C++ – ctags does not parse stdio.h properly

cctagsuclinux

I am trying to use ctags with VIM, and I am a newbie to both. In order to test the extent to which ctags could be useful I decided to put it through a very simple test, namely to parse the headers in /usr/include so that I could autocomplete some very basic functions.

When I run the command

 ctags  --c++-kinds=+p --fields=+iaS -f ~/.tags/tags /usr/include/*.h

then the output prints

BUFSIZ  /usr/include/stdio.h    108;"   d
EOF /usr/include/stdio.h    115;"   d
FILE    /usr/include/stdio.h    /^typedef struct _IO_FILE FILE;$/;" t   typeref:struct:_IO_FILE
FSETLOCKING_BYCALLER    /usr/include/stdio_ext.h    /^  FSETLOCKING_BYCALLER$/;"    e   enum:__anon122
FSETLOCKING_BYCALLER    /usr/include/stdio_ext.h    39;"    d
FSETLOCKING_INTERNAL    /usr/include/stdio_ext.h    /^  FSETLOCKING_INTERNAL,$/;"   e   enum:__anon122
FSETLOCKING_INTERNAL    /usr/include/stdio_ext.h    36;"    d
FSETLOCKING_QUERY   /usr/include/stdio_ext.h    /^  FSETLOCKING_QUERY = 0,$/;"  e   enum:__anon122
FSETLOCKING_QUERY   /usr/include/stdio_ext.h    32;"    d
P_tmpdir    /usr/include/stdio.h    128;"   d
SEEK_CUR    /usr/include/stdio.h    122;"   d
SEEK_END    /usr/include/stdio.h    123;"   d
SEEK_SET    /usr/include/stdio.h    121;"   d
_IOFBF  /usr/include/stdio.h    101;"   d
_IOLBF  /usr/include/stdio.h    102;"   d
_IONBF  /usr/include/stdio.h    103;"   d
_IO_STDIO   /usr/include/libio.h    165;"   d
_IO_STDIO_H /usr/include/libio.h    30;"    d
_OLD_STDIO_MAGIC    /usr/include/libio.h    121;"   d
_STDIO_EXT_H    /usr/include/stdio_ext.h    24;"    d
_STDIO_H    /usr/include/stdio.h    27;"    d
_STDIO_USES_IOSTREAM    /usr/include/stdio.h    73;"    d
_VA_LIST_DEFINED    /usr/include/stdio.h    81;"    d
__FILE  /usr/include/stdio.h    /^typedef struct _IO_FILE __FILE;$/;"   t   typeref:struct:_IO_FILE
__FILE_defined  /usr/include/stdio.h    57;"    d
____FILE_defined    /usr/include/stdio.h    67;"    d
__need_FILE /usr/include/stdio.h    37;"    d
__need_FILE /usr/include/stdio.h    59;"    d
__need_NULL /usr/include/stdio.h    33;"    d
__need___FILE   /usr/include/stdio.h    38;"    d
__need___FILE   /usr/include/stdio.h    69;"    d
__need_getopt   /usr/include/stdio.h    902;"   d
__need_size_t   /usr/include/stdio.h    32;"    d
__wur   /usr/include/stdio.h    /^            _IO_cookie_io_functions_t __io_funcs) __THROW __wur;$/;"  v
__wur   /usr/include/stdio.h    /^     __THROW __attribute__ ((__format__ (__printf__, 2, 0))) __wur;$/;"   v
__wur   /usr/include/stdio.h    /^     __THROW __attribute__ ((__format__ (__printf__, 2, 3))) __wur;$/;"   v
__wur   /usr/include/stdio.h    /^     __THROW __attribute_malloc__ __wur;$/;"  v
__wur   /usr/include/stdio.h    /^  __THROW __wur;$/;"  v
__wur   /usr/include/stdio.h    /^extern FILE *fdopen (int __fd, __const char *__modes) __THROW __wur;$/;"  v
__wur   /usr/include/stdio.h    /^extern FILE *open_memstream (char **__bufloc, size_t *__sizeloc) __THROW __wur;$/;"   v
__wur   /usr/include/stdio.h    /^extern char *tmpnam (char *__s) __THROW __wur;$/;"    v
__wur   /usr/include/stdio.h    /^extern char *tmpnam_r (char *__s) __THROW __wur;$/;"  v
__wur   /usr/include/stdio.h    /^extern int feof (FILE *__stream) __THROW __wur;$/;"   v
__wur   /usr/include/stdio.h    /^extern int feof_unlocked (FILE *__stream) __THROW __wur;$/;"  v
__wur   /usr/include/stdio.h    /^extern int ferror (FILE *__stream) __THROW __wur;$/;" v
__wur   /usr/include/stdio.h    /^extern int ferror_unlocked (FILE *__stream) __THROW __wur;$/;"    v
__wur   /usr/include/stdio.h    /^extern int fileno (FILE *__stream) __THROW __wur;$/;" v
__wur   /usr/include/stdio.h    /^extern int fileno_unlocked (FILE *__stream) __THROW __wur;$/;"    v
__wur   /usr/include/stdio.h    /^extern int ftrylockfile (FILE *__stream) __THROW __wur;$/;"   v
_flushlbf   /usr/include/stdio_ext.h    /^extern void _flushlbf (void);$/;" p   signature:(void)
