Implement `Function` constructor (#2090)

This Pull Request changes the following:

- Implement `Function` constructor
- Ignore non-standard `caller` feature in 262 tests
- Fix `Function.apply` length
- Use `TypeError` in `Function.caller` and `Function.arguments` accessors

boa_engine/src/builtins/error/type.rs

@@ -96,7 +96,7 @@ impl TypeError {
 
 pub(crate) fn create_throw_type_error(context: &mut Context) -> JsObject {
     fn throw_type_error(_: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
-        context.throw_type_error("invalid type")
+        context.throw_type_error("'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them")
     }
 
     let function = JsObject::from_proto_and_data(

boa_engine/src/builtins/function/mod.rs

@@ -22,10 +22,12 @@ use crate::{
     object::{ConstructorBuilder, FunctionBuilder, Ref, RefMut},
     property::{Attribute, PropertyDescriptor, PropertyKey},
     symbol::WellKnownSymbols,
+    syntax::{ast::node::FormalParameterList, Parser},
     value::IntegerOrInfinity,
     Context, JsResult, JsString, JsValue,
 };
 use boa_gc::{self, Finalize, Gc, Trace};
+use boa_interner::Sym;
 use boa_profiler::Profiler;
 use dyn_clone::DynClone;
 use std::{
@@ -275,23 +277,152 @@ pub struct BuiltInFunctionObject;
 impl BuiltInFunctionObject {
     pub const LENGTH: usize = 1;
 
+    /// `Function ( p1, p2, … , pn, body )`
+    ///
+    /// The apply() method invokes self with the first argument as the `this` value
+    /// and the rest of the arguments provided as an array (or an array-like object).
+    ///
+    /// More information:
+    ///  - [MDN documentation][mdn]
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-function-p1-p2-pn-body
+    /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/Function
     fn constructor(
         new_target: &JsValue,
-        _: &[JsValue],
+        args: &[JsValue],
         context: &mut Context,
     ) -> JsResult<JsValue> {
+        Self::create_dynamic_function(new_target, args, context).map(Into::into)
+    }
+
+    /// `CreateDynamicFunction ( constructor, newTarget, kind, args )`
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-createdynamicfunction
+    fn create_dynamic_function(
+        new_target: &JsValue,
+        args: &[JsValue],
+        context: &mut Context,
+    ) -> JsResult<JsObject> {
         let prototype =
             get_prototype_from_constructor(new_target, StandardConstructors::function, context)?;
+        if let Some((body_arg, args)) = args.split_last() {
+            let parameters =
+                if args.is_empty() {
+                    FormalParameterList::empty()
+                } else {
+                    let mut parameters = Vec::with_capacity(args.len());
+                    for arg in args {
+                        parameters.push(arg.to_string(context)?);
+                    }
+                    let mut parameters = parameters.join(",");
+                    parameters.push(')');
+
+                    let parameters = match Parser::new(parameters.as_bytes())
+                        .parse_formal_parameters(context.interner_mut(), false, false)
+                    {
+                        Ok(parameters) => parameters,
+                        Err(e) => {
+                            return context.throw_syntax_error(format!(
+                                "failed to parse function parameters: {e}"
+                            ))
+                        }
+                    };
+                    parameters
+                };
+
+            let body_arg = body_arg.to_string(context)?;
+
+            let body = match Parser::new(body_arg.as_bytes()).parse_function_body(
+                context.interner_mut(),
+                false,
+                false,
+            ) {
+                Ok(statement_list) => statement_list,
+                Err(e) => {
+                    return context
+                        .throw_syntax_error(format!("failed to parse function body: {e}"))
+                }
+            };
+
+            // Early Error: If BindingIdentifier is present and the source text matched by BindingIdentifier is strict mode code,
+            // it is a Syntax Error if the StringValue of BindingIdentifier is "eval" or "arguments".
+            if body.strict() {
+                for parameter in parameters.parameters.iter() {
+                    for name in parameter.names() {
+                        if name == Sym::ARGUMENTS || name == Sym::EVAL {
+                            return context.throw_syntax_error(
+                                " Unexpected 'eval' or 'arguments' in strict mode",
+                            );
+                        }
+                    }
+                }
+            }
+
+            // Early Error: If the source code matching FormalParameters is strict mode code,
+            // the Early Error rules for UniqueFormalParameters : FormalParameters are applied.
+            if (body.strict()) && parameters.has_duplicates() {
+                return context
+                    .throw_syntax_error("Duplicate parameter name not allowed in this context");
+            }
+
+            // Early Error: It is a Syntax Error if FunctionBodyContainsUseStrict of GeneratorBody is true
+            // and IsSimpleParameterList of FormalParameters is false.
+            if body.strict() && !parameters.is_simple() {
+                return context.throw_syntax_error(
+                    "Illegal 'use strict' directive in function with non-simple parameter list",
+                );
+            }
 
