Does cl_khr_integer_dot_product require OpenCL C 3.0?

I'm not sure if this is a Clang issue or an OpenCL spec issue, but I figure I'll start here.

It looks like Clang compiles OpenCL kernels that use the cl_khr_integer_dot_product extension when passed -cl-std=CL3.0, but it does not when compiling for previous OpenCL C versions.

• Here is an example that fails when compiling for OpenCL C 1.2: https://godbolt.org/z/9xPxWhPYq
• Here is the same example that succeeds when compiling for OpenCL C 3.0: https://godbolt.org/z/MWMMrWhnq

Logically speaking, this is the behavior described in the OpenCL C spec:

1. The Features section says that "Feature test macros require support for OpenCL C 3.0 or newer."
2. The new built-in functions added by cl_khr_integer_dot_product functions (e.g. dot) say "Requires that the __opencl_c_integer_dot_product_input_4x8bit feature macro is defined."

This behavior is surprising to some users, though, especially because the metadata page for cl_khr_integer_dot_product doesn't say anything about an OpenCL C 3.0 requirement. In fact, instead it says (emphasis mine): "OpenCL C compilers supporting this extension will define the extension macro cl_khr_integer_dot_product, and may define corresponding feature macros __opencl_c_integer_dot_product_input_4x8bit and __opencl_c_integer_dot_product_input_4x8bit_packed depending on the reported capabilities."

What is the intended behavior? Does cl_khr_integer_dot_product require OpenCL C 3.0?

Start with the OpenCL C 3.0 Features section and the integer dot-product built-in function requirements, then compare them with the cl_khr_integer_dot_product metadata quoted in the issue. Review the linked OpenCL C 1.2 and 3.0 compiler examples and the comment discussion. Done means the intended version and extension requirements are resolved and the relevant specification wording is clarified.