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).

1 files changed, 2 insertions, 42 deletions

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();
 }