Trace: add global_frame field to json-v1 format

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.

Help/manual/cmake.1.rst

@@ -298,7 +298,8 @@ Options
          "cmd": "add_executable",
          "args": ["foo", "bar"],
          "time": 1579512535.9687231,
-         "frame": 2
+         "frame": 2,
+         "global_frame": 4
        }
 
      The members are:
@@ -325,7 +326,13 @@ Options
        Timestamp (seconds since epoch) of the function call.
 
      ``frame``
-       Stack frame depth of the function that was called.
+       Stack frame depth of the function that was called, within the
+       context of the  ``CMakeLists.txt`` being processed currently.
+
+     ``global_frame``
+       Stack frame depth of the function that was called, tracked globally
+       across all ``CMakeLists.txt`` files involved in the trace. This field
+       was added in minor version 2 of the ``json-v1`` format.
 
      Additionally, the first JSON document outputted contains the
      ``version`` key for the current major and minor version of the
@@ -337,7 +344,7 @@ Options
        {
          "version": {
            "major": 1,
-           "minor": 1
+           "minor": 2
          }
        }
 

Help/release/dev/trace-global-frame.rst

@@ -0,0 +1,8 @@
+trace-global-frame
+------------------
+
+* Add the field ``global_frame`` to the json-v1 trace format. This
+  frame tracks the depth of the call stack globally across all
+  ``CMakeLists.txt`` files involved in the trace, and will let tools
+  reconstruct stack traces that span from the top-level ``CMakeLists.txt``
+  file of the project.

Source/cmMakefile.cxx

@@ -302,6 +302,8 @@ void cmMakefile::PrintCommandTrace(
       val["time"] = cmSystemTools::GetTime();
       val["frame"] =
         static_cast<Json::Value::UInt64>(this->ExecutionStatusStack.size());
+      val["global_frame"] =
+        static_cast<Json::Value::UInt64>(this->RecursionDepth);
       msg << Json::writeString(builder, val);
 #endif
       break;

Source/cmake.cxx

@@ -1434,7 +1434,7 @@ void cmake::PrintTraceFormatVersion()
       Json::StreamWriterBuilder builder;
       builder["indentation"] = "";
       version["major"] = 1;
-      version["minor"] = 1;
+      version["minor"] = 2;
       val["version"] = version;
       msg = Json::writeString(builder, val);
 #endif

Tests/RunCMake/CommandLine/trace-json-v1-check.py

@@ -46,8 +46,15 @@ required_traces = [
     {
         'args': msg_args,
         'cmd': 'message',
-        'frame': 3 if expand else 2
+        'frame': 3 if expand else 2,
+        'global_frame': 3 if expand else 2
     },
+    {
+        'args': ['STATUS', 'nested global_frame'],
+        'cmd': 'message',
+        'frame': 3,
+        'global_frame': 6 if expand else 5
+    }
 ]
 
 with open(trace_file, 'r') as fp:
@@ -56,15 +63,16 @@ with open(trace_file, 'r') as fp:
     assert sorted(vers.keys()) == ['version']
     assert sorted(vers['version'].keys()) == ['major', 'minor']
     assert vers['version']['major'] == 1
-    assert vers['version']['minor'] == 1
+    assert vers['version']['minor'] == 2
 
     for i in fp.readlines():
         line = json.loads(i)
-        assert sorted(line.keys()) == ['args', 'cmd', 'file', 'frame', 'line', 'time']
+        assert sorted(line.keys()) == ['args', 'cmd', 'file', 'frame', 'global_frame','line', 'time']
         assert isinstance(line['args'], list)
         assert isinstance(line['cmd'], unicode)
         assert isinstance(line['file'], unicode)
         assert isinstance(line['frame'], int)
+        assert isinstance(line['global_frame'], int)
         assert isinstance(line['line'], int)
         assert isinstance(line['time'], float)
 

Tests/RunCMake/CommandLine/trace-json-v1-nested/CMakeLists.txt

@@ -0,0 +1,9 @@
+function(f)
+    message(STATUS "nested global_frame")
+endfunction()
+
+function(g)
+    f()
+endfunction()
+
+g()

Tests/RunCMake/CommandLine/trace-json-v1.cmake

@@ -3,3 +3,4 @@ set(ASDF fff sss "  SPACES !!!  ")
 set(FOO 42)
 set(BAR " space in string!")
 message(STATUS fff ${ASDF} " ${FOO} ${BAR}" "  SPACES !!!  ")
+add_subdirectory(trace-json-v1-nested)

Tests/RunCMake/cmake_language/defer_call_trace_json-stderr.txt

@@ -1,5 +1,5 @@
-{"args":\["DEFER","CALL","message","Deferred Message"\],"cmd":"cmake_language","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":2,"line":2,"time":[0-9.]+}
+{"args":\["DEFER","CALL","message","Deferred Message"\],"cmd":"cmake_language","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":2,"global_frame":2,"line":2,"time":[0-9.]+}
-{"args":\["Immediate Message"\],"cmd":"message","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":2,"line":3,"time":[0-9.]+}
+{"args":\["Immediate Message"\],"cmd":"message","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":2,"global_frame":2,"line":3,"time":[0-9.]+}
 Immediate Message
-{"args":\["Deferred Message"],"cmd":"message","defer":"__0","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":1,"line":2,"time":[0-9.]+}
+{"args":\["Deferred Message"],"cmd":"message","defer":"__0","file":"[^"]*/Tests/RunCMake/cmake_language/defer_call_trace_json.cmake","frame":1,"global_frame":1,"line":2,"time":[0-9.]+}
 Deferred Message$