1.\" $OpenBSD: clang-local.1,v 1.11 2017/10/05 15:13:43 jmc Exp $ 2.\" 3.\" Copyright (c) 2016 Pascal Stumpf <pascal@stumpf.co> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.\" 18.Dd $Mdocdate: October 5 2017 $ 19.Dt CLANG-LOCAL 1 20.Os 21.Sh NAME 22.Nm clang-local 23.Nd OpenBSD-specific behavior of LLVM/clang 24.Sh DESCRIPTION 25On 26.Ox , 27the LLVM/clang compiler exhibits the following characteristics: 28.Bl -dash 29.It 30.Nm clang 31does not search under 32.Pa /usr/local 33for include files or libraries: 34as a system compiler, it only searches the system paths by default. 35.It 36.Nm clang 37comes with stack protection enabled by default, equivalent to the 38.Fl fstack-protector-strong 39option on other systems. 40The system will report any violation of the stack protector cookie along 41with the function name via 42.Xr syslog 3 43at 44.Dv LOG_CRIT 45priority. 46.It 47.Nm clang 48will generate PIE code by default, allowing the system to load the resulting 49binary at a random location. 50This behavior can be turned off by passing 51.Fl fno-pie 52to the compiler and 53.Fl nopie 54to the linker. 55.It 56The 57.Fl fstrict-aliasing 58option is turned off by default unless 59.Fl Ofast 60has been selected. 61.It 62.Nm clang 63does not store its version string in objects. 64There is no option to control this. 65.It 66The 67.Fl pg 68flag is an alias of 69.Fl p . 70.It 71.Nm clang 72does not warn for passing pointer arguments or assignment with 73different signedness outside of 74.Fl pedantic . 75This can be 76re-enabled with the 77.Fl Wpointer-sign 78flag. 79.It 80The warning option 81.Fl Waddress-of-packed-member 82is disabled by default. 83.It 84Color diagnostic messages are disabled by default and can be re-enabled with 85.Fl fdiagnostics-color . 86.It 87The 88.Fl fwrapv 89option to treat signed integer overflows as defined is enabled by default to 90prevent dangerous optimizations which could remove security critical overflow 91checks. 92.It 93The 94.Xr malloc 3 , 95.Xr calloc 3 , 96.Xr realloc 3 , 97.Xr strdup 3 , 98.Xr strndup 3 , 99.Xr valloc 3 100and 101.Xr free 3 102builtins are disabled to prevent undesirable optimizations of calls to 103these functions. 104.El 105.Sh SEE ALSO 106.Xr clang 1 107