cmake: Remove broken '--warn-unused-vars' option

This option has been broken since commit b9f9915516 (cmMakefile: Remove
VarUsageStack., 2015-05-17, v3.3.0-rc1~52^2).  That commit removed the
check that an initialized variable has actually been used and caused the
option to warn on every variable ever set.  This was not caught by the
test suite because the test for the feature only checked that warnings
appear when needed and not that they do not appear when not needed.

The option was never very practical to use.  Remove it to avoid the
runtime cost of usage tracking and checks for every variable (which we
were doing even when the option was not used).

15 files changed, 7 insertions, 99 deletions

diff --git a/Source/QtDialog/CMakeSetupDialog.cxx b/Source/QtDialog/CMakeSetupDialog.cxx
index 6dbfe11..fcc8408 100644
--- a/Source/QtDialog/CMakeSetupDialog.cxx
+++ b/Source/QtDialog/CMakeSetupDialog.cxx
@@ -152,9 +152,6 @@ CMakeSetupDialog::CMakeSetupDialog()
   this->WarnUninitializedAction =
     OptionsMenu->addAction(tr("&Warn Uninitialized (--warn-uninitialized)"));
   this->WarnUninitializedAction->setCheckable(true);
-  this->WarnUnusedAction =
-    OptionsMenu->addAction(tr("&Warn Unused (--warn-unused-vars)"));
-  this->WarnUnusedAction->setCheckable(true);
 
   QAction* debugAction = OptionsMenu->addAction(tr("&Debug Output"));
   debugAction->setCheckable(true);
@@ -290,9 +287,6 @@ void CMakeSetupDialog::initialize()
   QObject::connect(this->WarnUninitializedAction, SIGNAL(triggered(bool)),
                    this->CMakeThread->cmakeInstance(),
                    SLOT(setWarnUninitializedMode(bool)));
-  QObject::connect(this->WarnUnusedAction, SIGNAL(triggered(bool)),
-                   this->CMakeThread->cmakeInstance(),
-                   SLOT(setWarnUnusedMode(bool)));
 
   if (!this->SourceDirectory->text().isEmpty() ||
       !this->BinaryDirectory->lineEdit()->text().isEmpty()) {
diff --git a/Source/QtDialog/CMakeSetupDialog.h b/Source/QtDialog/CMakeSetupDialog.h
index d1e2035..914be12 100644
--- a/Source/QtDialog/CMakeSetupDialog.h
+++ b/Source/QtDialog/CMakeSetupDialog.h
@@ -111,7 +111,6 @@ protected:
   QAction* ConfigureAction;
   QAction* GenerateAction;
   QAction* WarnUninitializedAction;
-  QAction* WarnUnusedAction;
   QAction* InstallForCommandLineAction;
   State CurrentState;
 
diff --git a/Source/QtDialog/QCMake.cxx b/Source/QtDialog/QCMake.cxx
index f0b967b..6090256 100644
--- a/Source/QtDialog/QCMake.cxx
+++ b/Source/QtDialog/QCMake.cxx
@@ -21,7 +21,6 @@ QCMake::QCMake(QObject* p)
   : QObject(p)
 {
   this->WarnUninitializedMode = false;
-  this->WarnUnusedMode = false;
   qRegisterMetaType<QCMakeProperty>();
   qRegisterMetaType<QCMakePropertyList>();
 
@@ -170,7 +169,6 @@ void QCMake::configure()
   this->CMakeInstance->SetGeneratorToolset(this->Toolset.toLocal8Bit().data());
   this->CMakeInstance->LoadCache();
   this->CMakeInstance->SetWarnUninitialized(this->WarnUninitializedMode);
-  this->CMakeInstance->SetWarnUnused(this->WarnUnusedMode);
   this->CMakeInstance->PreLoadCMakeFiles();
 
   InterruptFlag = 0;
@@ -478,11 +476,6 @@ void QCMake::setWarnUninitializedMode(bool value)
   this->WarnUninitializedMode = value;
 }
 
-void QCMake::setWarnUnusedMode(bool value)
-{
-  this->WarnUnusedMode = value;
-}
-
 void QCMake::checkOpenPossible()
 {
   std::string data = this->BinaryDirectory.toLocal8Bit().data();
diff --git a/Source/QtDialog/QCMake.h b/Source/QtDialog/QCMake.h
index 110a971..39555d6 100644
--- a/Source/QtDialog/QCMake.h
+++ b/Source/QtDialog/QCMake.h
@@ -114,8 +114,6 @@ public slots:
   void setDeprecatedWarningsAsErrors(bool value);
   /// set whether to run cmake with warnings about uninitialized variables
   void setWarnUninitializedMode(bool value);
-  /// set whether to run cmake with warnings about unused variables
-  void setWarnUnusedMode(bool value);
   /// check if project IDE open is possible and emit openPossible signal
   void checkOpenPossible();
 
