This commit adds `valueLocationReference` to function pointers and
function references. Thereby, users can navigate directly to the
pointed-to function from within the "variables" pane.
In general, it would be useful to also a add similar location references
also to member function pointers, `std::source_location`,
`std::function`, and many more. Doing so would require extending the
formatters to provide such a source code location.
There were two RFCs about this a while ago:
https://discourse.llvm.org/t/rfc-extending-formatters-with-a-source-code-reference/68375https://discourse.llvm.org/t/rfc-sbvalue-metadata-provider/68377/26
However, both RFCs ended without a conclusion. As such, this commit now
implements the lowest-hanging fruit, i.e. function pointers. If people
find it useful, I will revive the RFC afterwards.
This commit implements support for the "declaration location" recently
added by microsoft/debug-adapter-protocol#494 to the debug adapter
protocol.
For the `declarationLocationReference` we need a variable ID similar to
the `variablesReference`. I decided to simply reuse the
`variablesReference` here and renamed `Variables::expandable_variables`
and friends accordingly. Given that almost all variables have a
declaration location, we now assign those variable ids to all variables.
While `declarationLocationReference` effectively supersedes
`$__lldb_extensions.declaration`, I did not remove this extension, yet,
since I assume that there are some closed-source extensions which rely
on it.
I tested this against VS-Code Insiders. However, VS-Code Insiders
currently only supports `valueLoctionReference` and not
`declarationLocationReference`, yet. Locally, I hence published the
declaration locations as value locations, and VS Code Insiders navigated
to the expected places. Looking forward to proper VS Code support for
`declarationLocationReference`.
