Emit macro expansion related diagnostics

In this third instalment the diagnostic machinery -- when faced with
the virtual location of a token resulting from macro expansion -- uses
the new linemap APIs to unwind the stack of macro expansions that led
to that token and emits a [hopefully] more useful message than what we
have today.

diagnostic_report_current_module has been slightly changed to use the
location given by client code instead of the global input_location
variable.  This results in more precise diagnostic locations in
general but then the patch adjusts some C++ tests which output changed
as a result of this.

Three new regression tests have been added.

The mandatory screenshot goes like this:

[dodji@adjoa gcc]$ cat -n test.c
     1    #define OPERATE(OPRD1, OPRT, OPRD2) \
     2      OPRD1 OPRT OPRD2;
     3
     4    #define SHIFTL(A,B) \
     5      OPERATE (A,<<,B)
     6
     7    #define MULT(A) \
     8      SHIFTL (A,1)
     9
    10    void
    11    g ()
    12    {
    13      MULT (1.0);/* 1.0 << 1; <-- so this is an error.  */
    14    }

[dodji@adjoa gcc]$ ./cc1 -quiet -ftrack-macro-expansion test.c
test.c: In function 'g':
test.c:5:14: erreur: invalid operands to binary << (have 'double' and 'int')
test.c:2:9: note: in expansion of macro 'OPERATE'
test.c:5:3: note: expanded from here
test.c:5:14: note: in expansion of macro 'SHIFTL'
test.c:8:3: note: expanded from here
test.c:8:3: note: in expansion of macro 'MULT2'
test.c:13:3: note: expanded from here

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@180083 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 3 insertions, 0 deletions

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 63e229ef7a8..c43869c3b31 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1171,6 +1171,9 @@ general_init (const char *argv0)
      can give warnings and errors.  */
   diagnostic_initialize (global_dc, N_OPTS);
   diagnostic_starter (global_dc) = default_tree_diagnostic_starter;
+  /* By default print macro expansion contexts in the diagnostic
+     finalizer -- for tokens resulting from macro macro expansion.  */
+  diagnostic_finalizer (global_dc) = virt_loc_aware_diagnostic_finalizer;
   /* Set a default printer.  Language specific initializations will
      override it later.  */
   pp_format_decoder (global_dc->printer) = &default_tree_printer;