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Re: [Tinycc-devel] -Werror=X (but ugly)
Re: [Tinycc-devel] -Werror=X (but ugly)
Wed, 28 Jul 2021 16:51:06 +0200
grischka wrote in
|Steffen Nurpmeso wrote:
|>| gcc -Wwrite-strings -Werror=discarded-qualifiers
|> Hm. Well then this part is not compatible it seems.
|Not compatible and cannot work:
| const char *xxx = "123"; /* no warning or error here */
| foo(); /* nobody said we would want this to stop */
| $ tcc -Werror=write-strings ...
| test.c:8: error: implicit declaration of function 'foo'
|Because -Wwrite-strings is NOT a warning option, really.
| const char *xxx = "123";
|tcc would complain the "discarded const qualifier" but it cannot
|track variables and code flow at compile-time in order to know
|that some pointer came from a string, originally.
I.. have a hard time parsing that, there already is
-Wwrite-strings and -Werror=write-strings just propagates the
according bit to make it an error state? That is all i know.
For me the -Werror thing is done for now, sorry for the necessary
fixups, i am a bit chaotic, for public shared repos i should just
let things rest for a few days and when it is still ok, then push.
In order to be better than what is now in -- what is missing is
that "-Werror -Wno-error=write-strings" does not error out for any
write-strings error, i.e., that specific errors can be disabled --
i had to wrap my head around the control flow of the code
generator, because for write-strings (all others would work out),
it just sets a VT_CONSTANT bit or so, then the generator continues
over several levels, then some *_cast_* function actually emits
a tcc_warning() (i could not figure out when the *_cast_* function
that actually emits the write-strings is actually called, from
looking say ten minutes). I thought about "quick and dirties":
- Just call tcc_warning() directly: would result in two log
messages unless the first would error out.
I could rename NEED_WARNING() to WANT_WARNING() and add
a WANT_ERROR(), and call tcc_warning() only then, in order to
- Add some field and another VT_ bit to indicate that field is
set, in order to pick it up later.
Then there could be another tcc_warn_or_err() which takes the
actual "enum warn_option" as its first argument.
I actually had this implementation fully implemented
yesterday, with error1() still backing all of the warn
functions, but for the write-strings case in the generator.
- Add a bit like WARN_IGNORE_ERR_NEXT, set this from within
NEED_WARNING() when a specific error is disabled but the
warning as such shall occur. Then clear that bit again in
tcc_warning() (aka error1()).
I was thinking of this, and it also would work everywhere, but
i did not know whether it will work out for the code generator
and the write-strings thing. Because _if_ another error
occurs in the generator _before_ we actually call
tcc_warning(), then of course a hard error could be falsely
|> I have never
|> tested it that much, i usually step in when somewhere the build
|> fails or spits warnings like grazy. Actually i have given up on
|> managing the mess that happens from compiler development.
|Yes, the mess ... eventually it can be reduced:
|$ git log -1 --shortstat --oneline eadcee65
|eadcee65 macos: yet another tbd adjustment
|8 files changed, 155 insertions(+), 169 deletions(-)
|14 lines less, same functionality (although Christian claims that
|it's broken since, who knows... ;)
|> Unfortunately tcc_warning() does not take arguments itself ...
|I would (maybe) go for
| tcc_warning(On_warn_badthing "bad thing did happen with %s", stuff);
| #define On_warn_badthing "\005"
|While not sooo nice without a comma, it would allow to "manage away"
|quite a few existing 'if (s1->warn_...)' clauses already and seems
|somewhat easily extensible.
Linux syslog thing is also an idea, but not for code generator :)
|With some luck one might be able to implement the feature (-Werror= etc.)
|and come out with +/- zero or even less additional lines required.
|Currently it still adds 78 lines total though:
|$ git diff --shortstat a7a138~1 2709b7
|8 files changed, 126 insertions(+), 48 deletions(-)
The enum adds quite a bit on top of it; the addition of
set_W_flag() is, hmm, not nice, but i hope the current approach is
not too heavy.
Keep on going tcc :)
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)