TestUseSourceCache attempts to write to a build artifact copied from the
source tree, and asserts the write succeeded. If the source tree is read
only, the copy will also be read only, causing it to fail. When
producing the build artifact, ensure that it is writable.
Summary:
...and replace it with m_last_file_spec instead.
When Source Cache is enabled, the value stored in m_last_file_sp is
already in the Source Cache, and caching it again in SourceManager
brings no extra benefit. All we need is to "remember" the last used
file, and FileSpec can serve the same purpose.
When Source Cache is disabled, the user explicitly requested no caching
of source files, and therefore, m_last_file_sp should NOT be used.
Bug: llvm.org/PR45310
Depends on D76805.
Reviewers: labath, jingham
Reviewed By: jingham
Subscribers: labath, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D76806
