From: Andrew Krieger <andrew.krieger@oculus.com>
Date: Mon, 16 Oct 2017 04:30:56 +0000 (-0700)
Subject: constexpr estimateSpaceNeeded for string literals.
X-Git-Tag: v2017.10.16.00^0
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b02d434889ac7e937aaf01b1e601c76aa119640e;p=folly.git

constexpr estimateSpaceNeeded for string literals.

Summary:
Partially inspired by WillerZ's investigation into faster compiling
StringPiece work, I thought this would be an easy drop in that short
circuits some compilation logic (or possibly is strictly better, since the
StringPiece conversion method isn't constexpr).

Reviewed By: yfeldblum

Differential Revision: D6059537

fbshipit-source-id: 072f56e58aa47db10b54825cac8a05dc035b295c
---

diff --git a/folly/Conv.h b/folly/Conv.h
index be0d3d0d..ce30765c 100644
--- a/folly/Conv.h
+++ b/folly/Conv.h
@@ -408,6 +408,11 @@ estimateSpaceNeeded(T) {
   return 1;
 }
 
+template <size_t N>
+constexpr size_t estimateSpaceNeeded(const char (&)[N]) {
+  return N;
+}
+
 /**
  * Everything implicitly convertible to const char* gets appended.
  */