find_*: Add debug logging infrastructure

Enable debug messages a new `--find-debug` command-line option or via
the `CMAKE_FIND_DEBUG_MODE` variable.

This work was started by Chris Wilson, continued by Ray Donnelly, and
then refactored by Robert Maynard to collect information into a single
message per find query.

Co-Author: Ray Donnelly <mingw.android@gmail.com>
Co-Author: Chris Wilson <chris+github@qwirx.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/Source/cmFindCommon.h b/Source/cmFindCommon.h
index 8177eac..916f3bc 100644
--- a/Source/cmFindCommon.h
+++ b/Source/cmFindCommon.h
@@ -30,8 +30,11 @@ public:
 
   void SetError(std::string const& e);
 
+  bool DebugModeEnabled() const { return this->DebugMode; }
+
 protected:
   friend class cmSearchPath;
+  friend class cmFindBaseDebugState;
 
   /** Used to define groups of path labels */
   class PathGroup : public cmPathLabel
@@ -96,6 +99,10 @@ protected:
   /** Compute the current default search modes based on global variables.  */
   void SelectDefaultSearchModes();
 
+  /** The `InitialPass` functions of the child classes should set
+      this->DebugMode to the result of this.  */
+  bool ComputeIfDebugModeWanted();
+
   // Path arguments prior to path manipulation routines
   std::vector<std::string> UserHintsArgs;
   std::vector<std::string> UserGuessArgs;
@@ -106,6 +113,8 @@ protected:
   bool CheckCommonArgument(std::string const& arg);
   void AddPathSuffix(std::string const& arg);
 
+  void DebugMessage(std::string const& msg) const;
+  bool DebugMode;
   bool NoDefaultPath;
   bool NoPackageRootPath;
   bool NoCMakePath;