[Support] Add FormatVariadic support for chrono types

Summary:
The formatter has three knobs:
- the user can choose which time unit to use for formatting (default: whatever is the unit of the input)
- he can choose whether the unit gets displayed (default: yes)
- he can affect the way the number itself is formatted via standard number formatting options (default:default)

Reviewers: zturner, inglorion

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29481

llvm-svn: 294326

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Support/Chrono.cpp b/llvm/lib/Support/Chrono.cpp
index cdadbd87997..ef81edc9269 100644
--- a/llvm/lib/Support/Chrono.cpp
+++ b/llvm/lib/Support/Chrono.cpp
@@ -16,6 +16,13 @@ namespace llvm {
 
 using namespace sys;
 
+constexpr char detail::unit<std::ratio<3600>>::value[];
+constexpr char detail::unit<std::ratio<60>>::value[];
+constexpr char detail::unit<std::ratio<1>>::value[];
+constexpr char detail::unit<std::milli>::value[];
+constexpr char detail::unit<std::micro>::value[];
+constexpr char detail::unit<std::nano>::value[];
+
 static inline struct tm getStructTM(TimePoint<> TP) {
   struct tm Storage;
   std::time_t OurTime = toTimeT(TP);