We're (currently) not aware of any actual use of 'ht_identifier's with NUL
characters embedded; its 'len' field appears to exist for optimization
purposes, since "forever". Before 'struct ht_identifier' was added in
commit 2a967f3d3a (Subversion r42334), we had in
'gcc/cpplib.h:struct cpp_hashnode': 'unsigned short len', or earlier 'length',
earlier in 'gcc/cpphash.h:struct hashnode': 'unsigned short length', earlier
'size_t length' with comment: "length of token, for quick comparison", earlier
'int length', ever since the 'gcc/cpp*' files were added in
commit 7f2935c734 (Subversion r9191).
This amends commit f3b957ea8b
"pch: Fix streaming of strings with embedded null bytes".
gcc/
* doc/gty.texi (GTY Options) <string_length>: Enhance.
libcpp/
* include/symtab.h (struct ht_identifier): Document different
rationale.