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
After !6954 got merged, it has become easier for tools to get
full stack-traces for runtime traces of a CMake program. The trace
information already included in the JSON objects (line number, source
file path) allows tools that display these stack traces to print the
CMake source code associated to them. However, CMake commands may
spawn multiple lines, and the JSON information associated to a trace
only contains the line in which the command started, but not the one
in which it ended. If tools want to print stack traces along the
relevant source code, and they want to print the whole command
associated to the stack frame, they will have to implement their own
CMake language parser to know where the command ends.
In order to simplify the life of those who want to write tooling for
CMake, this commit adds a `line_end` field to the json-v1 trace
format. If a given command spans multiple lines, the `line_end` field
will contain the line of the last line spanned by the command (that of
the closing parenthesis associated to the command).
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.
Add the timestamp and stack depth of the function call to the JSON trace
output format. This information can be useful for cmake profiling and
call stack inspection (see e.g. https://github.com/volo-zyko/cmake-profile-stats).
Improve unit test to allow for varying set of keys to check in trace lines.
