[cfe-dev] libclang keep header files opened - [Windows]

Eran Ifrah eran.ifrah at gmail.com
Sat Jan 4 01:08:45 PST 2014

Hello list,

I am facing a problem with the recent version of libclang on Windows.

The first problem: file save permission error within codelite IDE:

In codelite IDE I am using libclang in the following manner:

1) When a file is loaded into the editor I am calling libclang API to
create a TU which is later then cache (up to 5 TUs are cached). Note that I
am using the preamble flag to boost completion speed (and indeed it does)
2) A subsequent calls to code complete (Ctrl-SPACE) are re-using the TU
(which works great and in acceptable response time)

The following causes an issue within codelite:

If I load into the IDE a file (e.g. file.cpp) which has an include
statement to another header file (e.g. file.h) - codelite will compile and
cache the TU for file.cpp
Now, if I will try to open, edit and save file.h - I will get a "Save"
error (this is because apparently the file.h is being kept opened by the

The only way to unlock and release the file is by calling
clang_disposeTranslationUnit() for the cache TU for file.cpp

I can workaround it in the IDE in 2 ways:
1) When a tab is changed inside the IDE - I can clear the TU cache. This
will probably work, but will force a recreation of the TU object each time
user loads the file
2) whenever user faces a write error (permission denied) codelite will
dispose the cached TU and try to save the file again (internally)

The Second problem:
My SSD drive size is about 120GB of free space, I noticed that its size was
reduced to ~70GB ... searching around the file system, I noticed that under
%TMP% there are hundreds of preamble*.pch files
It seems as if when disposing a TU the PCH file is not removed from the
file system.

Again, I worked around it by adding a cleaner thread that will periodically
remove all preamble*.pch files (and silently ignore those who are opened in

Eran Ifrah
Author of codelite, a cross platform open source C/C++ IDE:
wxCrafter, a wxWidgets RAD: http://wxcrafter.codelite.org
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