cuserid /usr/include/stdio.h    /^extern char *cuserid (char *__s);$/;" p   signature:(char *__s)
dprintf /usr/include/stdio.h    /^extern int dprintf (int __fd, __const char *__restrict __fmt, ...)$/;"    p   signature:(int __fd, __const char *__restrict __fmt, ...)
fclose  /usr/include/stdio.h    /^extern int fclose (FILE *__stream);$/;"   p   signature:(FILE *__stream)
fcloseall   /usr/include/stdio.h    /^extern int fcloseall (void);$/;"  p   signature:(void)
fflush  /usr/include/stdio.h    /^extern int fflush (FILE *__stream);$/;"   p   signature:(FILE *__stream)
fflush_unlocked /usr/include/stdio.h    /^extern int fflush_unlocked (FILE *__stream);$/;"  p   signature:(FILE *__stream)
fgetc   /usr/include/stdio.h    /^extern int fgetc (FILE *__stream);$/;"    p   signature:(FILE *__stream)
fgetc_unlocked  /usr/include/stdio.h    /^extern int fgetc_unlocked (FILE *__stream);$/;"   p   signature:(FILE *__stream)
fgetpos /usr/include/stdio.h    /^extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos);$/;" p   signature:(FILE *__restrict __stream, fpos_t *__restrict __pos)
fgetpos64   /usr/include/stdio.h    /^extern int fgetpos64 (FILE *__restrict __stream, fpos64_t *__restrict __pos);$/;" p   signature:(FILE *__restrict __stream, fpos64_t *__restrict __pos)
fpos64_t    /usr/include/stdio.h    /^typedef _G_fpos64_t fpos64_t;$/;" t
fpos_t  /usr/include/stdio.h    /^typedef _G_fpos_t fpos_t;$/;" t
fprintf /usr/include/stdio.h    /^extern int fprintf (FILE *__restrict __stream,$/;"    p   signature:(FILE *__restrict __stream, __const char *__restrict __format, ...)
fputc   /usr/include/stdio.h    /^extern int fputc (int __c, FILE *__stream);$/;"   p   signature:(int __c, FILE *__stream)
fputc_unlocked  /usr/include/stdio.h    /^extern int fputc_unlocked (int __c, FILE *__stream);$/;"  p   signature:(int __c, FILE *__stream)
fputs   /usr/include/stdio.h    /^extern int fputs (__const char *__restrict __s, FILE *__restrict __stream);$/;"   p   signature:(__const char *__restrict __s, FILE *__restrict __stream)
fputs_unlocked  /usr/include/stdio.h    /^extern int fputs_unlocked (__const char *__restrict __s,$/;"  p   signature:(__const char *__restrict __s, FILE *__restrict __stream)
fscanf  /usr/include/stdio.h    441;"   d
fseek   /usr/include/stdio.h    /^extern int fseek (FILE *__stream, long int __off, int __whence);$/;"  p   signature:(FILE *__stream, long int __off, int __whence)
fseeko  /usr/include/stdio.h    /^extern int fseeko (FILE *__stream, __off_t __off, int __whence);$/;"  p   signature:(FILE *__stream, __off_t __off, int __whence)
fseeko64    /usr/include/stdio.h    /^extern int fseeko64 (FILE *__stream, __off64_t __off, int __whence);$/;"  p   signature:(FILE *__stream, __off64_t __off, int __whence)
fsetpos /usr/include/stdio.h    /^extern int fsetpos (FILE *__stream, __const fpos_t *__pos);$/;"   p   signature:(FILE *__stream, __const fpos_t *__pos)
