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feat: Support $$ in macros.

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The implementation mirrors what `rustc` currently does [1]. Part of #11952.

[1]: 0595ea1d12/compiler/rustc_expand/src/mbe/quoted.rs (L230-L241)
This commit is contained in:
Tim Neumann 2022-06-02 21:36:11 +02:00
parent e25cbf8584
commit 40bfb29e50
3 changed files with 82 additions and 0 deletions
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68
crates/hir-def/src/macro_expansion_tests/mbe.rs
View File

@ -1544,3 +1544,71 @@ struct Foo;
"##]],
)
}
#[test]
fn test_dollar_dollar() {
check(
r#"
macro_rules! register_struct { ($Struct:ident) => {
macro_rules! register_methods { ($$($method:ident),*) => {
macro_rules! implement_methods { ($$$$($$val:expr),*) => {
struct $Struct;
impl $Struct { $$(fn $method() -> &'static [u32] { &[$$$$($$$$val),*] })*}
}}
}}
}}
register_struct!(Foo);
register_methods!(alpha, beta);
implement_methods!(1, 2, 3);
"#,
expect![[r#"
macro_rules! register_struct { ($Struct:ident) => {
macro_rules! register_methods { ($$($method:ident),*) => {
macro_rules! implement_methods { ($$$$($$val:expr),*) => {
struct $Struct;
impl $Struct { $$(fn $method() -> &'static [u32] { &[$$$$($$$$val),*] })*}
}}
}}
}}
macro_rules !register_methods {
($($method: ident), *) = > {
macro_rules!implement_methods {
($$($val: expr), *) = > {
struct Foo;
impl Foo {
$(fn $method()-> & 'static[u32] {
&[$$($$val), *]
}
)*
}
}
}
}
}
macro_rules !implement_methods {
($($val: expr), *) = > {
struct Foo;
impl Foo {
fn alpha()-> & 'static[u32] {
&[$($val), *]
}
fn beta()-> & 'static[u32] {
&[$($val), *]
}
}
}
}
struct Foo;
impl Foo {
fn alpha() -> & 'static[u32] {
&[1, 2, 3]
}
fn beta() -> & 'static[u32] {
&[1, 2, 3]
}
}
"#]],
)
}

6
crates/hir-def/src/macro_expansion_tests/mbe/meta_syntax.rs
View File

@ -56,6 +56,9 @@ macro_rules! f2 { ($i:) => ($i) }
f2!();
macro_rules! f3 { ($i:_) => () }
f3!();
macro_rules! m1 { ($$i) => () }
m1!();
"#,
expect![[r#"
macro_rules! i1 { invalid }
@ -74,6 +77,9 @@ macro_rules! f2 { ($i:) => ($i) }
/* error: invalid macro definition: missing fragment specifier */
macro_rules! f3 { ($i:_) => () }
/* error: invalid macro definition: missing fragment specifier */
macro_rules! m1 { ($$i) => () }
/* error: invalid macro definition: `$$` is not allowed on the pattern side */
"#]],
)
}

8
crates/mbe/src/parser.rs
View File

@ -135,6 +135,14 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul
let id = lit.id;
Op::Var { name, kind, id }
}
tt::Leaf::Punct(punct @ tt::Punct { char: '$', .. }) => match mode {
Mode::Pattern => {
return Err(ParseError::unexpected(
"`$$` is not allowed on the pattern side",
))
}
Mode::Template => Op::Leaf(tt::Leaf::Punct(*punct)),
},
tt::Leaf::Punct(_) | tt::Leaf::Literal(_) => {
return Err(ParseError::expected("expected ident"))
}