compiler: conform to latest iteration of wasm types proposal (#4501)

compiler: align with current wasm types proposal

https://github.com/golang/go/issues/66984

- Remove int and uint as allowed types in params, results, pointers, or struct fields
- Only allow small integers in pointers, arrays, or struct fields
- enforce structs.HostLayout usage per wasm types proposal
https://github.com/golang/go/issues/66984
- require go1.23 for structs.HostLayout
- use an interface to check if GoVersion() exists
This permits TinyGo to compile with Go 1.21.
- use goenv.Compare instead of WantGoVersion
- testdata/wasmexport: use int32 instead of int
- compiler/testdata: add structs.HostLayout
- compiler/testdata: improve tests for structs.HostLayout

2 files changed, 64 insertions, 15 deletions

diff --git a/compiler/symbol.go b/compiler/symbol.go
index e175bdd78..9b9b1d10e 100644
--- a/compiler/symbol.go
+++ b/compiler/symbol.go
@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/tinygo-org/tinygo/compiler/llvmutil"
+	"github.com/tinygo-org/tinygo/goenv"
 	"github.com/tinygo-org/tinygo/loader"
 	"golang.org/x/tools/go/ssa"
 	"tinygo.org/x/go-llvm"
@@ -422,14 +423,14 @@ func (c *compilerContext) checkWasmImportExport(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(), siteResult) {
+		if !c.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(), siteParam) {
+		if !c.isValidWasmType(param.Type(), siteParam) {
 			c.addError(param.Pos(), fmt.Sprintf("%s: unsupported parameter type %s", pragma, param.Type().String()))
 		}
 	}
@@ -442,13 +443,15 @@ func (c *compilerContext) checkWasmImportExport(f *ssa.Function, pragma string)
 //
 // This previously reflected the additional restrictions documented here:
 // https://github.com/golang/go/issues/59149
-func isValidWasmType(typ types.Type, site wasmSite) bool {
+func (c *compilerContext) isValidWasmType(typ types.Type, site wasmSite) bool {
 	switch typ := typ.Underlying().(type) {
 	case *types.Basic:
 		switch typ.Kind() {
 		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:
+		case types.Int8, types.Uint8, types.Int16, types.Uint16:
+			return site == siteIndirect
+		case types.Int32, types.Uint32, types.Int64, types.Uint64:
 			return true
 		case types.Float32, types.Float64:
 			return true
@@ -459,19 +462,35 @@ func isValidWasmType(typ types.Type, site wasmSite) bool {
 			return site == siteParam || site == siteIndirect
 		}
 	case *types.Array:
-		return site == siteIndirect && isValidWasmType(typ.Elem(), siteIndirect)
+		return site == siteIndirect && c.isValidWasmType(typ.Elem(), siteIndirect)
 	case *types.Struct:
 		if site != siteIndirect {
 			return false
 		}
+		// Structs with no fields do not need structs.HostLayout
+		if typ.NumFields() == 0 {
+			return true
+		}
+		hasHostLayout := true // default to true before detecting Go version
+		// (*types.Package).GoVersion added in go1.21
+		if gv, ok := any(c.pkg).(interface{ GoVersion() string }); ok {
+			if goenv.Compare(gv.GoVersion(), "go1.23") >= 0 {
+				hasHostLayout = false // package structs added in go1.23
+			}
+		}
 		for i := 0; i < typ.NumFields(); i++ {
-			if !isValidWasmType(typ.Field(i).Type(), siteIndirect) {
+			ftyp := typ.Field(i).Type()
+			if ftyp.String() == "structs.HostLayout" {
+				hasHostLayout = true
+				continue
+			}
+			if !c.isValidWasmType(ftyp, siteIndirect) {
 				return false
 			}
 		}
-		return true
+		return hasHostLayout
 	case *types.Pointer:
-		return isValidWasmType(typ.Elem(), siteIndirect)
+		return c.isValidWasmType(typ.Elem(), siteIndirect)
 	}
 	return false
 }
diff --git a/compiler/testdata/errors.go b/compiler/testdata/errors.go
index 81e8a76a1..ae95b7523 100644
--- a/compiler/testdata/errors.go
+++ b/compiler/testdata/errors.go
@@ -1,6 +1,9 @@
 package main
 
-import "unsafe"
+import (
+	"structs"
+	"unsafe"
+)
 
 //go:wasmimport modulename empty
 func empty()
@@ -14,31 +17,37 @@ func implementation() {
 type Uint uint32
 
 type S struct {
+	_ structs.HostLayout
 	a [4]uint32
 	b uintptr
-	c int
 	d float32
 	e float64
 }
 
 //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)
+func validparam(a int32, b uint64, c float64, d unsafe.Pointer, e Uint, f uintptr, g string, h *int32, i *S, j *struct{}, k *[8]uint8)
 
 // 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 struct{a int}
 // ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type chan struct{}
 // ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type func()
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type int
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type uint
+// ERROR: //go:wasmimport modulename invalidparam: unsupported parameter type [8]int
 //
 //go:wasmimport modulename invalidparam
-func invalidparam(a [4]uint32, b []byte, c struct{ a int }, d chan struct{}, e func())
+func invalidparam(a [4]uint32, b []byte, c struct{ a int }, d chan struct{}, e func(), f int, g uint, h [8]int)
+
+// ERROR: //go:wasmimport modulename invalidparam_no_hostlayout: unsupported parameter type *struct{int}
+// ERROR: //go:wasmimport modulename invalidparam_no_hostlayout: unsupported parameter type *struct{string}
+//
+//go:wasmimport modulename invalidparam_no_hostlayout
+func invalidparam_no_hostlayout(a *struct{ int }, b *struct{ string })
 
 //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
 
@@ -48,6 +57,12 @@ func validreturn_ptr_string() *string
 //go:wasmimport modulename validreturn_ptr_struct
 func validreturn_ptr_struct() *S
 
+//go:wasmimport modulename validreturn_ptr_struct
+func validreturn_ptr_empty_struct() *struct{}
+
+//go:wasmimport modulename validreturn_ptr_array
+func validreturn_ptr_array() *[8]uint8
+
 //go:wasmimport modulename validreturn_unsafe_pointer
 func validreturn_unsafe_pointer() unsafe.Pointer
 
@@ -56,11 +71,26 @@ func validreturn_unsafe_pointer() unsafe.Pointer
 //go:wasmimport modulename manyreturns
 func manyreturns() (int32, int32)
 
+// ERROR: //go:wasmimport modulename invalidreturn_int: unsupported result type int
+//
+//go:wasmimport modulename invalidreturn_int
+func invalidreturn_int() int
+
+// ERROR: //go:wasmimport modulename invalidreturn_int: unsupported result type uint
+//
+//go:wasmimport modulename invalidreturn_int
+func invalidreturn_uint() uint
+
 // ERROR: //go:wasmimport modulename invalidreturn_func: unsupported result type func()
 //
 //go:wasmimport modulename invalidreturn_func
 func invalidreturn_func() func()
 
+// ERROR: //go:wasmimport modulename invalidreturn_pointer_array_int: unsupported result type *[8]int
+//
+//go:wasmimport modulename invalidreturn_pointer_array_int
+func invalidreturn_pointer_array_int() *[8]int
+
 // ERROR: //go:wasmimport modulename invalidreturn_slice_byte: unsupported result type []byte
 //
 //go:wasmimport modulename invalidreturn_slice_byte