1 files changed, 51 insertions, 27 deletions

diff --git a/Source/cmVariableWatchCommand.cxx b/Source/cmVariableWatchCommand.cxx
index 5fe55bd53..f2c8f3cdb 100644
--- a/Source/cmVariableWatchCommand.cxx
+++ b/Source/cmVariableWatchCommand.cxx
@@ -2,12 +2,14 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmVariableWatchCommand.h"
 
-#include <sstream>
+#include <memory>
+#include <utility>
 
 #include "cmExecutionStatus.h"
 #include "cmListFileCache.h"
 #include "cmMakefile.h"
 #include "cmMessageType.h"
+#include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmVariableWatch.h"
 #include "cmake.h"
@@ -54,24 +56,22 @@ static void cmVariableWatchCommandVariableAccessed(const std::string& variable,
     newLFF.Arguments.emplace_back(stack, cmListFileArgument::Quoted, 9999);
     newLFF.Name = data->Command;
     newLFF.Line = 9999;
-    cmExecutionStatus status;
+    cmExecutionStatus status(*makefile);
     if (!makefile->ExecuteCommand(newLFF, status)) {
-      std::ostringstream error;
-      error << "Error in cmake code at\nUnknown:0:\n"
-            << "A command failed during the invocation of callback \""
-            << data->Command << "\".";
-      cmSystemTools::Error(error.str());
+      cmSystemTools::Error(
+        cmStrCat("Error in cmake code at\nUnknown:0:\nA command failed "
+                 "during the invocation of callback \"",
+                 data->Command, "\"."));
       data->InCallback = false;
       return;
     }
     processed = true;
   }
   if (!processed) {
-    std::ostringstream msg;
-    msg << "Variable \"" << variable << "\" was accessed using "
-        << accessString << " with value \"" << (newValue ? newValue : "")
-        << "\".";
-    makefile->IssueMessage(MessageType::LOG, msg.str());
+    makefile->IssueMessage(
+      MessageType::LOG,
+      cmStrCat("Variable \"", variable, "\" was accessed using ", accessString,
+               " with value \"", (newValue ? newValue : ""), "\"."));
   }
 
   data->InCallback = false;
@@ -84,21 +84,46 @@ static void deleteVariableWatchCallbackData(void* client_data)
   delete data;
 }
 
-cmVariableWatchCommand::cmVariableWatchCommand() = default;
-
-cmVariableWatchCommand::~cmVariableWatchCommand()
+/** This command does not really have a final pass but it needs to
+    stay alive since it owns variable watch callback information. */
+class FinalAction
 {
-  for (std::string const& wv : this->WatchedVariables) {
-    this->Makefile->GetCMakeInstance()->GetVariableWatch()->RemoveWatch(
-      wv, cmVariableWatchCommandVariableAccessed);
+public:
+  /* NOLINTNEXTLINE(performance-unnecessary-value-param) */
+  FinalAction(cmMakefile* makefile, std::string variable)
+    : Action(std::make_shared<Impl>(makefile, std::move(variable)))
+  {
   }
-}
 
-bool cmVariableWatchCommand::InitialPass(std::vector<std::string> const& args,
-                                         cmExecutionStatus&)
+  void operator()(cmMakefile&) const {}
+
+private:
+  struct Impl
+  {
+    Impl(cmMakefile* makefile, std::string variable)
+      : Makefile(makefile)
+      , Variable(std::move(variable))
+    {
+    }
+
+    ~Impl()
+    {
+      this->Makefile->GetCMakeInstance()->GetVariableWatch()->RemoveWatch(
+        this->Variable, cmVariableWatchCommandVariableAccessed);
+    }
+
+    cmMakefile* Makefile;
+    std::string Variable;
+  };
+
+  std::shared_ptr<Impl const> Action;
+};
+
+bool cmVariableWatchCommand(std::vector<std::string> const& args,
+                            cmExecutionStatus& status)
 {
   if (args.empty()) {
-    this->SetError("must be called with at least one argument.");
+    status.SetError("must be called with at least one argument.");
     return false;
   }
   std::string const& variable = args[0];
@@ -107,9 +132,7 @@ bool cmVariableWatchCommand::InitialPass(std::vector<std::string> const& args,
     command = args[1];
   }
   if (variable == "CMAKE_CURRENT_LIST_FILE") {
-    std::ostringstream ostr;
-    ostr << "cannot be set on the variable: " << variable;
-    this->SetError(ostr.str());
+    status.SetError(cmStrCat("cannot be set on the variable: ", variable));
     return false;
   }
 
@@ -118,13 +141,14 @@ bool cmVariableWatchCommand::InitialPass(std::vector<std::string> const& args,
   data->InCallback = false;
   data->Command = command;
 
-  this->WatchedVariables.insert(variable);
-  if (!this->Makefile->GetCMakeInstance()->GetVariableWatch()->AddWatch(
+  if (!status.GetMakefile().GetCMakeInstance()->GetVariableWatch()->AddWatch(
         variable, cmVariableWatchCommandVariableAccessed, data,
         deleteVariableWatchCallbackData)) {
     deleteVariableWatchCallbackData(data);
     return false;
   }
 
+  status.GetMakefile().AddFinalAction(
+    FinalAction(&status.GetMakefile(), variable));
   return true;
 }