fsetpos64   /usr/include/stdio.h    /^extern int fsetpos64 (FILE *__stream, __const fpos64_t *__pos);$/;"   p   signature:(FILE *__stream, __const fpos64_t *__pos)
getc    /usr/include/stdio.h    /^extern int getc (FILE *__stream);$/;" p   signature:(FILE *__stream)
getc    /usr/include/stdio.h    527;"   d
getc_unlocked   /usr/include/stdio.h    /^extern int getc_unlocked (FILE *__stream);$/;"    p   signature:(FILE *__stream)
getchar /usr/include/stdio.h    /^extern int getchar (void);$/;"    p   signature:(void)
getchar_unlocked    /usr/include/stdio.h    /^extern int getchar_unlocked (void);$/;"   p   signature:(void)
getw    /usr/include/stdio.h    /^extern int getw (FILE *__stream);$/;" p   signature:(FILE *__stream)
jpeg_stdio_dest /usr/include/jpeglib.h  /^EXTERN(void) jpeg_stdio_dest JPP((j_compress_ptr cinfo, FILE * outfile));$/;" p   signature:(j_compress_ptr cinfo, FILE * outfile)
jpeg_stdio_dest /usr/include/jpeglib.h  841;"   d
jpeg_stdio_src  /usr/include/jpeglib.h  /^EXTERN(void) jpeg_stdio_src JPP((j_decompress_ptr cinfo, FILE * infile));$/;" p   signature:(j_decompress_ptr cinfo, FILE * infile)
jpeg_stdio_src  /usr/include/jpeglib.h  842;"   d
pclose  /usr/include/stdio.h    /^extern int pclose (FILE *__stream);$/;"   p   signature:(FILE *__stream)
perror  /usr/include/stdio.h    /^extern void perror (__const char *__s);$/;"   p   signature:(__const char *__s)
printf  /usr/include/stdio.h    /^extern int printf (__const char *__restrict __format, ...);$/;"   p   signature:(__const char *__restrict __format, ...)
putc    /usr/include/stdio.h    /^extern int putc (int __c, FILE *__stream);$/;"    p   signature:(int __c, FILE *__stream)
putc    /usr/include/stdio.h    569;"   d
putc_unlocked   /usr/include/stdio.h    /^extern int putc_unlocked (int __c, FILE *__stream);$/;"   p   signature:(int __c, FILE *__stream)
putchar /usr/include/stdio.h    /^extern int putchar (int __c);$/;" p   signature:(int __c)
putchar_unlocked    /usr/include/stdio.h    /^extern int putchar_unlocked (int __c);$/;"    p   signature:(int __c)
puts    /usr/include/stdio.h    /^extern int puts (__const char *__s);$/;"  p   signature:(__const char *__s)
putw    /usr/include/stdio.h    /^extern int putw (int __w, FILE *__stream);$/;"    p   signature:(int __w, FILE *__stream)
rewind  /usr/include/stdio.h    /^extern void rewind (FILE *__stream);$/;"  p   signature:(FILE *__stream)
scanf   /usr/include/stdio.h    442;"   d
sscanf  /usr/include/stdio.h    443;"   d
stderr  /usr/include/stdio.h    152;"   d
stdin   /usr/include/stdio.h    150;"   d
stdout  /usr/include/stdio.h    151;"   d
ungetc  /usr/include/stdio.h    /^extern int ungetc (int __c, FILE *__stream);$/;"  p   signature:(int __c, FILE *__stream)
va_list /usr/include/stdio.h    /^typedef _G_va_list va_list;$/;"   t
vdprintf    /usr/include/stdio.h    /^extern int vdprintf (int __fd, __const char *__restrict __fmt,$/;"    p   signature:(int __fd, __const char *__restrict __fmt, _G_va_list __arg)
vfprintf    /usr/include/stdio.h    /^extern int vfprintf (FILE *__restrict __s, __const char *__restrict __format,$/;" p   signature:(FILE *__restrict __s, __const char *__restrict __format, _G_va_list __arg)
vfscanf /usr/include/stdio.h    500;"   d
vprintf /usr/include/stdio.h    /^extern int vprintf (__const char *__restrict __format, _G_va_list __arg);$/;" p   signature:(__const char *__restrict __format, _G_va_list __arg)
vscanf  /usr/include/stdio.h    501;"   d
vsscanf /usr/include/stdio.h    502;"   d

