compiler: enforce structs.HostLayout usage per wasm types proposal

golang/go#66984

TODO: regenerate WASI syscall packages for GC shape types including structs.HostLayout

compiler: require go1.23 for structs.HostLayout

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"
@@ -416,14 +417,14 @@ 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()))
  }
  }
@@ -436,7 +437,7 @@ 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() {
@@ -455,19 +456,32 @@ 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
+ }
+ var hasHostLayout bool
+ if !goenv.WantGoVersion(c.pkg.GoVersion(), 1, 23) {
+ hasHostLayout = true // package structs does not exist before 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
 }