Rather than replacing the code completion file
on the `CompilerInstance` whenever we do a cached
top-level completion, let's set a new main module
instead.
This allows us to properly update the
`LoadedModules` map, and allows the retrieval of
the code completion file to be turned into a
request.
Check if dependencies are modified since the last checking.
Dependencies:
- Other source files in the current module
- Dependent files collected by the dependency tracker
When:
- If the last dependency check was over N (defaults to 5) seconds ago
Invalidate if:
- The dependency file is missing
- The modification time of the dependecy is greater than the last check
- If the modification time is zero, compare the content using the file
system from the previous completion and the current completion
rdar://problem/62336432
if fast-completion is enabled. So they have higher chance to use the cached
completion instance.
If it's disabled, don't block, use an ephemeral instance so we can peform
multiple completions simultaneously.
To controls the lifetime of CompilerInstance within CompletionIntance.
- Prevent from using the same CompilerInstance from multiple completion
requests
- Separate the stacktrace between "fast" and "normal" completions
- Further code consolidation between various completion-like requests
- Introduce ide::CompletionInstance to manage CompilerInstance
- `CompletionInstance` vends the cached CompilerInstance when:
-- The compiler arguments (i.e. CompilerInvocation) has has not changed
-- The primary file is the same
-- The completion happens inside function bodies in both previous and
current completion
-- The interface hash of the primary file has not changed
- Otherwise, it vends a fresh CompilerInstance and cache it for the next
completion
rdar://problem/20787086
