Remove named multi-return from function types

Author: lukewagner

design/mvp/Binary.md

@@ -204,7 +204,7 @@ resourcetype  ::= 0x3f 0x7f f?:<funcidx>?                 => (resource (rep i32)
 functype      ::= 0x40 ps:<paramlist> rs:<resultlist>     => (func ps rs)
 paramlist     ::= lt*:vec(<labelvaltype>)                 => (param lt)*
 resultlist    ::= 0x00 t:<valtype>                        => (result t)
-                | 0x01 lt*:vec(<labelvaltype>)            => (result lt)*
+                | 0x01 0x00                               =>
 componenttype ::= 0x41 cd*:vec(<componentdecl>)           => (component cd*)
 instancetype  ::= 0x42 id*:vec(<instancedecl>)            => (instance id*)
 componentdecl ::= 0x03 id:<importdecl>                    => id

design/mvp/Explainer.md

@@ -552,10 +552,7 @@ defvaltype    ::= bool
 valtype       ::= <typeidx>
                 | <defvaltype>
 resourcetype  ::= (resource (rep i32) (dtor async? <funcidx> (callback <funcidx>)?)?)
-functype      ::= (func <paramlist> <resultlist>)
-paramlist     ::= (param "<label>" <valtype>)*
-resultlist    ::= (result "<label>" <valtype>)*
-                | (result <valtype>)
+functype      ::= (func (param "<label>" <valtype>)* (result <valtype>)?)
 componenttype ::= (component <componentdecl>*)
 instancetype  ::= (instance <instancedecl>*)
 componentdecl ::= <importdecl>
@@ -690,13 +687,8 @@ The remaining 4 type constructors in `deftype` use `valtype` to describe
 shared-nothing functions, resources, components, and component instances:
 
 The `func` type constructor describes a component-level function definition
-that takes and returns a list of `valtype`. In contrast to [`core:functype`],
-the parameters and results of `functype` can have associated names which
-validation requires to be unique. To improve the ergonomics and performance of
-the common case of single-value-returning functions, function types may
-additionally have a single unnamed return type. For this special case, bindings
-generators are naturally encouraged to return the single value directly without
-wrapping it in any containing record/object/struct.
+that takes a list of uniquely-named `valtype` parameters and optionally returns
+a `valtype`.
 
 The `resource` type constructor creates a fresh type for each instance of the
 containing component (with "freshness" and its interaction with general

design/mvp/WIT.md

@@ -1122,7 +1122,6 @@ param-list ::= '(' named-type-list ')'
 
 result-list ::= ϵ
               | '->' ty
-              | '->' '(' named-type-list ')'
 
 named-type-list ::= ϵ
                   | named-type ( ',' named-type )*