3 files changed, 28 insertions, 7 deletions
diff --git a/lib/Basic/Diagnostic.cpp b/lib/Basic/Diagnostic.cpp
index b82b062a72..0e4159db8d 100644
--- a/lib/Basic/Diagnostic.cpp
+++ b/lib/Basic/Diagnostic.cpp
@@ -43,6 +43,7 @@ Diagnostic::Diagnostic(const llvm::IntrusiveRefCntPtr<DiagnosticIDs> &diags,
   AllExtensionsSilenced = 0;
   IgnoreAllWarnings = false;
   WarningsAsErrors = false;
+  EnableAllWarnings = false;
   ErrorsAsFatal = false;
   SuppressSystemWarnings = false;
   SuppressAllDiagnostics = false;
diff --git a/lib/Basic/DiagnosticIDs.cpp b/lib/Basic/DiagnosticIDs.cpp
index fa397c9ac9..ace92aceb4 100644
--- a/lib/Basic/DiagnosticIDs.cpp
+++ b/lib/Basic/DiagnosticIDs.cpp
@@ -496,14 +496,27 @@ DiagnosticIDs::getDiagnosticLevel(unsigned DiagID, unsigned DiagClass,
   switch (MappingInfo & 7) {
   default: assert(0 && "Unknown mapping!");
   case diag::MAP_IGNORE:
-    // Ignore this, unless this is an extension diagnostic and we're mapping
-    // them onto warnings or errors.
-    if (!isBuiltinExtensionDiag(DiagID) ||  // Not an extension
-        Diag.ExtBehavior == Diagnostic::Ext_Ignore || // Ext ignored
-        (MappingInfo & 8) != 0)             // User explicitly mapped it.
+    if (Diag.EnableAllWarnings) {
+      // Leave the warning disabled if it was explicitly ignored.
+      if ((MappingInfo & 8) != 0)
+        return DiagnosticIDs::Ignored;
+     
+      Result = Diag.WarningsAsErrors ? DiagnosticIDs::Error 
+                                     : DiagnosticIDs::Warning;
+    }
+    // Otherwise, ignore this diagnostic unless this is an extension diagnostic
+    // and we're mapping them onto warnings or errors.
+    else if (!isBuiltinExtensionDiag(DiagID) ||  // Not an extension
+             Diag.ExtBehavior == Diagnostic::Ext_Ignore || // Ext ignored
+             (MappingInfo & 8) != 0) {           // User explicitly mapped it.
       return DiagnosticIDs::Ignored;
-    Result = DiagnosticIDs::Warning;
-    if (Diag.ExtBehavior == Diagnostic::Ext_Error) Result = DiagnosticIDs::Error;
+    }
+    else {
+      Result = DiagnosticIDs::Warning;
+    }
+
+    if (Diag.ExtBehavior == Diagnostic::Ext_Error)
+      Result = DiagnosticIDs::Error;
     if (Result == DiagnosticIDs::Error && Diag.ErrorsAsFatal)
       Result = DiagnosticIDs::Fatal;
     break;
diff --git a/lib/Frontend/Warnings.cpp b/lib/Frontend/Warnings.cpp
index 215f8f8b22..d24779e1a9 100644
--- a/lib/Frontend/Warnings.cpp
+++ b/lib/Frontend/Warnings.cpp
@@ -98,6 +98,13 @@ void clang::ProcessWarningOptions(Diagnostic &Diags,
       Mapping = isPositive ? diag::MAP_ERROR : diag::MAP_WARNING_NO_WERROR;
       Opt = Specifier;
     }
+    
+    // -Weverything is a special case as well.  It implicitly enables all
+    // warnings, including ones not explicitly in a warning group.
+    if (Opt == "everything") {
+      Diags.setEnableAllWarnings(true);
+      continue;
+    }
 
     // -Wfatal-errors is yet another special case.
     if (Opt.startswith("fatal-errors")) {