On #3792 it was requested to put context-related diagnostic messages
prior to the diagnostic error. In order to support that, remove the
distinction that an error needs to come first on DiagnosticMessage.
We already needed to manually flush diagnostics along every path out of
the driver, so switch to a CHECK-failure if we get this wrong rather
than a potential use-after-lifetime bug.
Switch the driver to flush explicitly rather than using a bunch of
cleanup lambdas, now that we have checking that we get this right.
This is a follow-up after #3126.
The lack of comments makes it difficult to be sure, but if any of these
are necessary, I'd like to make sure there are comments to explain why a
specific value was shown (which I do add for diagnostics_ in this
change).
Followup for #2490
The switch of DiagnosticMessage to have DiagnosticMessage means we don't need to use unique_ptr. This means that copy constructors are implicit again and don't need to be avoided, but per discussion still keeping with moves. Comments on HandleDiagnostic try to capture the use of moves there.
I'm keeping DiagnosticLevel at the top-level, and adding some checking that notes are actually Notes.
Also, adding MakeMessage to unify some of the logic (this has particularly been bugging me around format_fn, and I ran into it here because of the Diagnostic -> DiagnosticMessage change). The addition of NoTypeDeduction is intended to avoid some duplicative comments that'd been piling up.
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
This is currently used once for PreviousDefinition in semantics.
This PR doesn't just add a builder, it also adds support to the emitter itself to collect notes attached to a diagnostic, and to the consumers and emitters to print all of them.
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Jon Ross-Perkins
Richard Smith
