I created a small dummy program with a dedicated insignificant bug. But gcc throws an error and then core dumps, which is abnormal.
Here is the output: gcc -v -save-temps 1.c >& log.txt Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --enable-checking=release i486-linux-gnu Thread model: posix gcc version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2) /usr/lib/gcc/i486-linux-gnu/4.1.3/cc1 -E -quiet -v 1.c -mtune=generic -fpch-preprocess -o 1.i ignoring nonexistent directory "/usr/local/include/i486-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/i486-linux-gnu/4.1.3/../../../../i486-linux-gnu/include" ignoring nonexistent directory "/usr/include/i486-linux-gnu" #include "..." search starts here: #include <...> search starts here: /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.1.3/include /usr/include End of search list. /usr/lib/gcc/i486-linux-gnu/4.1.3/cc1 -fpreprocessed 1.i -quiet -dumpbase 1.c -mtune=generic -auxbase 1 -version -fstack-protector -fstack-protector -o 1.s GNU C version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2) (i486-linux-gnu) compiled by GNU C version 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2). GGC heuristics: --param ggc-min-expand=47 --param ggc-min-heapsize=31866 Compiler executable checksum: caf034d6752b947185f431aa3e927159 In file included from 3.h:6, from 2.h:6, from 1.h:5, from 1.c:2: 1.h:3: error: redefinition of typedef F1 1.h:3: error: previous declaration of F1 was here In file included from 3.h:6, from 2.h:6, from 1.h:5, from 1.c:2: 1.h:9: error: field a2 has incomplete type In file included from 1.c:2: 1.h:7: error: redefinition of struct f1 gcc: Internal error: Segmentation fault (program cc1) Please submit a full bug report. Since test program is very small, I am pasting it here: source files: si...@home_pc:~/test/header_file$ cat 1.c #include "1.h" int main() { F1 a; a.a = 1; return 0; } --------------------------------------------- si...@home_pc:~/test/header_file$ cat 1.h #ifndef F1_H typedef struct f1 F1; #include "2.h" struct f1 { int a; F2 a2; }; #define F1_H #endif --------------------------------------------- si...@home_pc:~/test/header_file$ cat 2.h #ifndef F2_H #define F2_H typedef struct f2 F2; #include "3.h" struct f2 { int a; F3 a3; }; #endif --------------------------------------------- si...@home_pc:~/test/header_file$ cat 3.h #ifndef F3_H #define F3_H typedef struct f3 F3; #include "1.h" struct f3 { int a; F1 a1; }; #endif --------------------------------------------- Finally 1.i: si...@home_pc:~/test/header_file$ cat 1.i # 1 "1.c" # 1 "<built-in>" # 1 "<command line>" # 1 "1.c" # 1 "1.h" 1 typedef struct f1 F1; # 1 "2.h" 1 typedef struct f2 F2; # 1 "3.h" 1 typedef struct f3 F3; # 1 "1.h" 1 typedef struct f1 F1; # 1 "2.h" 1 # 5 "1.h" 2 struct f1 { int a; F2 a2; }; # 6 "3.h" 2 struct f3 { int a; F1 a1; }; # 6 "2.h" 2 struct f2 { int a; F3 a3; }; # 5 "1.h" 2 struct f1 { int a; F2 a2; }; # 2 "1.c" 2 int main() { F1 a; a.a = 1; return 0; } -- Summary: gcc core dumping for unnecessary header file conflict Product: gcc Version: 4.1.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: nmdilipsimha at gmail dot com GCC build triplet: i486-linux-gnu GCC host triplet: i486-linux-gnu GCC target triplet: i486-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39433