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Truly ignore //export when //go:wasmexport is used #4500

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merged 2 commits into from
Oct 5, 2024
Merged

Truly ignore //export when //go:wasmexport is used #4500

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5aaecd6
compiler: refactor pragma parsing
aykevl Oct 5, 2024
976fd3c
compiler: truly ignore //export when //go:wasmexport is used
aykevl Oct 5, 2024
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227 changes: 115 additions & 112 deletions compiler/symbol.go
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Original file line number Diff line number Diff line change
Expand Up @@ -273,129 +273,132 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
if syntax == nil {
return
}

// Read all pragmas of this function.
var pragmas []*ast.Comment
hasWasmExport := false
if decl, ok := syntax.(*ast.FuncDecl); ok && decl.Doc != nil {
for _, comment := range decl.Doc.List {
text := comment.Text
if strings.HasPrefix(text, "//export ") {
// Rewrite '//export' to '//go:export' for compatibility with
// gc.
text = "//go:" + text[2:]
if strings.HasPrefix(text, "//go:") || strings.HasPrefix(text, "//export ") {
pragmas = append(pragmas, comment)
if strings.HasPrefix(comment.Text, "//go:wasmexport ") {
hasWasmExport = true
}
}
if !strings.HasPrefix(text, "//go:") {
}
}

// Parse each pragma.
for _, comment := range pragmas {
parts := strings.Fields(comment.Text)
switch parts[0] {
case "//export", "//go:export":
if len(parts) != 2 {
continue
}
if hasWasmExport {
// //go:wasmexport overrides //export.
continue
}
parts := strings.Fields(text)
switch parts[0] {
case "//go:export":
if len(parts) != 2 {
continue
}

