The parser for the Microsoft MIDL compiler has long suffered from the problem of the double greater-than sign. This problem plagued C++ until C++11 added a special rule:\u00b9<\/p>\n
[temp.names]<\/b> (4): When parsing a template-argument-list<\/i>, the first non-nested ><\/tt> is taken as the ending delimiter rather than a greater-than operator. Similarly, the first non-nested >><\/tt> is treated as two consecutive but distinct ><\/tt> tokens, the first of which is taken as the end of the template-argument-list<\/i> and completes the template-id<\/i>.<\/p><\/blockquote>\n
Microsoft’s MIDL compiler predates C++11, and its parser treats two consecutive greater-than signs as a bitwise shift operator. This means that you cannot write<\/p>\n
Windows.Foundation.IAsyncOperation<\r\n Windows.Foundation.Collections.IVector<Int32>><\/span>\r\n<\/pre>\nwhen you want an asynchronous operation that produces a vector of 32-bit integers. The double-greater-than is interpreted as a shift operator, and you get a weird MIDL error message because a shift operator is not allowed there.<\/p>\n
You must explicitly insert a space to force it to be parsed as two greater-than signs.<\/p>\n
Windows.Foundation.IAsyncOperation<\r\n Windows.Foundation.Collections.IVector<Int32> ><\/span>\r\n<\/pre>\nLarry Osterman tells me that multiple people have attempted to fix this and allow the compiler to break up a shift operator into two greater-than signs “when appropriate”.<\/p>\n
All such attempts have failed.<\/p>\n
I wonder if there is a comment in the source code similar to this legendary one<\/a>:<\/p>\n
\/\/ \r\n\/\/ Dear maintainer:\r\n\/\/ \r\n\/\/ Once you are done trying to 'optimize' this routine,\r\n\/\/ and have realized what a terrible mistake that was,\r\n\/\/ please increment the following counter as a warning\r\n\/\/ to the next guy:\r\n\/\/ \r\n\/\/ total_hours_wasted_here = 42\r\n\/\/ \r\n<\/pre>\n