* gdb incremental read missing header files
@ 2015-01-21 20:48 David Taylor
0 siblings, 0 replies; only message in thread
From: David Taylor @ 2015-01-21 20:48 UTC (permalink / raw)
To: gdb
When using DWARF debug information, and incremental (the default)
reading of debug information, GDB will oftentimes miss header files
until the user visits a file that includes, directly or indirectly, the
header file.
Example (the following is a constructed example; the actual problem is
seen when building our embedded kernel that does not include system
header files):
main.c:
-------
extern void print_hello (void);
int
main (int argc, char *argv[])
{
print_hello ();
return (0);
}
hello.c:
--------
#include <stdio.h>
void
print_hello (void)
{
printf ("Hello, world\n");
}
build thusly:
-------------
gcc -c -g3 -O3 main.c
gcc -c -g3 -O3 hello.c
gcc -o missing-headers main.o hello.o
Run gdb:
--------
gdb missing-headers
At prompt, type:
----------------
(gdb) info sources
Source files for which symbols have been read in:
/emc/dtaylor/bugs/missing-headers/main.c
Source files for which symbols will be read in on demand:
/usr/include/bits/stdio2.h, /emc/dtaylor/bugs/missing-headers/hello.c
(gdb) list features.h:1
No source file named features.h.
(gdb) list hello.c:1
1 #include <stdio.h>
2
3 void
4 print_hello (void)
5 {
6 printf ("Hello, world\n");
7 }
(gdb) info sources
Source files for which symbols have been read in:
/emc/dtaylor/bugs/missing-headers/hello.c, /usr/include/stdio.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-64.h,
/usr/lib/gcc/x86_64-linux-gnu/4.4/include/stddef.h, /usr/include/bits/types.h,
/usr/include/bits/typesizes.h, /usr/include/libio.h, /usr/include/_G_config.h,
/usr/include/wchar.h, /usr/lib/gcc/x86_64-linux-gnu/4.4/include/stdarg.h,
/usr/include/bits/stdio_lim.h, /usr/include/bits/sys_errlist.h,
/usr/include/bits/stdio.h, /usr/include/bits/stdio2.h,
/emc/dtaylor/bugs/missing-headers/main.c
Source files for which symbols will be read in on demand:
/usr/include/bits/stdio2.h
(gdb) list features.h:1
1 /* Copyright (C) 1991-1993,1995-2007,2009,2010 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
(gdb)
I did this with the 7.9 pre-release (to make sure that there wasn't a
bug fix that I missed), but the same problem occurs in 7.8 and earlier
versions.
By contrast, with STABS most (all?) headers are found without the need
to first 'visit' a file thst includes them.
The above was done on an x86-64 GNU/Linux system, though I doubt that
that matters much to duplicating the problem.
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