Ping ?
On Fri, Jan 31, 2014 at 12:47 AM, Prathamesh Kulkarni <bilbotheelffri...@gmail.com> wrote: > Hi, I was wondering if it's a good idea to add -Wheader-guard option > that warns on mismatches between #ifndef and #define lines > in header guard, similar to -Wheader-guard in clang-3.4 ? > (http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html) > > I have implemented patch for -Wheader-guard (please find it attached). > Consider a file having the following format: > #ifndef cmacro (or #if !defined(cmacro) ) > #define dmacro > // rest of the stuff > #endif > > The warning is triggered if the edit distance > (http://en.wikipedia.org/wiki/Levenshtein_distance), between cmacro > and dmacro > is <= max (len(cmacro), len(dmacro)) / 2 > If the edit distance is more than half, I assume that cmacro > and dmacro are "very different", and the intent > was probably not to define header guard (This is what clang does too). > > Example: > #ifndef FOO_H > #define _FOO_H > #endif > > foo.h:1:0: warning: FOO_H used as header guard followed by #define of > different macro [-Wheader-guard] > #ifndef FOO_H > ^ > foo.h:2:0: note: FOO_H is defined here, did you mean _FOO_H ? > #define _FOO_H > ^ > > Warning is not triggered in the following cases: > > 1] The edit distance between #ifndef (or #!defined) macro > and #define macro is > half of maximum length between two macros > > Example: > #ifndef FOO > #define BAR > #endif > > 2] #ifndef and #define are not on consecutive lines (blank lines/ comment > lines > are not ignored). > > 3] dmacro gets undefined > Example: > #ifndef cmacro > #define dmacro > #undef dmacro > #endif > > However the following warning gets generated during the build: > ../../src/libcpp/directives.c: In function 'void > _cpp_pop_buffer(cpp_reader*)': > ../../src/libcpp/directives.c: > 2720:59: warning: 'inc_type' may be used > uninitialized in this function [-Wmaybe-uninitialized] > _cpp_pop_file_buffer (pfile, inc, to_free, inc_type); > ^ > _cpp_pop_buffer(): http://pastebin.com/aLYLnXJa > I have defined inc_type only if inc is not null (ie buffer is file > buffer) in 1st if() > and used it (passed it to _cpp_pop_file_buffer() ), only if inc is not null > in 2nd if(). I guess this warning could be considered harmless ? > How should I should rewrite it to avoid the warning ? > > Thanks and Regards, > Prathamesh