so clearly ctags missed some very obvious functions like fopen, yet it included functions like fclose. Is there some option I am missing when I am parsing with ctags?

Best Answer

Add a -I__wur to your ctags command and you'll get the result you're after. __wur is a macro for __attribute__ ((__warn_unused_result__))

For a more thurough explanation, see:

http://sourceforge.net/mailarchive/message.php?msg_name=48A7FF60.9080609%40sina.com

Related Solutions

C++ – What does the explicit keyword mean

The compiler is allowed to make one implicit conversion to resolve the parameters to a function. What this means is that the compiler can use constructors callable with a single parameter to convert from one type to another in order to get the right type for a parameter.

Here's an example class with a constructor that can be used for implicit conversions:

class Foo
{
public:
  // single parameter constructor, can be used as an implicit conversion
  Foo (int foo) : m_foo (foo) 
  {
  }

  int GetFoo () { return m_foo; }

private:
  int m_foo;
};

Here's a simple function that takes a Foo object:

void DoBar (Foo foo)
{
  int i = foo.GetFoo ();
}

and here's where the DoBar function is called:

int main ()
{
  DoBar (42);
}

The argument is not a Foo object, but an int. However, there exists a constructor for Foo that takes an int so this constructor can be used to convert the parameter to the correct type.

The compiler is allowed to do this once for each parameter.

Prefixing the explicit keyword to the constructor prevents the compiler from using that constructor for implicit conversions. Adding it to the above class will create a compiler error at the function call DoBar (42). It is now necessary to call for conversion explicitly with DoBar (Foo (42))

The reason you might want to do this is to avoid accidental construction that can hide bugs.
Contrived example:

You have a MyString class with a constructor that constructs a string of the given size. You have a function print(const MyString&) (as well as an overload print (char *string)), and you call print(3) (when you actually intended to call print("3")). You expect it to print "3", but it prints an empty string of length 3 instead.

What does “static” mean in C

A static variable inside a function keeps its value between invocations.
A static global variable or a function is "seen" only in the file it's declared in

(1) is the more foreign topic if you're a newbie, so here's an example:

#include <stdio.h>

void foo()
{
    int a = 10;
    static int sa = 10;

    a += 5;
    sa += 5;

    printf("a = %d, sa = %d\n", a, sa);
}


int main()
{
    int i;

    for (i = 0; i < 10; ++i)
        foo();
}

This prints:

a = 15, sa = 15
a = 15, sa = 20
a = 15, sa = 25
a = 15, sa = 30
a = 15, sa = 35
a = 15, sa = 40
a = 15, sa = 45
a = 15, sa = 50
a = 15, sa = 55
a = 15, sa = 60

This is useful for cases where a function needs to keep some state between invocations, and you don't want to use global variables. Beware, however, this feature should be used very sparingly - it makes your code not thread-safe and harder to understand.

(2) Is used widely as an "access control" feature. If you have a .c file implementing some functionality, it usually exposes only a few "public" functions to users. The rest of its functions should be made static, so that the user won't be able to access them. This is encapsulation, a good practice.

Quoting Wikipedia:

In the C programming language, static is used with global variables and functions to set their scope to the containing file. In local variables, static is used to store the variable in the statically allocated memory instead of the automatically allocated memory. While the language does not dictate the implementation of either type of memory, statically allocated memory is typically reserved in data segment of the program at compile time, while the automatically allocated memory is normally implemented as a transient call stack.

And to answer your second question, it's not like in C#.

In C++, however, static is also used to define class attributes (shared between all objects of the same class) and methods. In C there are no classes, so this feature is irrelevant.

Best Answer

Related Solutions

C++ – What does the explicit keyword mean

What does “static” mean in C

Related Topic