Fix documentation and snippets for the handle attributes.

[aaron.ballman]

Thank you for fixing up the docs! As long as we're here, I suggested some extra documentation wording to make it clear what the argument is and why it's used.

clang/include/clang/Basic/AttrDocs.td

5884–5886

5907–5908

5921–5923

[paulherman]

Explaining the tag argument.

[aaron.ballman]

LGTM, thank you!

[paulherman]

Thanks for the very prompt review! I'm afraid I no longer have permissions to submit --my last commit was in 2015 and I recall that I had SVN access, but many things have changed. Would it be possible to submit this on my behalf?

[aaron.ballman]

In D108525#2960765, @paulherman wrote:

Thanks for the very prompt review! I'm afraid I no longer have permissions to submit --my last commit was in 2015 and I recall that I had SVN access, but many things have changed. Would it be possible to submit this on my behalf?

I'm happy to commit on your behalf -- what name and email address would you like me to use for patch attribution?

[paulherman]

In D108525#2960877, @aaron.ballman wrote:

In D108525#2960765, @paulherman wrote:

Thanks for the very prompt review! I'm afraid I no longer have permissions to submit --my last commit was in 2015 and I recall that I had SVN access, but many things have changed. Would it be possible to submit this on my behalf?

I'm happy to commit on your behalf -- what name and email address would you like me to use for patch attribution?

Thanks a lot! You can use "Paul Herman" as name and [e-mail] as email.

[aaron.ballman]

In D108525#2960903, @paulherman wrote:

In D108525#2960877, @aaron.ballman wrote:

In D108525#2960765, @paulherman wrote:

Thanks for the very prompt review! I'm afraid I no longer have permissions to submit --my last commit was in 2015 and I recall that I had SVN access, but many things have changed. Would it be possible to submit this on my behalf?

I'm happy to commit on your behalf -- what name and email address would you like me to use for patch attribution?

Thanks a lot! You can use "Paul Herman" as name and [e-mail] as email.

Thanks! I've commit on your behalf in f71706046144bd49af397fbed10fbe130433b969.

clang/include/clang/Basic/AttrDocs.td

 }
 
 def AcquireHandleDocs : Documentation {
   let Category = HandleDocs;
   let Content = [{
 If this annotation is on a function or a function type it is assumed to return
 a new handle. In case this annotation is on an output parameter,
 the function is assumed to fill the corresponding argument with a new
-handle.
+handle. The attribute requires a string literal argument which used to
+identify the handle with later uses of ``use_handle`` or
+``release_handle``.
 
 .. code-block:: c++
 
   // Output arguments from Zircon.
   zx_status_t zx_socket_create(uint32_t options,
-                               zx_handle_t __attribute__((acquire_handle)) * out0,
-                               zx_handle_t* out1 [[clang::acquire_handle]]);
+                               zx_handle_t __attribute__((acquire_handle("zircon"))) * out0,
+                               zx_handle_t* out1 [[clang::acquire_handle("zircon")]]);
 
 
   // Returned handle.
-  [[clang::acquire_handle]] int open(const char *path, int oflag, ... );
-  int open(const char *path, int oflag, ... ) __attribute__((acquire_handle));
+  [[clang::acquire_handle("tag")]] int open(const char *path, int oflag, ... );
+  int open(const char *path, int oflag, ... ) __attribute__((acquire_handle("tag")));
   }];
 }
 
 def UseHandleDocs : Documentation {
   let Category = HandleDocs;
   let Content = [{
 A function taking a handle by value might close the handle. If a function
-parameter is annotated with ``use_handle`` it is assumed to not to change
+parameter is annotated with ``use_handle(tag)`` it is assumed to not to change
 the state of the handle. It is also assumed to require an open handle to work with.
+The attribute requires a string literal argument to identify the handle being used.
 
 .. code-block:: c++
 
-  zx_status_t zx_port_wait(zx_handle_t handle [[clang::use_handle]],
+  zx_status_t zx_port_wait(zx_handle_t handle [[clang::use_handle("zircon")]],
                            zx_time_t deadline,
                            zx_port_packet_t* packet);
   }];
 }
 
 def ReleaseHandleDocs : Documentation {
   let Category = HandleDocs;
   let Content = [{
-If a function parameter is annotated with ``release_handle`` it is assumed to
-close the handle. It is also assumed to require an open handle to work with.
+If a function parameter is annotated with ``release_handle(tag)`` it is assumed to
+close the handle. It is also assumed to require an open handle to work with. The
+attribute requires a string literal argument to identify the handle being released.
 
 .. code-block:: c++
 
-  zx_status_t zx_handle_close(zx_handle_t handle [[clang::release_handle]]);
+  zx_status_t zx_handle_close(zx_handle_t handle [[clang::release_handle("tag")]]);
   }];
 }
 
 def ArmSveVectorBitsDocs : Documentation {
   let Category = DocCatType;
   let Content = [{
 The ``arm_sve_vector_bits(N)`` attribute is defined by the Arm C Language
 Extensions (ACLE) for SVE. It is used to define fixed-length (VLST) variants of