regarding header files

[Varun Tewari]

Hello people,
Hope you are all doing good.

I was eager to know, if there's a way to tell gcc to display the full path of header file that's getting included while compiling a code.
I mean, suppose we are building a relatively big codebase, and you hitting multiple declaration error. U are able to figure out which files are causing this, but if you want to figure how these files are getting included in your code, even tough you have been careful enough to ensure such things doesn't happen, still?

Any inputs?

 

[Les Cargill]

Hello people,
Hope you are all doing good.

I was eager to know, if there's a way to tell gcc to display the full path of header file that's getting included while compiling a code.
I mean, suppose we are building a relatively big codebase, and you hitting multiple declaration error. U are able to figure out which files are causing this, but if you want to figure how these files are getting included in your code, even tough you have been careful enough to ensure such things doesn't happen, still?

Any inputs?

Look to the -M option for most toolchains.

 

[James Kuyper]

Hello people,
Hope you are all doing good.

I was eager to know, if there's a way to tell gcc to display the full path of header file that's getting included while compiling a code.
I mean, suppose we are building a relatively big codebase, and you hitting multiple declaration error. U are able to figure out which files are causing this, but if you want to figure how these files are getting included in your code, even tough you have been careful enough to ensure such things doesn't happen, still?

If you use the -E option, gcc will create a pre-processed file
containing #line directives indicating where each section of
pre-processed code came from. Tracing backwards from the point where the
problem occurred, you can determine precisely how it got #included.


However, in my recent experience, I haven't found that necessary - gcc
usually includes the needed information in the warning message itself.
This may be a side-effect of one of the warning options I have turned on
- I normally use:-std=c99 -pedantic -Wall -Wpointer-arith -Wcast-align
-Wstrict-prototypes -Wmissing-prototypes.

Here's an example:

In file included from
/MODAPSint/SDPToolkit/SDPTK5.2.16v1.00_f90/include/CUC/odldef.h:462,
from
/MODAPSint/SDPToolkit/SDPTK5.2.16v1.00_f90/include/PGS_MET_Prototypes.h:32,
from
/MODAPSint/SDPToolkit/SDPTK5.2.16v1.00_f90/include/PGS_MET.h:619,
from /L1A/COMMON/MAPI/h/mapi.h:57,
from GEO_product.h:96,
from GEO_parameters.h:5,
from GEO_earth.h:106,
from GEO_write_input_metadata.c:2:
/MODAPSint/SDPToolkit/SDPTK5.2.16v1.00_f90/include/CUC/odldef_prototypes.h:36:
warning: function declaration isn’t a prototype

 

[Varun Tewari]

ok, i will try this.Thnx

 

[Varun Tewari]

Thnx. This helped.

 

[Lucas Pesenti]

Hello people,
Hope you are all doing good.

I was eager to know, if there's a way to tell gcc to display the full path
of header file that's getting included while compiling a code.
I mean, suppose we are building a relatively big codebase, and you hitting
multiple declaration error. U are able to figure out which files are causing
this, but if you want to figure how these files are getting included in your
code, even tough you have been careful enough to ensure such things doesn't
happen, still?

Any inputs?

If you want to have the dependencies of the main source file, you should
indeed use the "-M" option of gcc. Here is an output example (gcc -M main.c
f.c > a.txt), for the following program.

/* main.c */
#include "f.h"
int main(void) { return f(); }

/* f.c */
#include <stdlib.h>
int f(void) { return EXIT_SUCCESS }

/* f.h */
int f(void);

/* a.txt */
main.o: main.c f.h
f.o: f.c /usr/include/stdlib.h /usr/include/features.h \
/usr/include/bits/predefs.h /usr/include/sys/cdefs.h \
/usr/include/bits/wordsize.h /usr/include/gnu/stubs.h \
/usr/include/gnu/stubs-32.h \
/usr/lib/gcc/i686-linux-gnu/4.4.5/include/stddef.h \
/usr/include/bits/waitflags.h /usr/include/bits/waitstatus.h \
/usr/include/endian.h /usr/include/bits/endian.h \
/usr/include/bits/byteswap.h /usr/include/sys/types.h \
/usr/include/bits/types.h /usr/include/bits/typesizes.h \
/usr/include/time.h /usr/include/sys/select.h /usr/include/bits/select.h \
/usr/include/bits/sigset.h /usr/include/bits/time.h \
/usr/include/sys/sysmacros.h /usr/include/bits/pthreadtypes.h \
/usr/include/alloca.h

There are some variants, such as "-MM" (do not mention header files that are
found in system header directories). Besides, you can consider to set an
environment variable, "DEPENDENCIES_OUTPUT", which is equal to the
combination
of the options "-MM" and "-MF".

Look at the "Preprocessor options" from the GCC documentation to have more
information.

Hope this helps.
L.P.