Re: [PATCH Rust front-end v2 34/37] gccrs: add lang.opt

[Thomas Schwinge <thomas@codesourcery.com>]

Hi!

On 2022-09-14T15:39:47+0200, Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> On Wed, Aug 24, 2022 at 2:13 PM <herron.philip@googlemail.com> wrote:
>>
>> From: Philip Herron <philip.herron@embecosm.com>
>>
>> We have some rust specific langugage options note -fwrapv is enabled by
>> default in the code. We are trying to respect options such as
>> -Wunused-result which we get by porting over c++ no-discard for rust's
>> must-use attribute, so we have enabled these by default directly here.
>
> LGTM

Actually, NACK.  ;-)

See <https://gcc.gnu.org/PR105914>
"gccrs setting warn_unused_variable breaks thousands of non-Rust tests".
The 'Init(1)' in 'gcc/rust/lang.opt' are in conflict with any (default)
'Init(0)' in other '*.opt' files -- remember that all '*.opt' files are
processed together by GCC's "options machinery", and thus
'gcc/rust/lang.opt' may (and here, does) affect non-Rust front end code.

I do have a patch series adding a 'LangInit(@var{language}, @var{value})'
option property, and patches to use this in a lot of places (here and in
other front ends' '*.opt' files), where currently we implement such logic
in '*.cc' files; '[...]_init_options_struct' functions via
'LANG_HOOKS_INIT_OPTIONS_STRUCT' (those then largely become empty and may
be removed).  I assume this idea to be uncontroversial; I "just" need to
get it polished and submitted...


Grüße
 Thomas


>>  gcc/rust/lang.opt | 118 ++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 118 insertions(+)
>>  create mode 100644 gcc/rust/lang.opt
>>
>> diff --git a/gcc/rust/lang.opt b/gcc/rust/lang.opt
>> new file mode 100644
>> index 00000000000..1f6855ede1d
>> --- /dev/null
>> +++ b/gcc/rust/lang.opt
>> @@ -0,0 +1,118 @@
>> +; Options for the Rust front end.
>> +; Copyright (C) 2003-2022 Free Software Foundation, Inc.
>> +;
>> +; This file is part of GCC.
>> +;
>> +; GCC is free software; you can redistribute it and/or modify it under
>> +; the terms of the GNU General Public License as published by the Free
>> +; Software Foundation; either version 3, or (at your option) any later
>> +; version.
>> +;
>> +; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
>> +; WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> +; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
>> +; for more details.
>> +;
>> +; You should have received a copy of the GNU General Public License
>> +; along with GCC; see the file COPYING3.  If not see
>> +; <http://www.gnu.org/licenses/>.
>> +
>> +; See the GCC internals manual for a description of this file's format.
>> +
>> +; Please try to keep this file in ASCII collating order.
>> +
>> +; Describes command-line options used by this frontend
>> +
>> +Language
>> +Rust
>> +
>> +I
>> +Rust Joined Separate
>> +; Documented in c.opt
>> +
>> +L
>> +Rust Joined Separate
>> +; Not documented
>> +
>> +Wall
>> +Rust
>> +; Documented in c.opt
>> +
>> +Wunused-variable
>> +Rust Var(warn_unused_variable) Init(1) Warning
>> +; documented in common.opt
>> +
>> +Wunused-const-variable
>> +Rust Warning Alias(Wunused-const-variable=, 2, 0)
>> +Warn when a const variable is unused.
>> +
>> +Wunused-const-variable=
>> +Rust Joined RejectNegative UInteger Var(warn_unused_const_variable) Init(1) Warning LangEnabledBy(Rust,Wunused-variable, 1, 0) IntegerRange(0, 2)
>> +Warn when a const variable is unused.
>> +
>> +Wunused-result
>> +Rust Var(warn_unused_result) Init(1) Warning
>> +Warn if a caller of a function, marked with attribute warn_unused_result, does not use its return value.
>> +
>> +frust-crate=
>> +Rust Joined RejectNegative
>> +-frust-crate=<name>             Set the crate name for the compilation
>> +
>> +frust-debug
>> +Rust Var(flag_rust_debug)
>> +Dump various Rust front end internals.
>> +
>> +frust-dump-
>> +Rust Joined RejectNegative
>> +-frust-dump-<type>     Dump Rust frontend internal information.
>> +
>> +frust-max-recursion-depth=
>> +Rust RejectNegative Type(int) Var(rust_max_recursion_depth) Init(64)
>> +-frust-max-recursion-depth=integer
>> +
>> +frust-mangling=
>> +Rust Joined RejectNegative Enum(frust_mangling) Var(flag_rust_mangling)
>> +-frust-mangling=[legacy|v0]     Choose which version to use for name mangling
>> +
>> +Enum
>> +Name(frust_mangling) Type(int) UnknownError(unknown rust mangling option %qs)
>> +
>> +EnumValue
>> +Enum(frust_mangling) String(legacy) Value(0)
>> +
>> +EnumValue
>> +Enum(frust_mangling) String(v0) Value(1)
>> +
>> +frust-cfg=
>> +Rust Joined RejectNegative
>> +-frust-cfg=<name>             Set a config expansion option
>> +
>> +frust-edition=
>> +Rust Joined RejectNegative Enum(frust_edition) Var(flag_rust_edition)
>> +-frust-edition=[2015|2018|2021]             Choose which edition to use when compiling rust code
>> +
>> +Enum
>> +Name(frust_edition) Type(int) UnknownError(unknown rust edition %qs)
>> +
>> +EnumValue
>> +Enum(frust_edition) String(2015) Value(0)
>> +
>> +EnumValue
>> +Enum(frust_edition) String(2018) Value(1)
>> +
>> +EnumValue
>> +Enum(frust_edition) String(2021) Value(2)
>> +
>> +frust-embed-metadata
>> +Rust Var(flag_rust_embed_metadata)
>> +Flag to enable embeding metadata directly into object files
>> +
>> +frust-metadata-output=
>> +Rust Joined RejectNegative
>> +-frust-metadata-output=<path.rox>  Path to output crate metadata
>> +
>> +o
>> +Rust Joined Separate
>> +; Documented in common.opt
>> +
>> +; This comment is to ensure we retain the blank line above.
>> --
>> 2.25.1
>>
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