alexfh added a comment.
In D59135#1458265 <https://reviews.llvm.org/D59135#1458265>, @thorsten-klein
wrote:
> Hello @alexfh ,
> Let me extend your example
>
> $ cat a.cc
> #include "b.h"
> #include "d.h"
> int main(){check(nullptr);}
> $ cat b.h
> #include "c.h"
> inline void b() { c(/*y=*/42); }
> $ cat c.h
> void c(int x);
> $ cat d.h
> inline char* check(char* buffer)
> {
> *buffer++=1; // Should be clang-analyzer-core.NullDereference
> return buffer;
> }
>
>
>
> Now an additional warning is found and shown (=not suppressed):
>
> $ clang-tidy -checks=-*,clang-*,bugprone-argument-comment a.cc --
> 2 warnings generated.
> /home/default/Temp/clang-tidy-test/d.h:3:11: warning: Dereference of null
> pointer [clang-analyzer-core.NullDereference]
> *buffer++=1; // Should be clang-analyzer-core.NullDereference
> ^
> /home/default/Temp/clang-tidy-test/a.cc:3:12: note: Calling 'check'
> int main(){check(0);}
> ^
> /home/default/Temp/clang-tidy-test/d.h:3:3: note: Null pointer value stored
> to 'buffer'
> *buffer++=1; // Should be clang-analyzer-core.NullDereference
> ^
> /home/default/Temp/clang-tidy-test/d.h:3:11: note: Dereference of null
> pointer
> *buffer++=1; // Should be clang-analyzer-core.NullDereference
> ^
> Suppressed 1 warnings (1 in non-user code).
> Use -header-filter=.* to display errors from all non-system headers. Use
> -system-headers to display errors from system headers as well.
>
The behavior in the case above seems to be correct. The null pointer
dereference is happening in d.h:3:11, which is not included into the default
header-filter (which is empty == no headers are considered "interesting" on
their own). However, the (possible) cause of the problem is in a.cc:3:12, which
is considered "interesting". Thus the whole diagnostic with all notes attached
to it is displayed to the user.
The general rule is: a warning (together with all of its notes) is displayed if
its location or location of any of it's notes is inside a the main file or a
(non-system, unless -system-headers option is present) header matching the
regex configured via the -header-filter option. The -line-filter works in a
very similar way, but the whole main file is not whitelisted by default, only
the ranges of lines in it that are parts of the -line-filter.
> **How can I use -header-filter now?**
This depends on what you're trying to achieve.
> With -header-filter=b.h clang-tidy shows both warnings:
This aligns well with the logic I described above.
> With -header-filter=c.h clang-tidy shows both warnings:
Same here: the bugprone-argument-comment warning is shown due to the
-header-filter=c.h option. The clang-analyzer-core.NullDereference will be
shown regardless of the -header-filter value, because it is related to the main
file.
> With -header-filter=c.h clang-tidy shows both warnings:
It looks like you wanted to say that with -header-filter=d.h only the
clang-analyzer-core.NullDereference warning is shown. Seems correct. See above.
> How can I suppress warning for my header file //**d.h**// so that only
> warning from //**b.h**// is shown?
The warning in d.h is related to the main file (since it has a note in the main
file). It will be displayed regardless of the -header-filter. This is by design.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59135/new/
https://reviews.llvm.org/D59135
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