C++ header files and crash issue

A continuing problem with kDevelop 5.3, 5.2 and 5.1.
Attempting to use kDevelop with the Audacity source code (
https://github.com/audacity/audacity) on Xubuntu 18.04 (and 16.04).

kDevelop fails to recognise class definitions in .h files. It can obviously
see them because it "Hints" that they are declared in the .h files, but it
still underlines them and suggests that they should be "std::<class name>".

I have found multiple accounts of this problem (example:
https://stackoverflow.com/questions/42699769/kdevelop-does-not-see-c-header-files)
but no solution that works. I have posted additional details on the
kDevelop forum: https://forum.kde.org/viewtopic.php?f=218&t=161463

An additional (and more serious) problem is that since this commit:
https://github.com/audacity/audacity/commit/87ef97abe24463abb87e5734
kDevelop crashes as parsing gets to (or close to) 100%.

Steve