@@ -175,8 +173,6 @@ protected:
   void stderrCallback(std::string const& msg);
 
   bool WarnUninitializedMode;
-  bool WarnUnusedMode;
-  bool WarnUnusedAllMode;
   QString SourceDirectory;
   QString BinaryDirectory;
   QString Generator;
diff --git a/Source/cmDefinitions.cxx b/Source/cmDefinitions.cxx
index 69a6427..4a4f87d 100644
--- a/Source/cmDefinitions.cxx
+++ b/Source/cmDefinitions.cxx
@@ -19,7 +19,6 @@ cmDefinitions::Def const& cmDefinitions::GetInternal(const std::string& key,
   {
     auto it = begin->Map.find(cm::String::borrow(key));
     if (it != begin->Map.end()) {
-      it->second.Used = true;
       return it->second;
     }
   }
@@ -108,16 +107,3 @@ void cmDefinitions::Unset(const std::string& key)
 {
   this->Map[key] = Def();
 }
-
-std::vector<std::string> cmDefinitions::UnusedKeys() const
-{
-  std::vector<std::string> keys;
-  keys.reserve(this->Map.size());
-  // Consider local definitions.
-  for (auto const& mi : this->Map) {
-    if (!mi.second.Used) {
-      keys.push_back(*mi.first.str_if_stable());
-    }
-  }
-  return keys;
-}
diff --git a/Source/cmDefinitions.h b/Source/cmDefinitions.h
index 0e38fb1..d57750a 100644
--- a/Source/cmDefinitions.h
+++ b/Source/cmDefinitions.h
@@ -48,9 +48,6 @@ public:
   /** Unset a definition.  */
   void Unset(const std::string& key);
 
-  /** List of unused keys.  */
-  std::vector<std::string> UnusedKeys() const;
-
 private:
   /** String with existence boolean.  */
   struct Def
@@ -62,7 +59,6 @@ private:
     {
     }
     cm::String Value;
-    bool Used = false;
   };
   static Def NoDef;
 
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index d34259f..25013df 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -83,7 +83,6 @@ cmMakefile::cmMakefile(cmGlobalGenerator* globalGenerator,
 {
   this->IsSourceFileTryCompile = false;
 
-  this->WarnUnused = this->GetCMakeInstance()->GetWarnUnused();
   this->CheckSystemVars = this->GetCMakeInstance()->GetCheckSystemVars();
 
   this->SuppressSideEffects = false;
@@ -751,7 +750,6 @@ void cmMakefile::ReadListFile(cmListFile const& listFile,
       break;
     }
   }
-  this->CheckForUnusedVariables();
 
   this->AddDefinition("CMAKE_PARENT_LIST_FILE", currentParentFile);
   this->AddDefinition("CMAKE_CURRENT_LIST_FILE", currentFile);
@@ -1511,8 +1509,6 @@ void cmMakefile::PopFunctionScope(bool reportError)
 #endif
 
   this->PopLoopBlockBarrier();
-
-  this->CheckForUnusedVariables();
 }
 
 void cmMakefile::PushMacroScope(std::string const& fileName,
@@ -1859,9 +1855,6 @@ void cmMakefile::AddSystemIncludeDirectories(const std::set<std::string>& incs)
 
 void cmMakefile::AddDefinition(const std::string& name, cm::string_view value)
 {
-  if (this->VariableInitialized(name)) {
-    this->LogUnused("changing definition", name);
-  }
   this->StateSnapshot.SetDefinition(name, value);
 
 #ifndef CMAKE_BOOTSTRAP
@@ -1922,16 +1915,6 @@ void cmMakefile::AddCacheDefinition(const std::string& name, const char* value,
   this->StateSnapshot.RemoveDefinition(name);
 }
 
-void cmMakefile::CheckForUnusedVariables() const
-{
-  if (!this->WarnUnused) {
-    return;
-  }
-  for (const std::string& key : this->StateSnapshot.UnusedKeys()) {
-    this->LogUnused("out of scope", key);
-  }
-}
-
 void cmMakefile::MarkVariableAsUsed(const std::string& var)
 {
   this->StateSnapshot.GetDefinition(var);
@@ -1959,29 +1942,8 @@ void cmMakefile::MaybeWarnUninitialized(std::string const& variable,
   }
 }
 
