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| -rw-r--r-- | doc/manual.cli | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/doc/manual.cli b/doc/manual.cli index 46181ef..3318044 100644 --- a/doc/manual.cli +++ b/doc/manual.cli @@ -6808,6 +6808,25 @@ particular, this suppresses compiler warnings in such external headers (\c{/external:W0} is automatically added unless a custom \c{/external:Wn} is specified). +\N|While the aim of this functionality is to control warnings in external +libraries, the underlying mechanisms currently provided by compilers have +undesirable side effects. In particular, \c{-isystem} paths are searched after +\c{-I} so translating \c{-I} to \c{-isystem} alters the search order. This +should normally be harmless when using a development build of a library but +may result in a change of semantics for installed libraries. Also, marking the +search path as system has additional (to warning suppression) effects, see +\l{https://gcc.gnu.org/onlinedocs/cpp/System-Headers.html System Headers} in +the GCC documentation for details. + +Another issue is warnings in template instantiations. Each such warning could +be either due to a (potential) issue in the template itself or due to the +template arguments we are instantiating it with. By default, all such warnings +are suppressed and there is currently no way to change this with GCC/Clang +\c{-isystem}. While MSVC provides \c{/external:templates-}, it cannot be +applied on the library by library basis, only globally for the entire +compilation. See MSVC \c{/external:templates-} documentation for more +background on this issue.| + \N|In the future this functionality will be extended to side-building BMIs for external module interfaces and header units.| |