Write init expressions folded so they can be parsed back

src/wat-writer.cc

@@ -1439,11 +1439,13 @@ void WatWriter::FlushExprTreeStack() {
 
 void WatWriter::WriteInitExpr(const ExprList& expr) {
   if (!expr.empty()) {
-    WritePuts("(", NextChar::None);
-    WriteExprList(expr);
+    /* Init expressions are always written folded. These positions accept a
+     * single folded expression, so wrapping a sequence of instructions in one
+     * pair of parentheses would produce output that cannot be parsed back. */
+    WriteFoldedExprList(expr);
+    FlushExprTreeStack();
     /* clear the next char, so we don't write a newline after the expr */
-    next_char_ = NextChar::None;
-    WritePuts(")", NextChar::Space);
+    next_char_ = NextChar::Space;
   }
 }
 

test/roundtrip/extended-const.txt

@@ -0,0 +1,30 @@
+;;; TOOL: run-roundtrip
+;;; ARGS: --stdout --enable-extended-const
+(module
+  (global $g_import (import "foo" "bar") i32)
+  (memory 1)
+  (table 1 funcref)
+  (func)
+  (global (mut i32) (i32.sub (i32.const 44) (i32.const 3)))
+  (global i32 (i32.const 45))
+  (data (i32.add (global.get $g_import) (i32.const 42)) "hello")
+  (elem (i32.mul (i32.const 4) (global.get $g_import)) func 0)
+)
+(;; STDOUT ;;;
+(module
+  (type (;0;) (func))
+  (import "foo" "bar" (global (;0;) i32))
+  (func (;0;) (type 0))
+  (table (;0;) 1 funcref)
+  (memory (;0;) 1)
+  (global (;1;) (mut i32) (i32.sub
+      (i32.const 44)
+      (i32.const 3)))
+  (global (;2;) i32 (i32.const 45))
+  (elem (;0;) (i32.mul
+      (i32.const 4)
+      (global.get 0)) func 0)
+  (data (;0;) (i32.add
+      (global.get 0)
+      (i32.const 42)) "hello"))
+;;; STDOUT ;;)

test/run-roundtrip.py

@@ -117,6 +117,7 @@ def main(args):
     parser.add_argument('--enable-annotations', action='store_true')
     parser.add_argument('--enable-code-metadata', action='store_true')
     parser.add_argument('--enable-custom-page-sizes', action='store_true')
+    parser.add_argument('--enable-extended-const', action='store_true')
     # --inline-exports can reorder exports, so skip roundtrip check
     parser.add_argument('--inline-exports', action='store_true',
                         help="write exports inline and skip end-to-end roundtrip check")
@@ -144,6 +145,7 @@ def main(args):
         '--enable-annotations': options.enable_annotations,
         '--enable-code-metadata': options.enable_code_metadata,
         '--enable-custom-page-sizes': options.enable_custom_page_sizes,
+        '--enable-extended-const': options.enable_extended_const,
         '--reloc': options.reloc,
         '--no-check': options.no_check,
     })
@@ -167,6 +169,7 @@ def main(args):
         '--enable-annotations': options.enable_annotations,
         '--enable-code-metadata': options.enable_code_metadata,
         '--enable-custom-page-sizes': options.enable_custom_page_sizes,
+        '--enable-extended-const': options.enable_extended_const,
         '--inline-exports': options.inline_exports,
         '--inline-imports': options.inline_imports,
         '--no-debug-names': not options.debug_names,