What is the state of C99 support in major compilers / toolchains?

Question

A response to a comment I made here made me stop and think: "I don't really know what the state of C99 support is."

Wikipedia gives details for a few compilers, but I'm not familiar enough with C99 to know all the bits and pieces of the standard, so I'm looking for a gestalt overview answer to the question:

What is the state of C99 support in major compilers / toolchains?

Answer 1

1. MSVC: Intentionally not implemented unless it overlaps with C++
2. GCC: Most of the useful parts are in (and have been for awhile). Some missing features.
3. clang: Claims full C99 support