Enabling -fextended-identifiers by default

Joseph Myers joseph@codesourcery.com
Mon Nov 3 16:24:00 GMT 2014

I propose enabling -fextended-identifiers by default for the appropriate 
standard versions (i.e. all C++ versions, C99 and above for C - so enabled 
by default for C now the default C version is gnu11).  Any comments or 

The following is my list of desirable improvements in the existing 
-fextended-identifiers support or testcases for it, but I don't think 
these issues need to stop it from being enabled by default.

* C -aux-info.

* ObjC -gen-decls.

* Use DW_AT_use_UTF8 in DWARF-3 debug info for compilation units built
  with extended identifiers enabled (or unconditionally).

* cpplib spelling preservation; correct output for -d (UCNs), DWARF
  debug info for macros (UCNs), PCH and PCH tests.

* cpplib diagnostics (outputting characters or UCNs as appropriate
  depending on the locale, as done for identifiers in non-cpplib

* C++ test for UCN linking with C and extern "C".

* Testcase for pp-numbers containing UCNs, $ or other equivalent

* Debug info generation tests (at least add -g to existing tests, plus
  UCNs for fields / struct tags / enum values / goto labels / macros

* C++ translation of extended characters (including $@` and various
  control characters) to UCNs in phase 1 (note diagnostics thus
  needed, but not for C++11, for control characters in strings /
  character constants as those UCNs invalid).

* Actual UTF-8 in identifiers (?).

Joseph S. Myers

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