variable_watch: trigger on variables set via PARENT_SCOPE

Make sure that we also trigger variable watches when a variable
is set in the parent scope.

Fixes: #17827

Source/cmMakefile.cxx

@@ -3838,7 +3838,16 @@ void cmMakefile::RaiseScope(const std::string& var, const char* varDef)
     std::ostringstream m;
     m << "Cannot set \"" << var << "\": current scope has no parent.";
     this->IssueMessage(cmake::AUTHOR_WARNING, m.str());
+    return;
   }
+
+#ifdef CMAKE_BUILD_WITH_CMAKE
+  cmVariableWatch* vv = this->GetVariableWatch();
+  if (vv) {
+    vv->VariableAccessed(var, cmVariableWatch::VARIABLE_MODIFIED_ACCESS,
+                         varDef, this);
+  }
+#endif
 }
 
 cmTarget* cmMakefile::AddImportedTarget(const std::string& name,

Tests/RunCMake/variable_watch/RaiseInParentScope-stderr.txt

@@ -0,0 +1,2 @@
+var MODIFIED_ACCESS a
+var MODIFIED_ACCESS b

Tests/RunCMake/variable_watch/RaiseInParentScope.cmake

@@ -0,0 +1,15 @@
+
+function(watch variable access value)
+  message("${variable} ${access} ${value}")
+endfunction ()
+
+# --------------
+
+variable_watch(var watch)
+set(var "a")
+
+function(f)
+  set(var "b" PARENT_SCOPE)
+endfunction(f)
+
+f()

Tests/RunCMake/variable_watch/RunCMakeTest.cmake

@@ -4,3 +4,4 @@ run_cmake(ModifiedAccess)
 run_cmake(NoWatcher)
 run_cmake(WatchTwice)
 run_cmake(ModifyWatchInCallback)
+run_cmake(RaiseInParentScope)