-        let this = JsObject::from_proto_and_data(
-            prototype,
-            ObjectData::function(Function::Native {
-                function: |_, _, _| Ok(JsValue::undefined()),
-                constructor: true,
-            }),
-        );
+            // It is a Syntax Error if any element of the BoundNames of FormalParameters
+            // also occurs in the LexicallyDeclaredNames of FunctionBody.
+            // https://tc39.es/ecma262/#sec-function-definitions-static-semantics-early-errors
+            {
+                let lexically_declared_names = body.lexically_declared_names();
+                for param in parameters.parameters.as_ref() {
+                    for param_name in param.names() {
+                        if lexically_declared_names
+                            .iter()
+                            .any(|(name, _)| *name == param_name)
+                        {
+                            return context.throw_syntax_error(format!(
+                                "Redeclaration of formal parameter `{}`",
+                                context.interner().resolve_expect(param_name)
+                            ));
+                        }
+                    }
+                }
+            }
 
-        Ok(this.into())
+            let code = crate::bytecompiler::ByteCompiler::compile_function_code(
+                crate::bytecompiler::FunctionKind::Expression,
+                Some(Sym::EMPTY_STRING),
+                &parameters,
+                &body,
+                false,
+                false,
+                context,
+            )?;
+
+            let environments = context.realm.environments.pop_to_global();
+            let function_object = crate::vm::create_function_object(code, context);
+            context.realm.environments.extend(environments);
+
+            Ok(function_object)
+        } else {
+            let this = JsObject::from_proto_and_data(
+                prototype,
+                ObjectData::function(Function::Native {
+                    function: |_, _, _| Ok(JsValue::undefined()),
+                    constructor: true,
+                }),
+            );
+
+            Ok(this)
+        }
     }
 
     /// `Function.prototype.apply ( thisArg, argArray )`
@@ -523,6 +654,8 @@ impl BuiltIn for BuiltInFunctionObject {
             .constructor(false)
             .build();
 
+        let throw_type_error = context.intrinsics().objects().throw_type_error();
+
         ConstructorBuilder::with_standard_constructor(
             context,
             Self::constructor,
@@ -530,11 +663,27 @@ impl BuiltIn for BuiltInFunctionObject {
         )
         .name(Self::NAME)
         .length(Self::LENGTH)
-        .method(Self::apply, "apply", 1)
+        .method(Self::apply, "apply", 2)
         .method(Self::bind, "bind", 1)
         .method(Self::call, "call", 1)
         .method(Self::to_string, "toString", 0)
         .property(symbol_has_instance, has_instance, Attribute::default())
+        .property_descriptor(
+            "caller",
+            PropertyDescriptor::builder()
+                .get(throw_type_error.clone())
+                .set(throw_type_error.clone())
+                .enumerable(false)
+                .configurable(true),
+        )
+        .property_descriptor(
+            "arguments",
+            PropertyDescriptor::builder()
+                .get(throw_type_error.clone())
+                .set(throw_type_error)
+                .enumerable(false)
+                .configurable(true),
+        )
         .build()
         .conv::<JsValue>()
         .pipe(Some)

boa_engine/src/bytecompiler.rs

@@ -11,7 +11,7 @@ use crate::{
             object::{MethodDefinition, PropertyDefinition, PropertyName},
             operator::assign::AssignTarget,
             template::TemplateElement,
-            Class, Declaration, GetConstField, GetField,
+            Class, Declaration, FormalParameterList, GetConstField, GetField, StatementList,
         },
         op::{AssignOp, BinOp, BitOp, CompOp, LogOp, NumOp, UnaryOp},
         Const, Node,
@@ -1866,54 +1866,17 @@ impl<'b> ByteCompiler<'b> {
         Ok(())
     }
 
-    pub(crate) fn function(&mut self, function: &Node, use_expr: bool) -> JsResult<()> {
-        #[derive(Debug, Clone, Copy, PartialEq)]
-        enum FunctionKind {
-            Declaration,
-            Expression,
-            Arrow,
-        }
-
-        let (kind, name, parameters, body, generator) = match function {
-            Node::FunctionDecl(function) => (
-                FunctionKind::Declaration,
-                Some(function.name()),
-                function.parameters(),
-                function.body(),
-                false,
-            ),
-            Node::GeneratorDecl(generator) => (
-                FunctionKind::Declaration,
-                Some(generator.name()),
-                generator.parameters(),
-                generator.body(),
-                true,
-            ),
-            Node::FunctionExpr(function) => (
-                FunctionKind::Expression,
-                function.name(),
-                function.parameters(),
-                function.body(),
-                false,
-            ),
-            Node::GeneratorExpr(generator) => (
-                FunctionKind::Expression,
-                generator.name(),
-                generator.parameters(),
-                generator.body(),
-                true,
-            ),
-            Node::ArrowFunctionDecl(function) => (
-                FunctionKind::Arrow,
-                function.name(),
-                function.params(),
-                function.body(),
-                false,
-            ),
-            _ => unreachable!(),
-        };
-
-        let strict = body.strict() || self.code_block.strict;
+    /// Compile a function statement list and it's parameters into bytecode.
+    pub(crate) fn compile_function_code(
+        kind: FunctionKind,
+        name: Option<Sym>,
+        parameters: &FormalParameterList,
+        body: &StatementList,
+        generator: bool,
+        strict: bool,
+        context: &mut Context,
+    ) -> JsResult<Gc<CodeBlock>> {
+        let strict = strict || body.strict();
         let length = parameters.length();
         let mut code = CodeBlock::new(name.unwrap_or(Sym::EMPTY_STRING), length, strict, true);
 
