[Bug d/102765] [11 Regression] GDC11 stopped inlining library functions and lambdas used by a binary search one-liner code

["siarhei.siamashka at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102765

--- Comment #4 from Siarhei Siamashka <siarhei.siamashka at gmail dot com> ---
First of all, it's my own fault for not just bisecting the GDC code from the
day one to figure out all the relevant details many months earlier. The code is
large and takes a lot of time to compile, so I was lazy. And I apologise for
this.

Now comments from https://forum.dlang.org/thread/sspkdp$1m4n$1@digitalmars.com
provided some missing bits of important information. I may be still wrong, so
please correct me if necessary, but the root cause of this performance
regression appears to be an attempt to fix the actual problem PR104317 in GDC11
via some excessively invasive PR99914 that ended up evolving GDC in a wrong
direction.

Just imagine someone encountering something like the examples from
https://stackoverflow.com/questions/3691835/why-uninitialized-global-variable-is-weak-symbol
and then suddenly making a strange conclusion that all template functions
should be non-inlineable in a C++ compiler (unless LTO is enabled). Looks like
that's exactly what happened to GDC. The D language standard documentation is
incomplete and this isn't helping. But the developers of the other D compilers
seem to have an opinion that inlining template functions is okay (due to the
same or at least similar ODR rules as in C++).