cmake: Add an option to control what files needs to be traced

Even in relatively small projects using `--trace` (and `--trace-expand`)
may produce a lot of output.  When developing a custom module usually
one is interested in output of only a few particular modules.

Add a `--trace-source=<file>` option to enable tracing only a subset of
source files.  The final output would be only from requested modules,
ignoring anything else not matched to given filename(s).

1 files changed, 10 insertions, 0 deletions

diff --git a/Source/cmake.h b/Source/cmake.h
index c5d7cbb..9ac6935 100644
--- a/Source/cmake.h
+++ b/Source/cmake.h
@@ -307,6 +307,14 @@ public:
   void SetTrace(bool b) { this->Trace = b; }
   bool GetTraceExpand() { return this->TraceExpand; }
   void SetTraceExpand(bool b) { this->TraceExpand = b; }
+  void AddTraceSource(std::string const& file)
+  {
+    this->TraceOnlyThisSources.push_back(file);
+  }
+  std::vector<std::string> const& GetTraceSources() const
+  {
+    return this->TraceOnlyThisSources;
+  }
   bool GetWarnUninitialized() { return this->WarnUninitialized; }
   void SetWarnUninitialized(bool b) { this->WarnUninitialized = b; }
   bool GetWarnUnused() { return this->WarnUnused; }
@@ -481,6 +489,8 @@ private:
   cmState* State;
   cmState::Snapshot CurrentSnapshot;
 
+  std::vector<std::string> TraceOnlyThisSources;
+
   void UpdateConversionPathTable();
 
   // Print a list of valid generators to stderr.