Threaded DRC access will write to this string, re-allocating the memory
without any synchronization between threads using the string. Comment
adding this listed performance as a reason for using shared strings.
Measured performance does not seem noticeably different in either case,
even with high-error count boards. If there is a case where the
performance is limiting, we can replace these wxStrings with
std::wstring and utilize fmt
Fixes https://gitlab.com/kicad/code/kicad/issues/9888
The basic problem is that the DRC engine does length testing and skew
testing by collecting all the diff pair constituent parts and pairing them
itself. Since each part is collected on its own, we need to ignore the
'B' unit when evaluating any conditional expressions. However, doing this
in general means that when evaluating "OwnClearance()" we also ignore the
'B' unit and return the diff pair CLEARANCE_CONSTRAINT when we shouldn't.
This implements a more discerning test which know what the current requested
constraint is when evaluating expressions.
See also https://forum.kicad.info/t/solved-custom-differencing-rule-not-working-drc/34034/6
Fixes https://gitlab.com/kicad/code/kicad/issues/11314
in most of files, including wx.h is not necessary, when only 2 or 3 wx files must be included.
Moreover, on windows, including wx.h sometimes create compil warnings about
shadowed vars defined in some specific windows headers.
Seth Hillbrand
Jeff Young
Erwan Rouault
Marek Roszko
jean-pierre charras
Mikolaj Wielgus
Tomasz Wlostowski