wasi preview 2 support (#4027)

* all: wasip2 support

Co-authored-by: Randy Reddig <randy.reddig@fastly.com>

compiler/symbol.go

@@ -346,7 +346,7 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 // The list of allowed types is based on this proposal:
 // https://github.com/golang/go/issues/59149
 func (c *compilerContext) checkWasmImport(f *ssa.Function, pragma string) {
-	if c.pkg.Path() == "runtime" || c.pkg.Path() == "syscall/js" {
+	if c.pkg.Path() == "runtime" || c.pkg.Path() == "syscall/js" || c.pkg.Path() == "syscall" {
 		// The runtime is a special case. Allow all kinds of parameters
 		// (importantly, including pointers).
 		return
@@ -360,38 +360,68 @@ func (c *compilerContext) checkWasmImport(f *ssa.Function, pragma string) {
 		c.addError(f.Signature.Results().At(1).Pos(), fmt.Sprintf("%s: too many return values", pragma))
 	} else if f.Signature.Results().Len() == 1 {
 		result := f.Signature.Results().At(0)
-		if !isValidWasmType(result.Type(), true) {
+		if !isValidWasmType(result.Type(), siteResult) {
 			c.addError(result.Pos(), fmt.Sprintf("%s: unsupported result type %s", pragma, result.Type().String()))
 		}
 	}
 	for _, param := range f.Params {
 		// Check whether the type is allowed.
 		// Only a very limited number of types can be mapped to WebAssembly.
-		if !isValidWasmType(param.Type(), false) {
+		if !isValidWasmType(param.Type(), siteParam) {
 			c.addError(param.Pos(), fmt.Sprintf("%s: unsupported parameter type %s", pragma, param.Type().String()))
 		}
 	}
 }
 
-// Check whether the type maps directly to a WebAssembly type, according to:
+// Check whether the type maps directly to a WebAssembly type.
+//
+// This reflects the relaxed type restrictions proposed here (except for structs.HostLayout):
+// https://github.com/golang/go/issues/66984
+//
+// This previously reflected the additional restrictions documented here:
 // https://github.com/golang/go/issues/59149
-func isValidWasmType(typ types.Type, isReturn bool) bool {
+func isValidWasmType(typ types.Type, site wasmSite) bool {
 	switch typ := typ.Underlying().(type) {
 	case *types.Basic:
 		switch typ.Kind() {
-		case types.Int32, types.Uint32, types.Int64, types.Uint64:
+		case types.Bool:
+			return true
+		case types.Int, types.Uint, types.Int8, types.Uint8, types.Int16, types.Uint16, types.Int32, types.Uint32, types.Int64, types.Uint64:
 			return true
 		case types.Float32, types.Float64:
 			return true
-		case types.UnsafePointer:
-			if !isReturn {
-				return true
+		case types.Uintptr, types.UnsafePointer:
+			return true
+		case types.String:
+			// string flattens to two values, so disallowed as a result
+			return site == siteParam || site == siteIndirect
+		}
+	case *types.Array:
+		return site == siteIndirect && isValidWasmType(typ.Elem(), siteIndirect)
+	case *types.Struct:
+		if site != siteIndirect {
+			return false
+		}
+		for i := 0; i < typ.NumFields(); i++ {
+			if !isValidWasmType(typ.Field(i).Type(), siteIndirect) {
+				return false
 			}
 		}
+		return true
+	case *types.Pointer:
+		return isValidWasmType(typ.Elem(), siteIndirect)
 	}
 	return false
 }
 
+type wasmSite int
+
+const (
+	siteParam wasmSite = iota
+	siteResult
+	siteIndirect // pointer or field
+)
+
 // getParams returns the function parameters, including the receiver at the
 // start. This is an alternative to the Params member of *ssa.Function, which is
 // not yet populated when the package has not yet been built.

compiler/testdata/errors.go

@@ -13,31 +13,65 @@ func implementation() {
 
 type Uint uint32
 
-//go:wasmimport modulename validparam
-func validparam(a int32, b uint64, c float64, d unsafe.Pointer, e Uint)
+type S struct {
+	a [4]uint32
+	b uintptr
+	c int
+	d float32
+	e float64
+}
 
-// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type int
-// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type string
+//go:wasmimport modulename validparam
+func validparam(a int32, b uint64, c float64, d unsafe.Pointer, e Uint, f uintptr, g string, h *int32, i *S)
+
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type [4]uint32
 // ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type []byte
-// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type *int32
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type struct{a int}
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type chan struct{}
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type func()
 //
 //go:wasmimport modulename invalidparam
-func invalidparam(a int, b string, c []byte, d *int32)
+func invalidparam(a [4]uint32, b []byte, c struct{ a int }, d chan struct{}, e func())
 
-//go:wasmimport modulename validreturn
-func validreturn() int32
+//go:wasmimport modulename validreturn_int32
+func validreturn_int32() int32
+
+//go:wasmimport modulename validreturn_int
+func validreturn_int() int
+
+//go:wasmimport modulename validreturn_ptr_int32
+func validreturn_ptr_int32() *int32
+
+//go:wasmimport modulename validreturn_ptr_string
+func validreturn_ptr_string() *string
+
+//go:wasmimport modulename validreturn_ptr_struct
+func validreturn_ptr_struct() *S
+
+//go:wasmimport modulename validreturn_unsafe_pointer
+func validreturn_unsafe_pointer() unsafe.Pointer
 
 // ERROR: //go:wasmimport modulename manyreturns: too many return values
 //
 //go:wasmimport modulename manyreturns
 func manyreturns() (int32, int32)
 
-// ERROR: //go:wasmimport modulename invalidreturn: unsupported result type int
+// ERROR: //go:wasmimport modulename invalidreturn_func: unsupported result type func()
 //
-//go:wasmimport modulename invalidreturn
-func invalidreturn() int
+//go:wasmimport modulename invalidreturn_func
+func invalidreturn_func() func()
 
-// ERROR: //go:wasmimport modulename invalidUnsafePointerReturn: unsupported result type unsafe.Pointer
+// ERROR: //go:wasmimport modulename invalidreturn_slice_byte: unsupported result type []byte
 //
-//go:wasmimport modulename invalidUnsafePointerReturn
-func invalidUnsafePointerReturn() unsafe.Pointer
+//go:wasmimport modulename invalidreturn_slice_byte
+func invalidreturn_slice_byte() []byte
+
+// ERROR: //go:wasmimport modulename invalidreturn_chan_int: unsupported result type chan int
+//
+//go:wasmimport modulename invalidreturn_chan_int
+func invalidreturn_chan_int() chan int
+
+// ERROR: //go:wasmimport modulename invalidreturn_string: unsupported result type string
+//
+//go:wasmimport modulename invalidreturn_string
+func invalidreturn_string() string