https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87364
--- Comment #5 from Will Wray <wjwray at gmail dot com> --- re: https://gcc.gnu.org/ml/gcc/2018-02/msg00009.html discussion on removing literal suffixes from Integral constants (part a bigger conversation I'll pick up on below). That change brought GCC into line with clang and MSVC which both currently output plain digits with no distinguishing type info. Unfortunately, plain digits output fails to distinguish non-type template Args with same values but different Integral types. To see how this discussion relates to enumeration constants we must distinguish non-enumerated from enumerated values. For non-enumerated values clang and MSVC output plain digits while GCC outputs a C-style cast* (unchanged by this patch). For enumerated values the patch here brings GCC into line with current clang and MSVC - all three now output enumerator ids* (current MSVC outputs duplicate-value ids as-if non-enumerated). (*ids and cast type are output with nested-specifier sequence.) Clang & MSVC discussion ----------------------- I started a thread with Clang devs about adding type info to enums: __PRETTY_FUNCTION__ output loses enum type info for non-enumerated values http://lists.llvm.org/pipermail/cfe-dev/2018-September/059229.html (I also submitted a broader request to MSVC https://developercommunity.visualstudio.com/content/problem/339663/improve-pretty-print-of-integral-non-type-template.html) Richard Smith is open to the idea of Clang adding type info where needed. He points out that the type info is only needed for deduced arguments, which I interpret to mean 'auto' in C++17 but can be concept in C++20. He singles out enum printing as a case where it may be OK to always print the type, arguing that implicit conversion from integer is not allowed. Mr Smith expanded the thread to cover - General non-type template arguments: Integral constants and more ----------------------------------- Picking up here on the bigger conversation, which really belongs elsewhere. In the linked thread https://gcc.gnu.org/ml/gcc/2018-02/msg00030.html Martin Sebor: For auto, since it's new, a viable alternative might be to standardize the debug info format so that eventually all producers will converge on it. But even that approach won't help users of existing compilers. C++20 generalises template non-type arguments to include LiteralType https://en.cppreference.com/w/cpp/language/template_parameters I doubt anyone considered yet what this means for debug info. How do you pretty-print a general non-scalar non-type Arg constant? Implementations will have to deal with this somehow (or ignore it). Without consensus we'll get greater divergence. This provides motivation NOW to discuss a general standard format. While this is outside the remit of the C++ standards process requirements for debug info / pretty-print should feed back to it. For instance, it'd be useful for non-type Args to have a unique, canonical constructor, akin to aggregate initialization perhaps. Where best to pick up this discussion towards standard debug info?
