[PATCH] Use -std=c++11 when no arguments are provided.

[Ariel Bernal]

================
Comment at: docs/MigratorUsage.rst:34-40
@@ -33,9 +33,9 @@
 
   ``<build-path>`` is the directory containing a file named
   ``compile_commands.json`` which provides compiler arguments for building each
   source file. CMake can generate this file by specifying
   ``-DCMAKE_EXPORT_COMPILE_COMMANDS`` when running CMake. Ninja_, since v1.2
   can also generate this file with ``ninja -t compdb``. If ``<build-path>`` is
   not provided the ``compile_commands.json`` file is searched for through all
   parent directories.
 
----------------
Edwin Vane wrote:
> This paragraph is not quite right now. First of all, the argument is now required if `-p` is used so get rid ofthe []. Here is a suggested rewording:
> 
>   ``<build-path>`` is the directory containing a *compilation databasefile*, a file named ``compile_commands.json``, which provides 
>   compiler arguments for building each source file. CMake can generate this file by specifying
>   ``-CMAKE_EXPORT_COMPILE_COMMANDS`` when running CMake. Ninja_, since v1.2 can also generate this file with ``ninja -t
>   compdb``. If the compilation database cannot be used for any reason, an error is reported.
Yes you are right. Since we didn't add cl::ValueOptional -p should have an explicit build-path or it will take the first source location as a build path.

================
Comment at: docs/MigratorUsage.rst:50-53
@@ +49,6 @@
+
+  If ``--`` and ``-p`` are not specified then a compilation database is searched
+  based on the path of the first source file. If no compilation database is
+  found or for any reason can't be used then ``-std=c++11`` is used as the only
+  compilation option.
+
----------------
Edwin Vane wrote:
>   If *neither* ``--`` *nor* ``-p`` are specified a compilation database is searched **for** starting with the path of the first-provided source file and proceeding through parent 
>   directories. If no compilation database is found or one is found and cannot be used for any reason then ``-std=c++11`` is used as the only compiler argument.
yes much better

================
Comment at: docs/cpp11-migrate.rst:44
@@ -43,3 +43,3 @@
 arguments, it might be easier to pass the compiler args on the command line
-after ``--``. If you're working with multiple files or even a single file
-with many compiler args, it's probably best to use a *compilation database*.
+after ``--``. If you don't have any compiler argument then ``--`` is not needed.
+If you're working with multiple files or even a single file with many compiler
----------------
Edwin Vane wrote:
>   If you con't have any compiler arguments then ...
fixed.


http://llvm-reviews.chandlerc.com/D1337