[Bug c++/107790] New: -fcontracts needs to add -lstdc++exp at the end of the collect2 options

[Bug c++/107790] New: -fcontracts needs to add -lstdc++exp at the end of the collect2 options

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107790

            Bug ID: 107790
           Summary: -fcontracts needs to add -lstdc++exp at the end of the
                    collect2 options
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: link-failure
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

This links OK:

g++20 fail.cc  -fcontracts

But this doesn't:

fail.cc: In function 'int f(int, int)':
fail.cc:1:45: warning: unused parameter '__r' [-Wunused-parameter]
    1 | int f(int x) [[pre: x > 0]] [[post r: r > 0]]
      |                                             ^

The problem is that static libs need to be listed after the .o file.

Test case:

int f(int x) [[pre: x > 0]] [[post r: r > 0]]
{
  return -5;
}

int main()
{
  f(42);
}

[Bug c++/107790] -fcontracts needs to add -lstdc++exp at the end of the collect2 options

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107790

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-11-21

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

Something like:
diff --git a/gcc/cp/g++spec.cc b/gcc/cp/g++spec.cc
index 257e49b7f3f..d4494bf266f 100644
--- a/gcc/cp/g++spec.cc
+++ b/gcc/cp/g++spec.cc
@@ -307,6 +307,7 @@ lang_specific_driver (struct cl_decoded_option
**in_decoded_options,

   /* Copy the 0th argument, i.e., the name of the program itself.  */
   new_decoded_options[j++] = decoded_options[i++];
+  bool needscxxexpadded = false;

   /* NOTE: We start at 1 now, not 0.  */
   while (i < argc)
@@ -357,8 +358,7 @@ lang_specific_driver (struct cl_decoded_option
**in_decoded_options,

       if ((args[i] & EXPERIMENTAL)
          && which_library == USE_LIBSTDCXX)
-       generate_option (OPT_l, "stdc++exp", 1, CL_DRIVER,
-                        &new_decoded_options[++j]);
+       needscxxexpadded = true;

       if ((args[i] & SKIPOPT) != 0)
        --j;
@@ -367,6 +367,10 @@ lang_specific_driver (struct cl_decoded_option
**in_decoded_options,
       j++;
     }

+  if (needscxxexpadded)
+    generate_option (OPT_l, "stdc++exp", 1, CL_DRIVER,
+                    &new_decoded_options[++j]);
+
   /* Add `-lstdc++' if we haven't already done so.  */
   if (library > 0)
     {

[Bug c++/107790] -fcontracts needs to add -lstdc++exp at the end of the collect2 options

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107790

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |13.0
         Resolution|---                         |FIXED

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed by r13-4223-gb20a3854c9f29 .

https://gcc.gnu.org/pipermail/gcc-cvs/2022-November/374653.html