[llvm-ar] Use POSIX-specified timestamps for 'tv'.

Summary:
The POSIX spec says:

```
If the −t option is used with the −v option, the standard output format shall be:
"%s %u/%u %u %s %d %d:%d %d %s\n", <member mode>, <user ID>,
<group ID>, <number of bytes in member>,
<abbreviated month>, <day-of-month>, <hour>,
<minute>, <year>, <file>

where:

...
<abbreviated month>
Equivalent to the format of the %b conversion specification format in date.
<day-of-month>
Equivalent to the format of the %e conversion specification format in date.
<hour> Equivalent to the format of the %H conversion specification format in date.
<minute> Equivalent to the format of the %M conversion specification format in date.
<year> Equivalent to the format of the %Y conversion specification format in date.
```

This actually used to be the format printed by llvm-ar. It was apparently accidentally changed (see r207385 followed by comments in r207387). This makes it conform to GNU ar for easier replacement.

Reviewers: MaskRay

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D52940

llvm-svn: 343901

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
index 9d2d765cdea..454b3971d28 100644
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -24,6 +24,7 @@
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -367,7 +368,11 @@ static void doDisplayTable(StringRef Name, const object::Archive::Child &C) {
     outs() << ' ' << format("%6llu", Size.get());
     auto ModTimeOrErr = C.getLastModified();
     failIfError(ModTimeOrErr.takeError());
-    outs() << ' ' << ModTimeOrErr.get();
+    // Note: formatv() only handles the default TimePoint<>, which is in
+    // nanoseconds.
+    // TODO: fix format_provider<TimePoint<>> to allow other units.
+    sys::TimePoint<> ModTimeInNs = ModTimeOrErr.get();
+    outs() << ' ' << formatv("{0:%b %e %H:%M %Y}", ModTimeInNs);
     outs() << ' ';
   }