Document -std= values for different languages

Summary:
After a remark on a FreeBSD mailing list that the clang man page did
not have any list of possible values for the `-std=` flag, I have now
attempted to exhaustively list those, for each available language.

I also documented the default standard for each language, if there was
more than one choice.

Reviewers: rsmith, dexonsmith, sylvestre.ledru, mgorny

Reviewed By: rsmith

Subscribers: fhahn, emaste, cfe-commits, krytarowski

Differential Revision: https://reviews.llvm.org/D45406

llvm-svn: 329827

1 files changed, 120 insertions, 1 deletions

diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst
index 16bb09f3c74..d440d915d68 100644
--- a/clang/docs/CommandGuide/clang.rst
+++ b/clang/docs/CommandGuide/clang.rst
@@ -98,10 +98,129 @@ Language Selection and Mode Options
 
  Treat subsequent input files as having type language.
 
-.. option:: -std=<language>
+.. option:: -std=<standard>
 
  Specify the language standard to compile for.
 
+ Supported values for the C language are:
+
+  | ``c89``
+  | ``c90``
+  | ``iso9899:1990``
+
+   ISO C 1990
+
+  | ``iso9899:199409``
+
+   ISO C 1990 with amendment 1
+
+  | ``gnu89``
+  | ``gnu90``
+
+   ISO C 1990 with GNU extensions
+
+  | ``c99``
+  | ``iso9899:1999``
+
+   ISO C 1999
+
+  | ``gnu99``
+
+   ISO C 1999 with GNU extensions
+
+  | ``c11``
+  | ``iso9899:2011``
+
+   ISO C 2011
+
+  | ``gnu11``
+
+   ISO C 2011 with GNU extensions
+
+  | ``c17``
+  | ``iso9899:2017``
+
+   ISO C 2017
+
+  | ``gnu17``
+
+   ISO C 2017 with GNU extensions
+
+ The default C language standard is ``gnu11``, except on PS4, where it is
+ ``gnu99``.
+
+ Supported values for the C++ language are:
+
+  | ``c++98``
+  | ``c++03``
+
+   ISO C++ 1998 with amendments
+
+  | ``gnu++98``
+  | ``gnu++03``
+
+   ISO C++ 1998 with amendments and GNU extensions
+
+  | ``c++11``
+
+   ISO C++ 2011 with amendments
+
+  | ``gnu++11``
+
+    ISO C++ 2011 with amendments and GNU extensions
+
+  | ``c++14``
+
+   ISO C++ 2014 with amendments
+
+  | ``gnu++14``
+
+   ISO C++ 2014 with amendments and GNU extensions
+
+  | ``c++17``
+
+   ISO C++ 2017 with amendments
+
+  | ``gnu++17``
+
+   ISO C++ 2017 with amendments and GNU extensions
+
+  | ``c++2a``
+
+   Working draft for ISO C++ 2020
+
+  | ``gnu++2a``
+
+   Working draft for ISO C++ 2020 with GNU extensions
+
+ The default C++ language standard is ``gnu++14``.
+
+ Supported values for the OpenCL language are:
+
+  | ``cl1.0``
+
+   OpenCL 1.0
+
+  | ``cl1.1``
+
+   OpenCL 1.1
+
+  | ``cl1.2``
+
+   OpenCL 1.2
+
+  | ``cl2.0``
+
+   OpenCL 2.0
+
+ The default OpenCL language standard is ``cl1.0``.
+
+ Supported values for the CUDA language are:
+
+  | ``cuda``
+
+   NVIDIA CUDA(tm)
+
 .. option:: -stdlib=<library>
 
  Specify the C++ standard library to use; supported options are libstdc++ and