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

compiler/symbol.go

@@ -273,21 +273,32 @@ 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
 			}
-			parts := strings.Fields(text)
-			switch parts[0] {
-			case "//go:export":
-				if len(parts) != 2 {
+			if hasWasmExport {
+				// //go:wasmexport overrides //export.
 				continue
 			}
 
@@ -390,14 +401,6 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 	}
 }
 
-	// 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
 // //go:wasmexport. It will add an error if this is not the case.
 //