7d36d69b4a
TAIT: Infer all inference variables in opaque type substitutions via InferCx The previous algorithm was correct for the example given in its documentation, but when the TAIT was declared as a free item instead of an associated item, the generic parameters were the wrong ones. cc `@spastorino` r? `@nikomatsakis`
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.