From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Mon, 31 Oct 2016 20:25:52 +0000 (+0000)
Subject: Add comment explaining this mysterious macro name.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=554e8a622237c239948213412cffc7273df3847b;p=clang

Add comment explaining this mysterious macro name.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@285631 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Frontend/InitPreprocessor.cpp b/lib/Frontend/InitPreprocessor.cpp
index 5da547e2b5..613248a7f1 100644
--- a/lib/Frontend/InitPreprocessor.cpp
+++ b/lib/Frontend/InitPreprocessor.cpp
@@ -992,6 +992,9 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   }
 
   if (TI.hasInt128Type() && LangOpts.CPlusPlus && LangOpts.GNUMode) {
+    // For each extended integer type, g++ defines a macro mapping the
+    // index of the type (0 in this case) in some list of extended types
+    // to the type.
     Builder.defineMacro("__GLIBCXX_TYPE_INT_N_0", "__int128");
     Builder.defineMacro("__GLIBCXX_BITSIZE_INT_N_0", "128");
   }