ctags breaks on template instantiations that bitshift in parameters

[focalintent]

FastLED makes pretty extensive use of templates to do a lot of this work. Some of what's done with templates involves creating bitmasks from template parameters as parameters to other templates. Unfortunately, when the ctags parser sees "1<<X" as a template parameter, it eats itself.

This code demonstrates the problem:

template <int PORT_MASK> class controller { 

};

template <int LANES> class myClass { 
  public:
    void useController(controller<(1<<LANES)-1> & controller);    
};

void setup() { myctagstestfunc(); }
void myctagstestfunc() { }
void loop() {}

Because ctags stops parsing, the prototype for myctagstestfunc() is never created, and the dreaded 'myctagstestfun' was not declared in this scope error (as seen in #68)

[masatake]

[yamato@x201]~/var/ctags-github% ./ctags --sort=no -o - foo.cpp
controller  foo.cpp /^template <int PORT_MASK> class controller { $/;"  c   file:
myClass foo.cpp /^template <int LANES> class myClass { $/;" c   file:
setup   foo.cpp /^void setup() { myctagstestfunc(); }$/;"   f
myctagstestfunc foo.cpp /^void myctagstestfunc() { }$/;"    f
loop    foo.cpp /^void loop() {}$/;"    f

This is the expected tags output of this issue?

[focalintent]

Pretty much, yes.

[masatake]

The following commit may fix it.
masatake/ctags@9a7ce23

[focalintent]

Unfortunately - that commit will most likely fail in the case of:

template <int PORT_MASK> class controller { 
};

controller< 1<<8 > aController;

because the code in the commit that you linked to only ignores the <> characters after an = or when inside of ()'s.

So even with your commit - you should still do the one character lookahead to decide whether or not you've got a bit shift happening. Of course, then there's also having conditional expressions as template parameters which would likely trip up both of our fixes.

[focalintent]

Yup - just tried here with

template <int P> class c {};
c< 8 > bVar;
c< 1<<8 > aVar;

and I get:

Xantico:u-ctags dgarcia$ ./ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/x.cpp
ctags: Warning: Unsupported parameter 'T' for "fields" option
bVar    /tmp/x.cpp  /^c< 8 > bVar;$/;"  kind:variable   line:2

aVar does'n't come out - if I add the lookahead/skip in c.c (similar to what's in my pull request in arduino/ctags#7) then I get this output:

template <int P> class c {};
c< 8 > bVar;
c< 1<<8 > aVar;

[focalintent]

universal-ctags/ctags#807 for a fix on universal-ctags

[facchinm]

Fixed by merging arduino/ctags#7