fix: block ends with expr stmt

batch_run.py

@@ -2,36 +2,38 @@ import os
 import asyncio
 
 
-async def check_file(filepath):
+async def check_file(in_path, out_path):
     proc = await asyncio.create_subprocess_exec(
         "moon",
         "run",
         "src/bin/main.mbt",
         "--",
-        "--typecheck",
-        filepath,
+        in_path,
+        "-o",
+        out_path,
         stdout=asyncio.subprocess.PIPE,
         stderr=asyncio.subprocess.PIPE,
     )
     stdout, stderr = await proc.communicate()
     if proc.returncode != 0:
         print(f"""
-[{proc.returncode}] Error in file {filepath}:
+[{proc.returncode}] Error in file {in_path}:
 ======== STDOUT ========
 {stdout.decode()}
 ======== STDERR ========
 {stderr.decode()}
 """)
     else:
-        print(f"File {filepath} compiled successfully.")
+        print(f"File {in_path} compiled successfully.")
 
 
 async def main():
     tasks = []
     for file in os.listdir("contest-2025-data/test_cases/mbt"):
         if file.endswith(".mbt"):
-            filepath = os.path.join("contest-2025-data/test_cases/mbt", file)
-            tasks.append(check_file(filepath))
+            in_path = os.path.join("contest-2025-data/test_cases/mbt", file)
+            out_path = os.path.join("output/repo", file.replace(".mbt", ".s"))
+            tasks.append(check_file(in_path, out_path))
     await asyncio.gather(*tasks)
 
 

src/parser/ast.mbt

@@ -485,7 +485,12 @@ pub fn parse_block_expr(
         }
         break r
       } else if r is [RCurlyBracket, .. r] {
-        stmts.push(Expr(Literal(Unit)))
+        // Ref: syntax.typ:123-125
+        // - 一个Block 块可以有返回值，块内的最后一条语句可以是一个expr，也可以是一个`stmt`，如果块的最后一个语句是一个`expr`，则该块的值就是这个 `expr` 的值。如果块的最后一个语句是一个 `stmt`，且这个块是一个`expr_stmt`，则该块的值就是这个 `stmt` 的值。
+        // 例如， ```rust let a = 1; { let b = 2; a + b }``` 的值是 `3`，```rust let a = 1; { let b = 2; a + b; }``` 的值是 `3`，而```rust let a = 1; { let b = 2; let _ = a + b; }``` 的值是 `()`。
+        if !(stmts is [.., Expr(_)]) {
+          stmts.push(Expr(Literal(Unit)))
+        }
         break r
       }
       continue r

src/parser/ast_wbtest.mbt

@@ -154,7 +154,7 @@ test "parse_block_expr" {
       RCurlyBracket,
       EOF,
     ]),
-    content="(Block([Expr(Literal(Int(1))), Expr(Literal(Unit))]), [EOF])",
+    content="(Block([Expr(Literal(Int(1)))]), [EOF])",
   )
 }
 
@@ -226,7 +226,7 @@ test "parse_if_level_expr" {
       RCurlyBracket,
       EOF,
     ]),
-    content="(If(Literal(Int(0)), Block([Expr(Literal(Int(1))), Expr(Literal(Unit))]), None), [EOF])",
+    content="(If(Literal(Int(0)), Block([Expr(Literal(Int(1)))]), None), [EOF])",
   )
 }
 
@@ -333,6 +333,8 @@ test "parse_program" {
       LCurlyBracket,
       IntLiteral(0),
       Semicolon,
+      LParen,
+      RParen,
       RCurlyBracket,
       EOF,
     ]),

src/typecheck/typecheck_test.mbt

@@ -563,7 +563,7 @@ test "Block Expr TypeCheck Test" {
   // TypeCheck first block expr
   let (block_expr1, tok_view) = @parser.parse_block_expr(tok_view)
   let checked_block1 = ctx.check_block_expr(block_expr1)
-  assert_true(checked_block1.stmts.length() is 5) // Lilunar adds an implicit Expr(Unit) at the end
+  assert_true(checked_block1.stmts.length() is 4)
   assert_true(checked_block1.ty is Unit)
   // TypeCheck second block expr
   let (block_expr2, tok_view) = @parser.parse_block_expr(tok_view)