cmFindBase: Track initial state with an enum

When logging a `WriteFindBaseEvent`, one of the triggers to log is the
change in the "found" status of a `find_` command. Track the difference
between "undefined", "found", and "tried before, but not found" so that
the transition can be detected reliably.

Co-Authored-by: Ryan Krattiger <ryan.krattiger@kitware.com>

Source/cmFindBase.cxx

@@ -79,8 +79,8 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
     return false;
   }
   this->VariableName = args[0];
-  if (this->CheckForVariableDefined()) {
-    this->AlreadyDefined = true;
+  this->InitialState = this->GetInitialState();
+  if (this->IsFound()) {
     return true;
   }
 
@@ -470,7 +470,7 @@ void cmFindBase::FillUserGuessPath()
   paths.AddSuffixes(this->SearchPathSuffixes);
 }
 
-bool cmFindBase::CheckForVariableDefined()
+cmFindBase::FindState cmFindBase::GetInitialState()
 {
   if (cmValue value = this->Makefile->GetDefinition(this->VariableName)) {
     cmState* state = this->Makefile->GetState();
@@ -496,10 +496,21 @@ bool cmFindBase::CheckForVariableDefined()
       if (cached && cacheType == cmStateEnums::UNINITIALIZED) {
         this->AlreadyInCacheWithoutMetaInfo = true;
       }
-      return true;
+      return FindState::Found;
     }
+    return FindState::NotFound;
   }
-  return false;
+  return FindState::Undefined;
+}
+
+bool cmFindBase::IsFound() const
+{
+  return this->InitialState == FindState::Found;
+}
+
+bool cmFindBase::IsDefined() const
+{
+  return this->InitialState != FindState::Undefined;
 }
 
 void cmFindBase::NormalizeFindResult()

Source/cmFindBase.h

@@ -40,10 +40,8 @@ protected:
   friend class cmFindBaseDebugState;
   void ExpandPaths();
 
-  // see if the VariableName is already set,
-  // also copy the documentation from the cache to VariableDocumentation
-  // if it has documentation in the cache
-  bool CheckForVariableDefined();
+  bool IsFound() const;
+  bool IsDefined() const;
 
   void NormalizeFindResult();
   void StoreFindResult(std::string const& value);
@@ -62,7 +60,6 @@ protected:
   // CMAKE_*_PATH CMAKE_SYSTEM_*_PATH FRAMEWORK|LIBRARY|INCLUDE|PROGRAM
   std::string EnvironmentPath; // LIB,INCLUDE
 
-  bool AlreadyDefined = false;
   bool AlreadyInCacheWithoutMetaInfo = false;
   bool StoreResultInCache = true;
 
@@ -71,6 +68,18 @@ protected:
   std::string ValidatorName;
 
 private:
+  enum class FindState
+  {
+    Undefined,
+    Found,
+    NotFound,
+  };
+  // see if the VariableName is already set,
+  // also copy the documentation from the cache to VariableDocumentation
+  // if it has documentation in the cache
+  FindState GetInitialState();
+  FindState InitialState = FindState::Undefined;
+
   // Add pieces of the search.
   void FillPackageRootPath();
   void FillCMakeVariablePath();

Source/cmFindLibraryCommand.cxx

@@ -44,7 +44,7 @@ bool cmFindLibraryCommand::InitialPass(std::vector<std::string> const& argsIn)
 
   this->DebugMode = this->ComputeIfDebugModeWanted(this->VariableName);
 
-  if (this->AlreadyDefined) {
+  if (this->IsFound()) {
     this->NormalizeFindResult();
     return true;
   }

Source/cmFindPathCommand.cxx

@@ -37,7 +37,7 @@ bool cmFindPathCommand::InitialPass(std::vector<std::string> const& argsIn)
 
   this->DebugMode = this->ComputeIfDebugModeWanted(this->VariableName);
 
-  if (this->AlreadyDefined) {
+  if (this->IsFound()) {
     this->NormalizeFindResult();
     return true;
   }

Source/cmFindProgramCommand.cxx

@@ -195,7 +195,7 @@ bool cmFindProgramCommand::InitialPass(std::vector<std::string> const& argsIn)
   }
   this->DebugMode = this->ComputeIfDebugModeWanted(this->VariableName);
 
-  if (this->AlreadyDefined) {
+  if (this->IsFound()) {
     this->NormalizeFindResult();
     return true;
   }