yihanaa added inline comments.
================ Comment at: clang/lib/Sema/SemaChecking.cpp:433 + + llvm::StringRef getFormatSpecifier(QualType T) { + if (auto *BT = T->getAs<BuiltinType>()) { ---------------- rsmith wrote: > rsmith wrote: > > aaron.ballman wrote: > > > yihanaa wrote: > > > > I think this is better maintained in "clang/AST/FormatString.h". For > > > > example analyze_printf::PrintfSpecifier can get format specifier, what > > > > do you all think about? > > > +1 to this suggestion -- my hope is that we could generalize it more then > > > as I notice there are missing specifiers for things like intmax_t, > > > size_t, ptrdiff_t, _Decimal types, etc. Plus, that will hopefully make it > > > easier for __builtin_dump_struct to benefit when new format specifiers > > > are added, such as ones for printing a _BitInt. > > I am somewhat uncertain: every one of these is making arbitrary choices > > about how to format the value, so it's not clear to me that this is general > > logic rather than something specific to `__builtin_dump_struct`. For > > example, using `%f` rather than one of the myriad other ways of formatting > > `double` is somewhat arbitrary. Using `%s` for any `const char*` is > > *extremely* arbitrary and will be wrong and will cause crashes in some > > cases, but it may be the pragmatically correct choice for a dumping > > utility. A general-purpose mechanism would use `%p` for all kinds of > > pointer. > > > > We could perhaps factor out the formatting for cases where there is a clear > > canonical default formatting, such as for integer types and probably `%p` > > for pointers, then call that from here with some special-casing, but > > without a second consumer for that functionality it's really not clear to > > me what form it should take. > I went ahead and did this, mostly to match concurrent changes to the old > implementation. There are a few cases where our existing "guess a format > specifier" logic does the wrong thing for dumping purposes, which I've > explicitly handled -- things like wanting to dump a `char` / `signed char` / > `unsigned char` member as a number rather than as a (potentially > non-printable or whitespace) character. When I was patching that old implementation, I found that for uint8_t, int8_t, Clang's existing "guess a format specifier" logic would treat the value as an integer, but for unsigned char, signed char, char types, it would Treat it as a character, please look at this example ( https://godbolt.org/z/ooqn4468T ), I guess this existing logic may have made some special judgment. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D124221/new/ https://reviews.llvm.org/D124221 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits