There have been two bugs reported about the `else` and `elseif`
commands in the context of the tracing functionality and the json-v1
format (#23191#22315). In essence, the reported traces referred to
the layer of the stacktrace immediately on top of the expected ones.
This MR fixes both issues. My solution adds a new parameter to the
`PrintCommandTrace` function, `commandMissingFromStack`, that callers
can specify if the command they want to report a trace for is not a
regular part of the stack maintained in `cmMakefile`. This is only the
case for `else` and `elseif`. The other bug is fixed by having the
caller pass a `cmListFileBacktrace`, which helps in getting the right
lines, file names... for the reported command.
Fixes: #23191#22315
Tools using the json-v1 format might want to trace stack frames across
different `CMakeLists.txt` files, in order to, for example, provide
stacktraces that span from the top-level `CMakeLists.txt` in a
project. One would think that `frame` lets you do that, but it
doesn't, because it tells you the depth of the stack within the
current `CMakeLists.txt`, so it gets reset across calls to
`add_subdirectory`.
The solution involves adding a field with a "global frame". This value
gets incremented on calls to `add_subdirectory`, which makes it easier
for tools to reconstruct "global stacktraces".
I considered changing the current "frame" value, but I didn't because
it would be a breaking change. I cannot think of any use-case where
"frame" is more useful to "global-frame", but maybe I'm missing
something.
