Merge pull request #1370 from harehare/feat/mq-check-piped-self-constraint

feat(mq-check): support piped builtin calls and self keyword type propagation

Author: harehare

README.md

@@ -370,10 +370,11 @@ This makes it easy to add your own tools and workflows to `mq` without modifying
 
 The following external tools are available to extend mq's functionality:
 
-- [mq-check](https://github.com/harehare/mq-check) - A syntax and semantic checker for mq files.
+- [mq-check](https://github.com/harehare/mq/tree/main/crates/mq-check) - A syntax and semantic checker for mq files.
 - [mq-conv](https://github.com/harehare/mq-conv) - A CLI tool for converting various file formats to Markdown.
 - [mq-docs](https://github.com/harehare/mq-docs) - A documentation generator for mq functions, macros, and selectors.
 - [mq-edit](https://github.com/harehare/mq-edit) - A terminal-based Markdown and code editor with WYSIWYG rendering and LSP support.
+- [mq-lsp](https://github.com/harehare/mq/tree/main/crates/mq-lsp) - Language Server Protocol (LSP) implementation for mq query files, providing IDE features like completion, hover, and diagnostics.
 - [mq-mcp](https://github.com/harehare/mq-mcp) - Model Context Protocol (MCP) server implementation for AI assistants
 - [mq-task](https://github.com/harehare/mq-task) - Task runner using mq for Markdown-based task definitions
 - [mq-tui](https://github.com/harehare/mq-tui) - Terminal User Interface (TUI) for interactive mq query

crates/mq-check/src/constraint.rs

@@ -442,7 +442,7 @@ fn might_receive_piped_input(hir: &Hir, symbol_id: SymbolId) -> bool {
     };
     if matches!(
         parent.kind,
-        SymbolKind::Block | SymbolKind::Function(_) | SymbolKind::Macro(_)
+        SymbolKind::Block | SymbolKind::Function(_) | SymbolKind::Macro(_) | SymbolKind::Call
     ) {
         return true;
     }
@@ -2106,6 +2106,14 @@ fn generate_symbol_constraints(
                     let ty_var = ctx.fresh_var();
                     ctx.set_symbol_type(symbol_id, Type::Var(ty_var));
                 }
+            } else if symbol.is_some_and(|s| s.value.as_deref() == Some("self")) {
+                // `self` refers to the piped input value
+                if let Some(piped_ty) = ctx.get_piped_input(symbol_id).cloned() {
+                    ctx.set_symbol_type(symbol_id, piped_ty);
+                } else {
+                    let ty_var = ctx.fresh_var();
+                    ctx.set_symbol_type(symbol_id, Type::Var(ty_var));
+                }
             } else {
                 let ty_var = ctx.fresh_var();
                 ctx.set_symbol_type(symbol_id, Type::Var(ty_var));

crates/mq-check/tests/integration_test.rs

@@ -1380,3 +1380,45 @@ fn test_type_narrowing(#[case] code: &str, #[case] should_succeed: bool, #[case]
         result
     );
 }
+
+#[test]
+fn test_piped_builtin_call_in_argument_position() {
+    // Builtin calls with no explicit args used as arguments to higher-order functions
+    // should not error — the parent function will pipe each element at runtime.
+    assert!(
+        check_types("[[1,2],[3,4]] | map(first())").is_empty(),
+        "map(first()) should not error"
+    );
+    assert!(
+        check_types("[[1,2],[3,4]] | map(last())").is_empty(),
+        "map(last()) should not error"
+    );
+}
+
+#[rstest]
+#[case(r#""hello" | self | upcase()"#, "self should preserve string type for upcase", true)]
+#[case("[1,2,3] | self | first()", "self should preserve array type for first()", true)]
+#[case(
+    r#""hello" | self | sort"#,
+    "string piped through self then sort (array-only) should error",
+    false
+)]
+#[case(
+    r#""hello" | self | sort()"#,
+    "string piped through self then sort (array-only) should error",
+    false
+)]
+#[case(
+    "42 | self | sort()",
+    "number piped through self then sort (array-only) should error",
+    false
+)]
+#[case(
+    r#""hello" | upcase | sort"#,
+    "string piped through string op then sort (array-only) should error",
+    false
+)]
+fn test_self_keyword_preserves_piped_type(#[case] code: &str, #[case] description: &str, #[case] should_succeed: bool) {
+    // `self` should unify with the piped input type
+    assert_eq!(check_types(code).is_empty(), should_succeed, "{}", description);
+}