gnu gcc search path

[Sam Darwin]

Hi,

Regarding https://cygwin.com/packages/summary/gcc-g++.html  This is a
(perhaps) esoteric question about how gnu gcc should operate.  It says at
https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html  "By default, the
preprocessor looks for header files included by the quote form of the
directive #include "file" first relative to the directory of the current
file," When building boost C++ libraries on an earlier version of cygwin
this used to work fine.  Now, updating to a newer cygwin version on
Appveyor, "APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019"  , it has
broken..

Errors appear such as

"fatal error: zutil.h: No such file or directory 8 | #include "zutil.h"
compilation terminated."

"No such file or directory."

What do you think? It can't find the header file, which happens to be in
the same directory, the current directory.    It seems like a bug, however,
if it's intended behavior, and the current directory has been removed from
the search path, then could a command-line flag be provided to optionally
re-enable the previous functionality?