info.linkName = parts[1]
info.wasmName = info.linkName
info.exported = true
case "//go:interrupt":
if hasUnsafeImport(f.Pkg.Pkg) {
info.interrupt = true
}
case "//go:wasm-module":
// Alternative comment for setting the import module.
// This is deprecated, use //go:wasmimport instead.
if len(parts) != 2 {
continue
}
info.wasmModule = parts[1]
case "//go:wasmimport":
// Import a WebAssembly function, for example a WASI function.
// Original proposal: https://github.com/golang/go/issues/38248
// Allow globally: https://github.com/golang/go/issues/59149
if len(parts) != 3 {
continue
}
if f.Blocks != nil {
// Defined functions cannot be exported.
c.addError(f.Pos(), "can only use //go:wasmimport on declarations")
continue
}
c.checkWasmImportExport(f, comment.Text)
info.exported = true
info.wasmModule = parts[1]
info.wasmName = parts[2]
case "//go:wasmexport":
if f.Blocks == nil {
c.addError(f.Pos(), "can only use //go:wasmexport on definitions")
continue
}
if len(parts) != 2 {
c.addError(f.Pos(), fmt.Sprintf("expected one parameter to //go:wasmimport, not %d", len(parts)-1))
continue
}
name := parts[1]
if name == "_start" || name == "_initialize" {
c.addError(f.Pos(), fmt.Sprintf("//go:wasmexport does not allow %#v", name))
continue
}
if c.BuildMode != "c-shared" && f.RelString(nil) == "main.main" {
c.addError(f.Pos(), fmt.Sprintf("//go:wasmexport does not allow main.main to be exported with -buildmode=%s", c.BuildMode))
continue
}
if c.archFamily() != "wasm32" {
c.addError(f.Pos(), "//go:wasmexport is only supported on wasm")
}
c.checkWasmImportExport(f, comment.Text)
info.wasmExport = name
info.wasmExportPos = comment.Slash
case "//go:inline":
info.inline = inlineHint
case "//go:noinline":
info.linkName = parts[1]
info.wasmName = info.linkName
info.exported = true
case "//go:interrupt":
if hasUnsafeImport(f.Pkg.Pkg) {
info.interrupt = true
}
case "//go:wasm-module":
// Alternative comment for setting the import module.
// This is deprecated, use //go:wasmimport instead.
if len(parts) != 2 {
continue
}
info.wasmModule = parts[1]
case "//go:wasmimport":
// Import a WebAssembly function, for example a WASI function.
// Original proposal: https://github.com/golang/go/issues/38248
// Allow globally: https://github.com/golang/go/issues/59149
if len(parts) != 3 {
continue
}
if f.Blocks != nil {
// Defined functions cannot be exported.
c.addError(f.Pos(), "can only use //go:wasmimport on declarations")
continue
}
c.checkWasmImportExport(f, comment.Text)
info.exported = true
info.wasmModule = parts[1]
info.wasmName = parts[2]
case "//go:wasmexport":
if f.Blocks == nil {
c.addError(f.Pos(), "can only use //go:wasmexport on definitions")
continue
}
if len(parts) != 2 {
c.addError(f.Pos(), fmt.Sprintf("expected one parameter to //go:wasmimport, not %d", len(parts)-1))
continue
}
name := parts[1]
if name == "_start" || name == "_initialize" {
c.addError(f.Pos(), fmt.Sprintf("//go:wasmexport does not allow %#v", name))
continue
}
if c.BuildMode != "c-shared" && f.RelString(nil) == "main.main" {
c.addError(f.Pos(), fmt.Sprintf("//go:wasmexport does not allow main.main to be exported with -buildmode=%s", c.BuildMode))
continue
}
if c.archFamily() != "wasm32" {
c.addError(f.Pos(), "//go:wasmexport is only supported on wasm")
}
c.checkWasmImportExport(f, comment.Text)
info.wasmExport = name
info.wasmExportPos = comment.Slash
case "//go:inline":
info.inline = inlineHint
case "//go:noinline":
info.inline = inlineNone
case "//go:linkname":
if len(parts) != 3 || parts[1] != f.Name() {
continue
}
// Only enable go:linkname when the package imports "unsafe".
// This is a slightly looser requirement than what gc uses: gc
// requires the file to import "unsafe", not the package as a
// whole.
if hasUnsafeImport(f.Pkg.Pkg) {
info.linkName = parts[2]
}
case "//go:section":
// Only enable go:section when the package imports "unsafe".
// go:section also implies go:noinline since inlining could
// move the code to a different section than that requested.
if len(parts) == 2 && hasUnsafeImport(f.Pkg.Pkg) {
info.section = parts[1]
info.inline = inlineNone
case "//go:linkname":
if len(parts) != 3 || parts[1] != f.Name() {
continue
}
// Only enable go:linkname when the package imports "unsafe".
// This is a slightly looser requirement than what gc uses: gc
// requires the file to import "unsafe", not the package as a
// whole.
if hasUnsafeImport(f.Pkg.Pkg) {
info.linkName = parts[2]
}
case "//go:section":
// Only enable go:section when the package imports "unsafe".
// go:section also implies go:noinline since inlining could
// move the code to a different section than that requested.
if len(parts) == 2 && hasUnsafeImport(f.Pkg.Pkg) {
info.section = parts[1]
info.inline = inlineNone
}
case "//go:nobounds":
// Skip bounds checking in this function. Useful for some
// runtime functions.
// This is somewhat dangerous and thus only imported in packages
// that import unsafe.
if hasUnsafeImport(f.Pkg.Pkg) {
info.nobounds = true
}
case "//go:variadic":
// The //go:variadic pragma is emitted by the CGo preprocessing
// pass for C variadic functions. This includes both explicit
// (with ...) and implicit (no parameters in signature)
// functions.
if strings.HasPrefix(f.Name(), "C.") {
// This prefix cannot naturally be created, it must have
// been created as a result of CGo preprocessing.
info.variadic = true
}
}
case "//go:nobounds":
// Skip bounds checking in this function. Useful for some
// runtime functions.
// This is somewhat dangerous and thus only imported in packages
// that import unsafe.
if hasUnsafeImport(f.Pkg.Pkg) {
info.nobounds = true
}
case "//go:variadic":
// The //go:variadic pragma is emitted by the CGo preprocessing
// pass for C variadic functions. This includes both explicit
// (with ...) and implicit (no parameters in signature)
// functions.
if strings.HasPrefix(f.Name(), "C.") {
// This prefix cannot naturally be created, it must have
// been created as a result of CGo preprocessing.
info.variadic = true
}
}
}

// If both //go:wasmexport and //go:export or //export are declared,
// only honor go:wasmexport.
if info.wasmExport != "" {
// TODO: log warning?
info.exported = false
}
}

// Check whether this function can be used in //go:wasmimport or
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