feat: argument defaults can be any expr valid in const scope

`None` for example

Refs: #433

Author: alekitto

crates/macros/src/function.rs

@@ -4,8 +4,7 @@ use darling::{FromAttributes, ToTokens};
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{format_ident, quote};
 use syn::spanned::Spanned as _;
-use syn::PatType;
-use syn::{FnArg, GenericArgument, ItemFn, Lit, PathArguments, Type, TypePath};
+use syn::{Expr, FnArg, GenericArgument, ItemFn, PatType, PathArguments, Type, TypePath};
 
 use crate::helpers::get_docs;
 use crate::parsing::{PhpRename, Visibility};
@@ -28,7 +27,7 @@ pub fn wrap(input: &syn::Path) -> Result<TokenStream> {
 struct PhpFunctionAttribute {
     #[darling(flatten)]
     rename: PhpRename,
-    defaults: HashMap<Ident, Lit>,
+    defaults: HashMap<Ident, Expr>,
     optional: Option<Ident>,
     vis: Option<Visibility>,
     attrs: Vec<syn::Attribute>,
@@ -381,7 +380,7 @@ pub struct TypedArg<'a> {
     pub name: &'a Ident,
     pub ty: Type,
     pub nullable: bool,
-    pub default: Option<Lit>,
+    pub default: Option<Expr>,
     pub as_ref: bool,
     pub variadic: bool,
 }
@@ -395,7 +394,7 @@ pub struct Args<'a> {
 impl<'a> Args<'a> {
     pub fn parse_from_fnargs(
         args: impl Iterator<Item = &'a FnArg>,
-        mut defaults: HashMap<Ident, Lit>,
+        mut defaults: HashMap<Ident, Expr>,
     ) -> Result<Self> {
         let mut result = Self {
             receiver: None,

crates/macros/src/impl_.rs

@@ -3,7 +3,7 @@ use darling::FromAttributes;
 use proc_macro2::TokenStream;
 use quote::quote;
 use std::collections::{HashMap, HashSet};
-use syn::{Ident, ItemImpl, Lit};
+use syn::{Expr, Ident, ItemImpl};
 
 use crate::constant::PhpConstAttribute;
 use crate::function::{Args, CallType, Function, MethodReceiver};
@@ -68,7 +68,7 @@ struct MethodArgs {
     /// The first optional argument of the function signature.
     optional: Option<Ident>,
     /// Default values for optional arguments.
-    defaults: HashMap<Ident, Lit>,
+    defaults: HashMap<Ident, Expr>,
     /// Visibility of the method (public, protected, private).
     vis: Visibility,
     /// Method type.
@@ -80,7 +80,7 @@ struct MethodArgs {
 pub struct PhpFunctionImplAttribute {
     #[darling(flatten)]
     rename: PhpRename,
-    defaults: HashMap<Ident, Lit>,
+    defaults: HashMap<Ident, Expr>,
     optional: Option<Ident>,
     vis: Option<Visibility>,
     attrs: Vec<syn::Attribute>,

tests/src/integration/defaults/defaults.php

@@ -0,0 +1,6 @@
+<?php
+
+assert(test_defaults_integer() === 42);
+assert(test_defaults_integer(12) === 12);
+assert(test_defaults_nullable_string() === null);
+assert(test_defaults_nullable_string('test') === 'test');

tests/src/integration/defaults/mod.rs

@@ -0,0 +1,27 @@
+use ext_php_rs::prelude::*;
+
+#[php_function]
+#[php(defaults(a = 42))]
+pub fn test_defaults_integer(a: i32) -> i32 {
+    a
+}
+
+#[php_function]
+#[php(defaults(a = None))]
+pub fn test_defaults_nullable_string(a: Option<String>) -> Option<String> {
+    a
+}
+
+pub fn build_module(builder: ModuleBuilder) -> ModuleBuilder {
+    builder
+        .function(wrap_function!(test_defaults_integer))
+        .function(wrap_function!(test_defaults_nullable_string))
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn defaults_works() {
+        assert!(crate::integration::test::run_php("defaults/defaults.php"));
+    }
+}

tests/src/integration/mod.rs

@@ -4,6 +4,7 @@ pub mod bool;
 pub mod callable;
 pub mod class;
 pub mod closure;
+pub mod defaults;
 pub mod globals;
 pub mod iterator;
 pub mod magic_method;

tests/src/lib.rs

@@ -17,6 +17,7 @@ pub fn build_module(module: ModuleBuilder) -> ModuleBuilder {
     module = integration::callable::build_module(module);
     module = integration::class::build_module(module);
     module = integration::closure::build_module(module);
+    module = integration::defaults::build_module(module);
     module = integration::globals::build_module(module);
     module = integration::iterator::build_module(module);
     module = integration::magic_method::build_module(module);