We store custom command rule hashes in CMakeFiles/CMakeRuleHashes.txt
persistently across CMake runs. When the rule hash changes we delete
the custom command output file and write a new hash into the persistence
file.
This functionality was first added by the commit 'Introduce "rule
hashes" to help rebuild files when rules change.' (2008-06-02).
However, the implementation in cmGlobalGenerator::CheckRuleHashes kept
the file open for read when attempting to rewrite a new file. On
Windows filesystems this prevented the new version of the file from
being written! This caused the first set of rule hashes to be used
forever within a build tree, meaning that all custom commands whose
rules changed would be rebuilt every time CMake regenerated the build
tree.
In this commit we address the problem by splitting the read and write
operations into separate methods. This ensures that the input stream is
closed before the output stream opens the file.
We use 'git diff-index' to detect local modifications after pull. On
some filesystems the work tree timestamps of a few files may be dated
after the index, making them appear as locally modified. We address the
problem by using 'git update-index --refresh' to refresh the index and
avoid false local modifications.
Our internal path processing methods assume no trailing slashes, but bzr
adds trailing slashes to updated directories. This can lead to empty
entries in Update.xml files. We address the problem by stripping the
slashes as soon as they are parsed.
Cygwin versions .dll files by putting the version number in the file
name. Our fix to issue #3571 taught CMake to do this, but it used the
VERSION target property. It is better to use the SOVERSION property
since that is the interface (rather than implementation) version.
Change based on patch from issue #10122.
When building on Cygwin without -mwin32, the _WIN32 macro may not be
defined. SharedForward must still set the PATH environment variable to
ensure runtime dependencies are found.
The 'ldd' wrapping feature uses 'cygcheck' for now since a real ldd tool
is not available in Cygwin 1.5. We can change to use the real ldd when
we choose to stop supporting legacy Cygwin and require 1.7.
Brad King
KWSys Robot
David Cole
Zach Mullen
Bill Hoffman
Dave Partyka
Alexander Neundorf