feat: Warn about code after return and stop generating

closes #52

CHANGELOG.md

@@ -37,6 +37,7 @@ var value = from {
 }
 ```
 - `recursive_call_limit` build option limit recursive calls (default to 200)
+- Compiler will warn about code after a `return` statement
 
 ## Changed
 - Map type notation has changed from `{K, V}` to `{K: V}`. Similarly map expression with specified typed went from `{<K, V>, ...}` to `{<K: V>, ...}` (https://github.com/buzz-language/buzz/issues/253)

src/Codegen.zig

@@ -829,8 +829,27 @@ fn generateBinary(self: *Self, node: Ast.Node.Index, breaks: ?*std.ArrayList(usi
 }
 
 fn generateBlock(self: *Self, node: Ast.Node.Index, breaks: ?*std.ArrayList(usize)) Error!?*obj.ObjFunction {
+    const tags = self.ast.nodes.items(.tag);
+
+    var seen_return = false;
     for (self.ast.nodes.items(.components)[node].Block) |statement| {
+        if (seen_return) {
+            self.reporter.warnFmt(
+                .code_after_return,
+                self.ast.tokens.get(
+                    self.ast.nodes.items(.location)[statement],
+                ),
+                "Code after return statement will never be reached",
+                .{},
+            );
+
+            // No need to generate following statements
+            break;
+        }
+
         _ = try self.generateNode(statement, breaks);
+
+        seen_return = !seen_return and tags[statement] == .Return;
     }
 
     try self.patchOptJumps(node);

src/Parser.zig

@@ -3420,7 +3420,7 @@ fn argumentList(self: *Self) ![]Ast.Call.Argument {
 }
 
 fn call(self: *Self, _: bool, callee: Ast.Node.Index) Error!Ast.Node.Index {
-    const start_location = self.current_token.? - 1;
+    const start_location = self.ast.nodes.items(.location)[callee];
     const callee_type_def = self.ast.nodes.items(.type_def)[callee];
 
     const arguments = try self.argumentList();

src/Reporter.zig

@@ -106,6 +106,7 @@ pub const Error = enum(u8) {
     inferred_type = 90,
     empty_import = 91,
     import_already_exists = 92,
+    code_after_return = 93,
 };
 
 // Inspired by https://github.com/zesterer/ariadne

tests/compile_errors/027-early-return.buzz

@@ -0,0 +1,10 @@
+| Code after return statement will never be reached
+import "std";
+
+test "Early return" {
+    print("I sure hope i'm not interrupted...");
+
+    return;
+
+    print("Guess I was");
+}