https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77462
Bug ID: 77462
Summary: Error message prints source from wrong file after
#line
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: d.frey at gmx dot de
Target Milestone: ---
When I use #line, I can make the compiler print a source line from another file
when it encounters an error. This is totally misleading.
Consider two files, first fool.cc:
#include "liar.hh"
int main()
{
static_assert( 2 + 2 == 4, "oops" );
}
and a second file liar.hh:
#line 5 "fool.cc"
static_assert( 2 + 2 == 5, "oops" );
If I now compile with GCC, I get:
frey@vbox::~/work/test/lie_to_me$ g++-6 -std=c++11 fool.cc
In file included from fool.cc:1:0:
fool.cc:5:3: error: static assertion failed: oops
static_assert( 2 + 2 == 4, "oops" );
^~~~~~~~~~~~~
Note the line says "2 + 2 == 4", which is the line from "fool.cc", not the one
where the error *actually* occurs, namely the one saying "2 + 2 == 5" from
"liar.hh". Clang gets it right:
frey@vbox:1:~/work/test/lie_to_me$ clang++-3.9 -std=c++11 fool.cc
In file included from fool.cc:1:
fool.cc:5:3: error: static_assert failed "oops"
static_assert( 2 + 2 == 5, "oops" );
^ ~~~~~~~~~~
1 error generated.
Yes, #line leads to "fool.cc:5:3", but that is fine and what is intended by
#line is AFAICT *not* to read the source line for the error message from that
file and line.