-void cmMakefile::LogUnused(const char* reason, const std::string& name) const
-{
-  if (this->WarnUnused) {
-    std::string path;
-    if (!this->ExecutionStatusStack.empty()) {
-      path = this->GetExecutionContext().FilePath;
-    } else {
-      path = cmStrCat(this->GetCurrentSourceDirectory(), "/CMakeLists.txt");
-    }
-
-    if (this->CheckSystemVars || this->IsProjectFile(path.c_str())) {
-      std::ostringstream msg;
-      msg << "unused variable (" << reason << ") \'" << name << "\'";
-      this->IssueMessage(MessageType::AUTHOR_WARNING, msg.str());
-    }
-  }
-}
-
 void cmMakefile::RemoveDefinition(const std::string& name)
 {
-  if (this->VariableInitialized(name)) {
-    this->LogUnused("unsetting", name);
-  }
   this->StateSnapshot.RemoveDefinition(name);
 #ifndef CMAKE_BOOTSTRAP
   cmVariableWatch* vv = this->GetVariableWatch();
@@ -3724,7 +3686,7 @@ int cmMakefile::TryCompile(const std::string& srcdir,
   if (cmakeArgs) {
     // FIXME: Workaround to ignore unused CLI variables in try-compile.
     //
-    // Ideally we should use SetArgs to honor options like --warn-unused-vars.
+    // Ideally we should use SetArgs for options like --no-warn-unused-cli.
     // However, there is a subtle problem when certain arguments are passed to
     // a macro wrapping around try_compile or try_run that does not escape
     // semicolons in its parameters but just passes ${ARGV} or ${ARGN}.  In
@@ -3743,7 +3705,7 @@ int cmMakefile::TryCompile(const std::string& srcdir,
     // the value VAR=a is sufficient for the try_compile or try_run to get the
     // correct result.  Calling SetArgs here would break such projects that
     // previously built.  Instead we work around the issue by never reporting
-    // unused arguments and ignoring options such as --warn-unused-vars.
+    // unused arguments and ignoring options such as --no-warn-unused-cli.
     cm.SetWarnUnusedCli(false);
     // cm.SetArgs(*cmakeArgs, true);
 
@@ -4247,8 +4209,6 @@ void cmMakefile::PopScope()
 
   this->PopLoopBlockBarrier();
 
-  this->CheckForUnusedVariables();
-
   this->PopSnapshot();
 }
 
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 332554e..045ded4 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -995,9 +995,6 @@ protected:
   // add link libraries and directories to the target
   void AddGlobalLinkInformation(cmTarget& target);
 
-  // Check for a an unused variable
-  void LogUnused(const char* reason, const std::string& name) const;
-
   mutable std::set<cmListFileContext> CMP0054ReportedIds;
 
   // libraries, classes, and executables
@@ -1233,10 +1230,6 @@ private:
                                  std::string const& config,
                                  const std::string& feature) const;
 
-  void CheckForUnusedVariables() const;
-
-  // Unused variable flags
-  bool WarnUnused;
   bool CheckSystemVars;
   bool CheckCMP0000;
   std::set<std::string> WarnedCMP0074;
diff --git a/Source/cmServerProtocol.cxx b/Source/cmServerProtocol.cxx
index 4f7131f..e586fd9 100644
--- a/Source/cmServerProtocol.cxx
+++ b/Source/cmServerProtocol.cxx
@@ -136,6 +136,7 @@ bool cmServerProtocol::Activate(cmServer* server,
   this->m_Server = server;
   this->m_CMakeInstance =
     cm::make_unique<cmake>(cmake::RoleProject, cmState::Project);
+  this->m_WarnUnused = false;
   const bool result = this->DoActivate(request, errorMessage);
   if (!result) {
     this->m_CMakeInstance = nullptr;
@@ -636,7 +637,7 @@ cmServerResponse cmServerProtocol1::ProcessGlobalSettings(
   obj[kTRACE_KEY] = cm->GetTrace();
   obj[kTRACE_EXPAND_KEY] = cm->GetTraceExpand();
   obj[kWARN_UNINITIALIZED_KEY] = cm->GetWarnUninitialized();
-  obj[kWARN_UNUSED_KEY] = cm->GetWarnUnused();
+  obj[kWARN_UNUSED_KEY] = m_WarnUnused;
   obj[kWARN_UNUSED_CLI_KEY] = cm->GetWarnUnusedCli();
   obj[kCHECK_SYSTEM_VARS_KEY] = cm->GetCheckSystemVars();
 
