61db6923e2
As the function comment already says, the types generated in the foreign_signture function don't necessarily match the types used for a corresponding rust function. Therefore we can't just use these types to guide the translation of the wrapper function that bridges between the external ABI and the rust ABI. Instead, we can query LLVM about the types used in the rust function and use those to generate an appropriate wrapper. Fixes #21454
See the README.txt in ../librustc.