[clangd] Surface errors from command-line parsing
Those errors are exposed at the first character of a file,
for a lack of a better place.
Previously, all errors were stored inside the AST and report
accordingly. However, errors in command-line argument parsing could
result in failure to produce the AST, so we need an alternative ways to
report those errors.
We take the following approach in this patch:
- buildCompilerInvocation() now requires an explicit DiagnosticConsumer.
- TUScheduler and TestTU now collect the diagnostics produced when parsing command line arguments. If pasing of the AST failed, diagnostics are reported via a new ParsingCallbacks::onFailedAST method. If parsing of the AST succeeded, any errors produced during command-line parsing are stored alongside the AST inside the ParsedAST instance and reported as previously by calling the ParsingCallbacks::onMainAST method;
- The client code that uses ClangdServer's DiagnosticConsumer does not need to change, it will receive new diagnostics in the onDiagnosticsReady() callback
Errors produced when parsing command-line arguments are collected using
the same StoreDiags class that is used to collect all other errors. They
are recognized by their location being invalid. IIUC, the location is
invalid as there is no source manager at this point, it is created at a
Although technically we might also get diagnostics that mention the
command-line arguments FileID with after the source manager was created
(and they have valid source locations), we choose to not handle those
and they are dropped as not coming from the main file. AFAICT, those
diagnostics should always be notes, therefore it's safe to drop them
without loosing too much information.
Reviewed By: kadircet
Subscribers: nridge, javed.absar, MaskRay, jkorous, arphaman, cfe-commits, gribozavr
Differential Revision: https://reviews.llvm.org/D66759