddrinfo;"
"::getopt;"
"::htonl;"
"::htons;"
"::iconv_open;"
"::inet_addr;"
"::isascii;"
"::isatty;"
"::mmap;"
"::newlocale;"
"::openat;"
"::pathconf;"
"::pthread_equal;"
"::pthread_getspecific;"
"::pthread_mutex_trylock;"
"::readdir;"
"::readlink;"
"::recvmsg;"
"::regexec;"
"::scandir;"
"::semget;"
"::setjmp;"
"::shm_open;"
"::shmget;"
"::sigismember;"
"::strcasecmp;"
"::strsignal;"
"::access$;"
"::bind$;"
"::connect$;"
"::difftime$;"
"::dlsym$;"
"::fnmatch$;"
"::getaddrinfo$;"
"::getopt$;"
"::htonl$;"
"::htons$;"
"::iconv_open$;"
"::inet_addr$;"
"::isascii$;"
"::isatty$;"
"::mmap$;"
"::newlocale$;"
"::openat$;"
"::pathconf$;"
"::pthread_equal$;"
"::pthread_getspecific$;"
"::pthread_mutex_trylock$;"
"::readdir$;"
"::readlink$;"
"::recvmsg$;"
"::regexec$;"
"::scandir$;"
"::semget$;"
"::setjmp$;"
"::shm_open$;"
"::shmget$;"
"::sigismember$;"
"::strcasecmp$;"
"::strsignal$;"
"::ttyname"))),
CheckedReturnTypes(utils::options::parseStringList(
Options.get("CheckedReturnTypes", "::std::error_code;"
"::std::error_condition;"
"::std::errc;"
"::std::expected;"
Options.get("CheckedReturnTypes", "::std::error_code$;"
"::std::error_condition$;"
"::std::errc$;"
"::std::expected$;"
"::boost::system::error_code"))),
AllowCastToVoid(Options.get("AllowCastToVoid", false)) {}

Expand Down
4 changes: 3 additions & 1 deletion clang-tools-extra/docs/ReleaseNotes.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -152,7 +152,9 @@ Changes in existing checks

- Improved :doc:`bugprone-unused-return-value
<clang-tidy/checks/bugprone/unused-return-value>` check by updating the
parameter `CheckedFunctions` to support regexp.
parameter `CheckedFunctions` to support regexp and avoiding false postive for
function with the same prefix as the default argument, e.g. ``std::unique_ptr``
and ``std::unique``.

- Improved :doc:`bugprone-use-after-move
<clang-tidy/checks/bugprone/use-after-move>` check to also handle
Expand Down
33 changes: 17 additions & 16 deletions clang-tools-extra/docs/clang-tidy/checks/bugprone/unused-return-value.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -14,22 +14,23 @@ Options
This parameter supports regexp. The function is checked if the name
and scope matches, with any arguments.
By default the following functions are checked:
``std::async, std::launder, std::remove, std::remove_if, std::unique,
std::unique_ptr::release, std::basic_string::empty, std::vector::empty,
std::back_inserter, std::distance, std::find, std::find_if, std::inserter,
std::lower_bound, std::make_pair, std::map::count, std::map::find,
std::map::lower_bound, std::multimap::equal_range,
std::multimap::upper_bound, std::set::count, std::set::find, std::setfill,
std::setprecision, std::setw, std::upper_bound, std::vector::at,
bsearch, ferror, feof, isalnum, isalpha, isblank, iscntrl, isdigit, isgraph,
islower, isprint, ispunct, isspace, isupper, iswalnum, iswprint, iswspace,
isxdigit, memchr, memcmp, strcmp, strcoll, strncmp, strpbrk, strrchr,
strspn, strstr, wcscmp, access, bind, connect, difftime, dlsym, fnmatch,
getaddrinfo, getopt, htonl, htons, iconv_open, inet_addr, isascii, isatty,
mmap, newlocale, openat, pathconf, pthread_equal, pthread_getspecific,
pthread_mutex_trylock, readdir, readlink, recvmsg, regexec, scandir,
semget, setjmp, shm_open, shmget, sigismember, strcasecmp, strsignal,
ttyname``
``::std::async$, ::std::launder$, ::std::remove$, ::std::remove_if$, ::std::unique$,
::std::unique_ptr::release$, ::std::basic_string::empty$, ::std::vector::empty$,
::std::back_inserter$, ::std::distance$, ::std::find$, ::std::find_if$, ::std::inserter$,
::std::lower_bound$, ::std::make_pair$, ::std::map::count$, ::std::map::find$,
::std::map::lower_bound$, ::std::multimap::equal_range$, ::std::multimap::upper_bound$,
::std::set::count$, ::std::set::find$, ::std::setfill$, ::std::setprecision$,
::std::setw$, ::std::upper_bound$, ::std::vector::at$, ::bsearch$, ::ferror$,
::feof$, ::isalnum$, ::isalpha$, ::isblank$, ::iscntrl$, ::isdigit$, ::isgraph$,
::islower$, ::isprint$, ::ispunct$, ::isspace$, ::isupper$, ::iswalnum$, ::iswprint$,
::iswspace$, ::isxdigit$, ::memchr$, ::memcmp$, ::strcmp$, ::strcoll$, ::strncmp$,
::strpbrk$, ::strrchr$, ::strspn$, ::strstr$, ::wcscmp$, ::access$, ::bind$,
::connect$, ::difftime$, ::dlsym$, ::fnmatch$, ::getaddrinfo$, ::getopt$,
::htonl$, ::htons$, ::iconv_open$, ::inet_addr$, isascii$, isatty$, ::mmap$,
::newlocale$, ::openat$, ::pathconf$, ::pthread_equal$, ::pthread_getspecific$,
::pthread_mutex_trylock$, ::readdir$, ::readlink$, ::recvmsg$, ::regexec$, ::scandir$,
::semget$, ::setjmp$, ::shm_open$, ::shmget$, ::sigismember$, ::strcasecmp$, ::strsignal$,
::ttyname$``

- ``std::async()``. Not using the return value makes the call synchronous.
- ``std::launder()``. Not using the return value usually means that the
Expand Down
14 changes: 14 additions & 0 deletions clang-tools-extra/test/clang-tidy/checkers/bugprone/unused-return-value.cpp
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Expand Up @@ -30,6 +30,11 @@ struct default_delete;

template <typename T, typename Deleter = std::default_delete<T>>
struct unique_ptr {
unique_ptr();
unique_ptr(unique_ptr const&);
unique_ptr(unique_ptr &&);
unique_ptr& operator=(unique_ptr const&);
unique_ptr& operator=(unique_ptr &&);
T *release() noexcept;
};

Expand Down Expand Up @@ -254,3 +259,12 @@ void noWarning() {
({ std::async(increment, 42); });
auto StmtExprRetval = ({ std::async(increment, 42); });
}

namespace gh84314 {

extern std::unique_ptr<int> alloc();
void f1(std::unique_ptr<int> &foo) {
foo = alloc();
}

} // namespace gh84314