Trace: process else and elseif commands correctly

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

3 files changed, 15 insertions, 1 deletions

diff --git a/Tests/RunCMake/CommandLine/trace-json-v1-check.py b/Tests/RunCMake/CommandLine/trace-json-v1-check.py
index 2ef1495..c4b95dc 100755
--- a/Tests/RunCMake/CommandLine/trace-json-v1-check.py
+++ b/Tests/RunCMake/CommandLine/trace-json-v1-check.py
@@ -56,6 +56,11 @@ required_traces = [
         'cmd': 'message',
         'frame': 3,
         'global_frame': 6 if expand else 5
+    },
+    {
+        'cmd': 'else',
+        'global_frame': 4 if expand else 3,
+        'line': 3
     }
 ]
 
@@ -98,4 +103,7 @@ with open(trace_file, 'r') as fp:
             if subset == j:
                 required_traces.remove(j)
 
-assert not required_traces
+assert not required_traces, (
+    "The following traces were expected to be part of the "
+    "output but weren't", required_traces
+)
diff --git a/Tests/RunCMake/CommandLine/trace-json-v1-nested/CMakeLists.txt b/Tests/RunCMake/CommandLine/trace-json-v1-nested/CMakeLists.txt
index 089a960..743f6de 100644
--- a/Tests/RunCMake/CommandLine/trace-json-v1-nested/CMakeLists.txt
+++ b/Tests/RunCMake/CommandLine/trace-json-v1-nested/CMakeLists.txt
@@ -1,3 +1,8 @@
+function(function_that_uses_else)
+    if(FALSE)
+    else()
+    endif()
+endfunction()
 function(f)
     message(STATUS "nested global_frame")
 endfunction()
diff --git a/Tests/RunCMake/CommandLine/trace-json-v1.cmake b/Tests/RunCMake/CommandLine/trace-json-v1.cmake
index 4ed6160..464eb1f 100644
--- a/Tests/RunCMake/CommandLine/trace-json-v1.cmake
+++ b/Tests/RunCMake/CommandLine/trace-json-v1.cmake
@@ -8,3 +8,4 @@ set(FOO 42)
 set(BAR " space in string!")
 message(STATUS fff ${ASDF} " ${FOO} ${BAR}" "  SPACES !!!  ")
 add_subdirectory(trace-json-v1-nested)
+function_that_uses_else()