Proposed resolution (January, 2017):

Change 9.10 [dcl.asm] paragraph 1 as follows:

An asm declaration has the form

asm-definition:
attribute-specifier-seq_opt asm ( string-literal ) ;

The asm declaration is conditionally-supported; its meaning is implementation-defined. The optional attribute-specifier-seq in an asm-definition appertains to the asm declaration. [Note: Typically it is used to pass information through the implementation to an assembler. —end note]

Notes from the December, 2016 teleconference:

The omission seems to have been an oversight that should be corrected.

[Adopted at the February/March, 2017 meeting.]

There does not seem to be a good reason not to permit attributes on an asm declaration. This would be handy for things like:

  [[vendor::asm_syntax("intel")]] asm(...);