Add cmake_language(GET_MESSAGE_LOG_LEVEL) sub command

The new sub-command writes a string representation of the
current log level to the output variable given to the
sub-command.

Given that the log-level might be set either via the --log-level
command line option or via the CMAKE_MESSAGE_LOG_LEVEL
cache / regular variables, the priority for each of the log level
sources is as follows, with the first one being the highest:
1) --log-level
2) CMAKE_MESSAGE_LOG_LEVEL regular variable
3) CMAKE_MESSAGE_LOG_LEVEL cache variable
4) default log level (STATUS)

Fixes: #23572

1 files changed, 23 insertions, 0 deletions

diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 97a3db9..62ea427 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -149,6 +149,29 @@ void cmMakefile::IssueMessage(MessageType t, std::string const& text) const
   this->GetCMakeInstance()->IssueMessage(t, text, this->Backtrace);
 }
 
+Message::LogLevel cmMakefile::GetCurrentLogLevel() const
+{
+  const cmake* cmakeInstance = this->GetCMakeInstance();
+
+  const Message::LogLevel logLevelCliOrDefault = cmakeInstance->GetLogLevel();
+  assert("Expected a valid log level here" &&
+         logLevelCliOrDefault != Message::LogLevel::LOG_UNDEFINED);
+
+  Message::LogLevel result = logLevelCliOrDefault;
+
+  // If the log-level was set via the command line option, it takes precedence
+  // over the CMAKE_MESSAGE_LOG_LEVEL variable.
+  if (!cmakeInstance->WasLogLevelSetViaCLI()) {
+    const Message::LogLevel logLevelFromVar = cmake::StringToLogLevel(
+      this->GetSafeDefinition("CMAKE_MESSAGE_LOG_LEVEL"));
+    if (logLevelFromVar != Message::LogLevel::LOG_UNDEFINED) {
+      result = logLevelFromVar;
+    }
+  }
+
+  return result;
+}
+
 bool cmMakefile::CheckCMP0037(std::string const& targetName,
                               cmStateEnums::TargetType targetType) const
 {