@@ -682,7 +683,7 @@ cmServerResponse cmServerProtocol1::ProcessSetGlobalSettings(
   setBool(request, kTRACE_EXPAND_KEY, [cm](bool e) { cm->SetTraceExpand(e); });
   setBool(request, kWARN_UNINITIALIZED_KEY,
           [cm](bool e) { cm->SetWarnUninitialized(e); });
-  setBool(request, kWARN_UNUSED_KEY, [cm](bool e) { cm->SetWarnUnused(e); });
+  setBool(request, kWARN_UNUSED_KEY, [this](bool e) { m_WarnUnused = e; });
   setBool(request, kWARN_UNUSED_CLI_KEY,
           [cm](bool e) { cm->SetWarnUnusedCli(e); });
   setBool(request, kCHECK_SYSTEM_VARS_KEY,
diff --git a/Source/cmServerProtocol.h b/Source/cmServerProtocol.h
index c71b7bf..6009e23 100644
--- a/Source/cmServerProtocol.h
+++ b/Source/cmServerProtocol.h
@@ -94,6 +94,7 @@ protected:
   // Implement protocol specific activation tasks here. Called from Activate().
   virtual bool DoActivate(const cmServerRequest& request,
                           std::string* errorMessage);
+  bool m_WarnUnused = false; // storage for legacy option
 
 private:
   std::unique_ptr<cmake> m_CMakeInstance;
diff --git a/Source/cmStateSnapshot.cxx b/Source/cmStateSnapshot.cxx
index 15a98af..cfabc3f 100644
--- a/Source/cmStateSnapshot.cxx
+++ b/Source/cmStateSnapshot.cxx
@@ -232,11 +232,6 @@ void cmStateSnapshot::RemoveDefinition(std::string const& name)
   this->Position->Vars->Unset(name);
 }
 
-std::vector<std::string> cmStateSnapshot::UnusedKeys() const
-{
-  return this->Position->Vars->UnusedKeys();
-}
-
 std::vector<std::string> cmStateSnapshot::ClosureKeys() const
 {
   return cmDefinitions::ClosureKeys(this->Position->Vars,
diff --git a/Source/cmStateSnapshot.h b/Source/cmStateSnapshot.h
index 021fd53..c19f174 100644
--- a/Source/cmStateSnapshot.h
+++ b/Source/cmStateSnapshot.h
@@ -28,7 +28,6 @@ public:
   bool IsInitialized(std::string const& name) const;
   void SetDefinition(std::string const& name, cm::string_view value);
   void RemoveDefinition(std::string const& name);
-  std::vector<std::string> UnusedKeys() const;
   std::vector<std::string> ClosureKeys() const;
   bool RaiseScope(std::string const& var, const char* varDef);
 
diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 27ecb4d..638f10e 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -773,8 +773,7 @@ void cmake::SetArgs(const std::vector<std::string>& args)
       std::cout << "Warn about uninitialized values.\n";
       this->SetWarnUninitialized(true);
     } else if (cmHasLiteralPrefix(arg, "--warn-unused-vars")) {
-      std::cout << "Finding unused variables.\n";
-      this->SetWarnUnused(true);
+      // Option was removed.
     } else if (cmHasLiteralPrefix(arg, "--no-warn-unused-cli")) {
       std::cout << "Not searching for unused variables given on the "
                 << "command line.\n";
diff --git a/Source/cmake.h b/Source/cmake.h
index c5d608f..0c4f429 100644
--- a/Source/cmake.h
+++ b/Source/cmake.h
@@ -450,8 +450,6 @@ public:
 
   bool GetWarnUninitialized() { return this->WarnUninitialized; }
   void SetWarnUninitialized(bool b) { this->WarnUninitialized = b; }
-  bool GetWarnUnused() { return this->WarnUnused; }
-  void SetWarnUnused(bool b) { this->WarnUnused = b; }
   bool GetWarnUnusedCli() { return this->WarnUnusedCli; }
   void SetWarnUnusedCli(bool b) { this->WarnUnusedCli = b; }
   bool GetCheckSystemVars() { return this->CheckSystemVars; }
@@ -605,7 +603,6 @@ private:
   TraceFormat TraceFormatVar = TRACE_HUMAN;
   cmGeneratedFileStream TraceFile;
   bool WarnUninitialized = false;
-  bool WarnUnused = false;
   bool WarnUnusedCli = true;
   bool CheckSystemVars = false;
   std::map<std::string, bool> UsedCliVariables;
diff --git a/Source/cmakemain.cxx b/Source/cmakemain.cxx
index 9fa6705..cebf34e 100644
--- a/Source/cmakemain.cxx
+++ b/Source/cmakemain.cxx
@@ -93,7 +93,6 @@ const char* cmDocumentationOptions[][2] = {
   { "--trace-redirect=<file>",
     "Redirect trace output to a file instead of stderr." },
   { "--warn-uninitialized", "Warn about uninitialized values." },
-  { "--warn-unused-vars", "Warn about unused variables." },
   { "--no-warn-unused-cli", "Don't warn about command line options." },
   { "--check-system-vars",
     "Find problems with variable usage in system "