[PATCH diagnostics/fortran] Handle two locations for the same diagnostic. Convert all gfc_warning_1 and gfc_notify_std_1 calls

[Manuel López-Ibáñez <lopezibanez at gmail dot com>]

The Fortran FE allows diagnostics with two different locations.
Depending on whether these locations are on the same line or not, this
may produce one or two caret lines. This is the last remaining issue
left to make Fortran diagnostics use the common code.

In the common diagnostics:

I added support for this in the common diagnostics, although Fortran
is the only user for now. The new common code should be flexible
enough to support the Clang style (which I guess is likely to be what
C/C++ FEs end up supporting sooner or later) while still supporting
the Fortran style.

Supporting this in the common diagnostics code requires having two
locations in struct diagnostic_info and two pointers in struct
text_info. That seems a waste and overtly complex. Thus, I moved the
new location array directly to struct text_info and added an accessor
function diagnostic_location().

In addition, this patch factors out the logic to determine whether two
locations should be shown in the same caret/locus line and the ability
to just print a caret line in diagnostic_print_caret_line(). These
functions are used by the common code and the Fortran FE.

In the Fortran FE:

These changes allow me to convert all Fortran FE diagnostic functions
to use the common code. For simplicity, this patch just converts
gfc_warning and gfc_notify_std. A follow-up Fortran-only patch will
convert gfc_error and remove a lot of unused code.

While checking that the new code was working correctly, I noticed that
the locations (as tracked by line-map) before and after the warning
given in badline.f were wrong. I fixed this and added two tests to
check that they are right from now on.

In addition, I added a new function gfc_warning_at to pass an explicit
location. I think this is better than having another %-code in
gfc_format_decoder. As you can see in that function, we are now doing
a lot of work just to print (1) and (2), when the location_t could
simply be passed explicitly to the diagnostic functions and replace
all %L and %C with explicit (1) and (2) in the calls. This will remove
completely gfc_format_decoder. But I'll leave that to Fortran devs if
they are interested in going that route.

I had to decide what to print for -fno-diagnostics-show-caret and
multiple locations. It has to be something that can be distinguished
from a duplicate diagnostic, such that the testsuite can parse it as
such. I chose to print:

file1:line1:col1: Error: (1)
file2:line2:col2: Error: message that mentions (1) and (2)

I could print something else if it pleases you, but the above should
only be seen if someone uses -fno-diagnostics-show-caret explicitly.

Bootstrapped and regression tested on x86_64-linux-gnu.

OK?


gcc/fortran/ChangeLog:

2015-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    PR fortran/44054

    Replace all calls to gfc_notify_std_1 with gfc_notify_std and
    gfc_warning_1 with gfc_warning.
    * decl.c (gfc_verify_c_interop_param): Here.
    * resolve.c (resolve_branch): Here.
    (resolve_fl_derived): Here.
    * dependency.c (gfc_check_argument_var_dependency):
    * scanner.c (preprocessor_line): Use gfc_warning_now_at. Fix line
    counter and locations before and after warning.
    * gfortran.h (gfc_warning_1, gfc_warning_now_1, gfc_notify_std_1):
    Delete.
    (gfc_warning_now_at): Declare.
    * error.c (gfc_warning_1): Delete.
    (gfc_notify_std_1): Delete.
    (gfc_warning_now_1): Delete.
    (gfc_format_decoder): Handle two locations.
    (gfc_diagnostic_build_prefix): Rename as
    gfc_diagnostic_build_kind_prefix.
    (gfc_diagnostic_build_locus_prefix): Take an expanded_location
    instead of diagnostic_info.
    (gfc_diagnostic_build_locus_prefix): Add overload that takes two
    expanded_location.
    (gfc_diagnostic_starter): Handle two locations.
    (gfc_warning_now_at): New.
    (gfc_diagnostics_init): Initialize caret_char array.
    (gfc_diagnostics_finish): Reset caret_char array to default.


gcc/cp/ChangeLog:

2015-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    * error.c (cp_diagnostic_starter): Use diagnostic_location
    function.
    (cp_print_error_function): Likewise.
    (cp_printer): Replace locus pointer with location array.

gcc/c/ChangeLog:

2015-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    * c-objc-common.c (c_tree_printer): Replace locus pointer with
    location array.

gcc/ChangeLog:

2015-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    * tree-pretty-print.c (percent_K_format): Replace locus pointer
    with location array.
    * tree-diagnostic.c (diagnostic_report_current_function): Use
    diagnostic_location function.
    (maybe_unwind_expanded_macro_loc): Likewise.
    (virt_loc_aware_diagnostic_finalizer): Likewise.
    (default_tree_printer): Replace locus pointer with location array.
    * diagnostic.c (diagnostic_initialize): Initialize caret_char array.
    (diagnostic_set_info_translated): Initialize second location.
    (diagnostic_show_locus): Handle two locations. Call
    diagnostic_print_caret_line.
    (diagnostic_print_caret_line): New.
    (default_diagnostic_starter): Use diagnostic_location function.
    (diagnostic_report_diagnostic): Use diagnostic_location function.
    (verbatim): Do not set text.locus.
    * diagnostic.h (struct diagnostic_info): Remove location field.
    (struct diagnostic_context): Make caret_char an array of two.
    (diagnostic_location): New inline.
    (diagnostic_expand_location): Handle two locations.
    (diagnostic_same_locus): New inline.
    (diagnostic_print_caret_line): Declare.
    * pretty-print.c (pp_printf): Do not set text.locus.
    (pp_verbatim): Do not set text.locus.
    * pretty-print.h (struct text_info): Replace locus pointer with
    location array.

gcc/testsuite/ChangeLog:

2015-04-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    PR fortran/44054
    * lib/gfortran-dg.exp: Update regex to handle two locations for
    the same diagnostic without caret.
    * gfortran.dg/badline.f: Test also that line numbers are correct
    before and after "left but not entered" warning.

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