https://issues.dlang.org/show_bug.cgi?id=13308

          Issue ID: 13308
           Summary: AsmPrimaryExp documentation is incorrect
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: websites
          Assignee: nobody@puremagic.com
          Reporter: briancschott@gmail.com

AsmPrimaryExp:
    IntegerLiteral
    FloatLiteral
    __LOCAL_SIZE
    $
    Register
    Register64
    DotIdentifier

This grammar says nothing about segment overrides. (i.e. ":" being a valid token in a primary expression.)

According to the spec this line in druntime's thread.d is invalid:

asm { naked; mov EAX, FS:4; ret; }

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