@@ -1932,7 +1895,7 @@ impl<'b> ByteCompiler<'b> {
             names_map: FxHashMap::default(),
             bindings_map: FxHashMap::default(),
             jump_info: Vec::new(),
-            context: self.context,
+            context,
         };
 
         compiler.context.push_compile_time_environment(true);
@@ -2023,7 +1986,59 @@ impl<'b> ByteCompiler<'b> {
         compiler.emit(Opcode::PushUndefined, &[]);
         compiler.emit(Opcode::Return, &[]);
 
-        let code = Gc::new(compiler.finish());
+        Ok(Gc::new(compiler.finish()))
+    }
+
+    /// Compile a function AST Node into bytecode.
+    pub(crate) fn function(&mut self, function: &Node, use_expr: bool) -> JsResult<()> {
+        let (kind, name, parameters, body, generator) = match function {
+            Node::FunctionDecl(function) => (
+                FunctionKind::Declaration,
+                Some(function.name()),
+                function.parameters(),
+                function.body(),
+                false,
+            ),
+            Node::GeneratorDecl(generator) => (
+                FunctionKind::Declaration,
+                Some(generator.name()),
+                generator.parameters(),
+                generator.body(),
+                true,
+            ),
+            Node::FunctionExpr(function) => (
+                FunctionKind::Expression,
+                function.name(),
+                function.parameters(),
+                function.body(),
+                false,
+            ),
+            Node::GeneratorExpr(generator) => (
+                FunctionKind::Expression,
+                generator.name(),
+                generator.parameters(),
+                generator.body(),
+                true,
+            ),
+            Node::ArrowFunctionDecl(function) => (
+                FunctionKind::Arrow,
+                function.name(),
+                function.params(),
+                function.body(),
+                false,
+            ),
+            _ => unreachable!(),
+        };
+
+        let code = Self::compile_function_code(
+            kind,
+            name,
+            parameters,
+            body,
+            generator,
+            self.code_block.strict,
+            self.context,
+        )?;
 
         let index = self.code_block.functions.len() as u32;
         self.code_block.functions.push(code);
@@ -2906,3 +2921,11 @@ impl<'b> ByteCompiler<'b> {
         Ok(())
     }
 }
+
+/// `FunctionKind` describes how a function has been defined in the source code.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub(crate) enum FunctionKind {
+    Declaration,
+    Expression,
+    Arrow,
+}

boa_engine/src/syntax/parser/mod.rs

@@ -13,9 +13,15 @@ mod tests;
 
 use crate::{
     syntax::{
-        ast::{node::StatementList, Position},
+        ast::{
+            node::{FormalParameterList, StatementList},
+            Position,
+        },
         lexer::TokenKind,
-        parser::cursor::Cursor,
+        parser::{
+            cursor::Cursor,
+            function::{FormalParameters, FunctionStatementList},
+        },
     },
     Context,
 };
@@ -190,6 +196,36 @@ impl<R> Parser<R> {
 
         Ok(statement_list)
     }
+
+    /// Parse the full input as an [ECMAScript `FunctionBody`][spec] into the boa AST representation.
+    ///
+    /// [spec]: https://tc39.es/ecma262/#prod-FunctionBody
+    pub(crate) fn parse_function_body(
+        &mut self,
+        interner: &mut Interner,
+        allow_yield: bool,
+        allow_await: bool,
+    ) -> Result<StatementList, ParseError>
+    where
+        R: Read,
+    {
+        FunctionStatementList::new(allow_yield, allow_await).parse(&mut self.cursor, interner)
+    }
+
+    /// Parse the full input as an [ECMAScript `FormalParameterList`][spec] into the boa AST representation.
+    ///
+    /// [spec]: https://tc39.es/ecma262/#prod-FormalParameterList
+    pub(crate) fn parse_formal_parameters(
+        &mut self,
+        interner: &mut Interner,
+        allow_yield: bool,
+        allow_await: bool,
+    ) -> Result<FormalParameterList, ParseError>
+    where
+        R: Read,
+    {
+        FormalParameters::new(allow_yield, allow_await).parse(&mut self.cursor, interner)
+    }
 }
 
 /// Parses a full script.

test_ignore.txt

@@ -8,8 +8,9 @@ feature:SharedArrayBuffer
 feature:resizable-arraybuffer
 feature:Temporal
 feature:tail-call-optimization
-//feature:async-iteration
-//feature:class
+
+// Non-standard
+feature:caller
 
 // These generate a stack overflow
 tco-call