On 7/22/19 5:26 PM, Jeff Law wrote:
On 7/22/19 3:54 PM, Martin Sebor wrote:
While resolving PR80545 - option -Wstringop-overflow not recognized
by Fortran, I discovered that a command line options that's supported
only by a subset of languages is considered as enabled when tested
by the middle-end even when the current language doesn't support
the option.
When the option controls a warning, there is no good way to suppress
its false positives via the usual mechanisms (i.e., specifying
-Wno-stringop-overflow either on the command line or via a pragma)
because the option is not recognized by the languages that do not
support it.
The attached patch arranges for such options to be treated as disabled
when queried by the middle-end when the current language doesn't support
them. The fix wasn't as straightforward as testing
lang_hooks.option_lang_mask () in the diagnostics subsystem because
it doesn't have access to lang_hooks. To get around it the patch adds
a new member, diagnostic_context::lang_mask, and initializes it with
the result of the hook.
To make debugging and testing this fix easier I enhanced the output
of the -Q --help= options to clearly indicate when an otherwise
recognized option isn't supported by a front-end. For example,
where the current trunk prints
-Walign-commons [enabled]
for the Fortran-only option -Walign-commons even when GCC is invoked
via a driver for a language like C or C++, with the patch applied it
prints
-Walign-commons [available in Fortran]
I also changed the output to indicate the what option an alias
is for, so that for example the -Wattribute-alias option that's
an alias for -Wattribute-alias=1 is shown with the alias target
as the value:
-Wattribute-alias -Wattribute-alias=1
Besides this, I also corrected the printing of byte-size arguments
(they were sliced from 64 to 32 bits).
Martin
gcc-80545.diff
PR driver/80545 - option -Wstringop-overflow not recognized by Fortran
gcc/cp/ChangeLog:
PR driver/80545
* decl.c (finish_function): Use lang_mask.
gcc/testsuite/ChangeLog:
PR driver/80545
* gcc.misc-tests/help.exp: Add tests.
* lib/options.exp: Handle C++.
gcc/ChangeLog:
PR driver/80545
* diagnostic.c (diagnostic_classify_diagnostic): Use lang_mask.
(diagnostic_report_diagnostic): Same.
* diagnostic.h (diagnostic_context::option_enabled): Add an argument.
(diagnostic_context::lang_mask): New data member.
* ipa-pure-const.c (suggest_attribute): Use
lang_hooks.option_lang_mask ().
* opts-common.c (option_enabled): Handle new argument.
(get_option_state): Pass an additional argument.
* opts.c (print_filtered_help): Print supported languages for
unsupported options. Adjust printing of current state.
* opts.h (option_enabled): Add argument.
* toplev.c (print_switch_values): Use lang_mask.
(general_init): Set global_dc->lang_mask.
Ironically this might have helped me today. I was looking at a case
where an LTO build get a fatal warning, but the non-LTO build got a
different (and non-fatal due to flags warning). It wasn't until I
started debugging the diagnostic machinery that I realized -Wall was a
language specific flag and that accounted for the difference between the
LTO and non-LTO builds.
I think this is OK, but give other folks 48hrs to chime in just in case.
Having heard no concerns I just checked it in as r273771.
Martin
