How to compile gcc 6.4.0 with gcc 7.2 in Archlinux

Question

I am trying to compile gcc 6.4.0 independently with gcc 7.2 in Archlinux.

Configuration is as follows:

../configure --prefix=${INSTALL_PREFIX} --enable-languages=c,c++,fortran \
    --enable-threads=posix --enable-tls --enable-libgomp --enable-lto \
    --enable-shared --enable-static --disable-nls --disable-multilib \
    --with-fpmath=sse

While compiling, I got the following error in md-unwind-support.h:

md-unwind-support.h:65:47: error: dereferencing pointer to incomplete type 'struct ucontext'

I compared md-unwind-support.h between defined in gcc 6.4.0 and gcc 7.2.0 and found that struct ucontext is defined as ucontext_t in gcc 7.2.0.

So, I made some changes in md-unwind-support.h of gcc 6.4.0 source tree but got some kine of namespace issue as follows:

int std::uncaught_exceptions() should have been declared inside 'std'

I get stuck and have no idea about this issue.

Any help and advice will be helpful.

Answer 1

The follwing is a patch which summerizes what I did. In short, changes are made to struct ucontext to ucontext_t and struct sigaltstack pointer to void pointer, struct sigaltstack to stack_t.

diff -urN gcc-6.3.0/libgcc/config/i386/linux-unwind.h gcc-6.3.0.new/libgcc/config/i386/linux-unwind.h
--- gcc-6.3.0/libgcc/config/i386/linux-unwind.h 2016-01-04 23:30:50.000000000 +0900
+++ gcc-6.3.0.new/libgcc/config/i386/linux-unwind.h 2017-10-29 23:01:21.717240052 +0900
@@ -58,7 +58,7 @@
   if (*(unsigned char *)(pc+0) == 0x48
       && *(unsigned long long *)(pc+1) == RT_SIGRETURN_SYSCALL)
     {
-      struct ucontext *uc_ = context->cfa;
+      ucontext_t *uc_ = context->cfa;
       /* The void * cast is necessary to avoid an aliasing warning.
          The aliasing warning is correct, but should not be a problem
          because it does not alias anything.  */
@@ -138,7 +138,7 @@
  siginfo_t *pinfo;
  void *puc;
  siginfo_t info;
- struct ucontext uc;
+ ucontext_t uc;
       } *rt_ = context->cfa;
       /* The void * cast is necessary to avoid an aliasing warning.
          The aliasing warning is correct, but should not be a problem
diff -urN gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_linux.cc gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_linux.cc
--- gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_linux.cc 2015-11-23 18:07:18.000000000 +0900
+++ gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_linux.cc 2017-10-29 23:09:00.490577558 +0900
@@ -546,8 +546,7 @@
 }
 #endif

-uptr internal_sigaltstack(const struct sigaltstack *ss,
-                         struct sigaltstack *oss) {
+uptr internal_sigaltstack(const void *ss, void *oss) {
   return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
 }

diff -urN gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_linux.h gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_linux.h
--- gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_linux.h 2015-10-21 16:32:45.000000000 +0900
+++ gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_linux.h 2017-10-29 23:09:43.907244619 +0900
@@ -19,7 +19,6 @@
 #include "sanitizer_platform_limits_posix.h"

 struct link_map;  // Opaque type returned by dlopen().
-struct sigaltstack;

 namespace __sanitizer {
 // Dirent structure for getdents(). Note that this structure is different from
@@ -28,8 +27,7 @@

 // Syscall wrappers.
 uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
-uptr internal_sigaltstack(const struct sigaltstack* ss,
-                          struct sigaltstack* oss);
+uptr internal_sigaltstack(const void* ss, void* oss);
 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
     __sanitizer_sigset_t *oldset);
 void internal_sigfillset(__sanitizer_sigset_t *set);
diff -urN gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
--- gcc-6.3.0/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc 2015-10-21 16:32:45.000000000 +0900
+++ gcc-6.3.0.new/libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc 2017-10-29 23:08:07.260577074 +0900
@@ -267,7 +267,7 @@

   // Alternate stack for signal handling.
   InternalScopedBuffer<char> handler_stack_memory(kHandlerStackSize);
-  struct sigaltstack handler_stack;
+  stack_t handler_stack;
   internal_memset(&handler_stack, 0, sizeof(handler_stack));
   handler_stack.ss_sp = handler_stack_memory.data();
   handler_stack.ss_size = kHandlerStackSize;
diff -urN gcc-6.3.0/libsanitizer/tsan/tsan_platform_linux.cc gcc-6.3.0.new/libsanitizer/tsan/tsan_platform_linux.cc
--- gcc-6.3.0/libsanitizer/tsan/tsan_platform_linux.cc 2016-08-12 17:53:46.000000000 +0900
+++ gcc-6.3.0.new/libsanitizer/tsan/tsan_platform_linux.cc 2017-10-29 23:10:38.817245120 +0900
@@ -291,7 +291,7 @@
 int ExtractResolvFDs(void *state, int *fds, int nfd) {
 #if SANITIZER_LINUX
   int cnt = 0;
-  __res_state *statp = (__res_state*)state;
+  struct __res_state *statp = (struct __res_state*)state;
   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
     if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
       fds[cnt++] = statp->_u._ext.nssocks[i];

Answer 2

In order to have make to work you have to modify the file make_folder/libgcc/config/i386/linux_unwind.h where make_folder is the folder where you type the make command.

In linux_unwind.h you have to change struct ucontext *uc_ = context->cfa; on line 61 to struct ucontext_t *uc_ = context->cfa;

Thanks to Seong that told us what file to modify.

Answer 3

I finally resolved issue. I should have modified libgcc/config/i386/linux_unwind.h instead of directly md-unwind-support.h