Update the text syntax for tuple types (#6246)

Instead of e.g. `(i32 i32)`, use `(tuple i32 i32)`. Having a keyword to
introduce the s-expression is more consistent with the rest of the language.

4 files changed, 12 insertions, 9 deletions

diff --git a/src/shared-constants.h b/src/shared-constants.h
index 321ec3884..528d09df5 100644
--- a/src/shared-constants.h
+++ b/src/shared-constants.h
@@ -62,6 +62,7 @@ extern Name PRINT;
 extern Name EXIT;
 extern Name SHARED;
 extern Name TAG;
+extern Name TUPLE;
 
 } // namespace wasm
 
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index cc8fe2273..af042bd55 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -1393,12 +1393,15 @@ Type SExpressionWasmBuilder::elementToType(Element& s) {
     }
     return Type(parseHeapType(*s[i]), nullable);
   }
-  // It's a tuple.
-  std::vector<Type> types;
-  for (size_t i = 0; i < s.size(); ++i) {
-    types.push_back(elementToType(*list[i]));
+  if (elementStartsWith(s, TUPLE)) {
+    // It's a tuple.
+    std::vector<Type> types;
+    for (size_t i = 1; i < s.size(); ++i) {
+      types.push_back(elementToType(*list[i]));
+    }
+    return Type(types);
   }
-  return Type(types);
+  throw SParseException(std::string("expected type, got list"), s);
 }
 
 Type SExpressionWasmBuilder::stringToLaneType(const char* str) {
diff --git a/src/wasm/wasm-type.cpp b/src/wasm/wasm-type.cpp
index 97a8cba0e..f1ceca51a 100644
--- a/src/wasm/wasm-type.cpp
+++ b/src/wasm/wasm-type.cpp
@@ -1952,11 +1952,9 @@ std::ostream& TypePrinter::print(HeapType type) {
 }
 
 std::ostream& TypePrinter::print(const Tuple& tuple) {
-  os << '(';
-  auto sep = "";
+  os << "(tuple";
   for (Type type : tuple) {
-    os << sep;
-    sep = " ";
+    os << ' ';
     print(type);
   }
   return os << ')';
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 06e9de148..4785b22ab 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -99,6 +99,7 @@ Name PRINT("print");
 Name EXIT("exit");
 Name SHARED("shared");
 Name TAG("tag");
+Name TUPLE("tuple");
 
 // Expressions