Explicitly enable author (dev) warnings by default.

Explicitly enable author warnings by default, via the
cmake::GetSuppressDevWarnings method, which signals suppression
is turned off unless the CMake variables are set as required.

Add test cases for author and deprecated messages displayed by
default.

Source/cmMessageCommand.cxx

@@ -43,7 +43,8 @@ bool cmMessageCommand
     }
   else if (*i == "AUTHOR_WARNING")
     {
-    if (this->Makefile->IsOn("CMAKE_SUPPRESS_DEVELOPER_WARNINGS"))
+    if (this->Makefile->GetCMakeInstance()->GetSuppressDevWarnings(
+        this->Makefile))
       {
       return true;
       }

Source/cmake.cxx

@@ -1580,6 +1580,7 @@ int cmake::Run(const std::vector<std::string>& args, bool noconfigure)
     {
     this->AddCMakePaths();
     }
+
   // Add any cache args
   if ( !this->SetCacheArgs(args) )
     {
@@ -2511,11 +2512,7 @@ bool cmake::IsMessageTypeVisible(cmake::MessageType t)
     }
   else if (t == cmake::AUTHOR_WARNING)
     {
-    // if CMAKE_SUPPRESS_DEVELOPER_WARNINGS is on, suppress the message,
-    // otherwise show it
-    const char* suppressDevWarnings = this->State->GetCacheEntryValue(
-                                          "CMAKE_SUPPRESS_DEVELOPER_WARNINGS");
-    if(cmSystemTools::IsOn(suppressDevWarnings))
+    if (this->GetSuppressDevWarnings())
       {
       isVisible = false;
       }
@@ -2807,3 +2804,21 @@ void cmake::RunCheckForUnusedVariables()
     }
 #endif
 }
+
+bool cmake::GetSuppressDevWarnings(cmMakefile const* mf)
+{
+  /*
+   * The suppression CMake variable may be set in the CMake configuration file
+   * itself, so we have to check what its set to in the makefile if we can.
+   */
+  if (mf)
+    {
+    return mf->IsOn("CMAKE_SUPPRESS_DEVELOPER_WARNINGS");
+    }
+  else
+    {
+    const char* cacheEntryValue = this->State->GetCacheEntryValue(
+      "CMAKE_SUPPRESS_DEVELOPER_WARNINGS");
+    return cmSystemTools::IsOn(cacheEntryValue);
+    }
+}

Source/cmake.h

@@ -308,6 +308,12 @@ class cmake
       this->SuppressDevWarnings = v;
       this->DoSuppressDevWarnings = true;
     }
+  /*
+   * Get the state of the suppression of developer (author) warnings.
+   * Returns false, by default, if developer warnings should be shown, true
+   * otherwise.
+   */
+  bool GetSuppressDevWarnings(cmMakefile const* mf = NULL);
 
   /** Display a message to the user.  */
   void IssueMessage(cmake::MessageType t, std::string const& text,