1 files changed, 649 insertions, 0 deletions

diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
new file mode 100644
index 000000000..86918b626
--- /dev/null
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -0,0 +1,649 @@
+//! Builtin macro
+use crate::{
+    db::AstDatabase, name, quote, AstId, CrateId, EagerMacroId, LazyMacroId, MacroCallId,
+    MacroDefId, MacroDefKind, TextSize,
+};
+
+use base_db::FileId;
+use either::Either;
+use mbe::parse_to_token_tree;
+use parser::FragmentKind;
+use syntax::ast::{self, AstToken, HasStringValue};
+
+macro_rules! register_builtin {
+    ( LAZY: $(($name:ident, $kind: ident) => $expand:ident),* , EAGER: $(($e_name:ident, $e_kind: ident) => $e_expand:ident),*  ) => {
+        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+        pub enum BuiltinFnLikeExpander {
+            $($kind),*
+        }
+
+        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+        pub enum EagerExpander {
+            $($e_kind),*
+        }
+
+        impl BuiltinFnLikeExpander {
+            pub fn expand(
+                &self,
+                db: &dyn AstDatabase,
+                id: LazyMacroId,
+                tt: &tt::Subtree,
+            ) -> Result<tt::Subtree, mbe::ExpandError> {
+                let expander = match *self {
+                    $( BuiltinFnLikeExpander::$kind => $expand, )*
+                };
+                expander(db, id, tt)
+            }
+        }
+
+        impl EagerExpander {
+            pub fn expand(
+                &self,
+                db: &dyn AstDatabase,
+                arg_id: EagerMacroId,
+                tt: &tt::Subtree,
+            ) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+                let expander = match *self {
+                    $( EagerExpander::$e_kind => $e_expand, )*
+                };
+                expander(db,arg_id,tt)
+            }
+        }
+
+        fn find_by_name(ident: &name::Name) -> Option<Either<BuiltinFnLikeExpander, EagerExpander>> {
+            match ident {
+                $( id if id == &name::name![$name] => Some(Either::Left(BuiltinFnLikeExpander::$kind)), )*
+                $( id if id == &name::name![$e_name] => Some(Either::Right(EagerExpander::$e_kind)), )*
+                _ => return None,
+            }
+        }
+    };
+}
+
+pub fn find_builtin_macro(
+    ident: &name::Name,
+    krate: CrateId,
+    ast_id: AstId<ast::MacroCall>,
+) -> Option<MacroDefId> {
+    let kind = find_by_name(ident)?;
+
+    match kind {
+        Either::Left(kind) => Some(MacroDefId {
+            krate: Some(krate),
+            ast_id: Some(ast_id),
+            kind: MacroDefKind::BuiltIn(kind),
+            local_inner: false,
+        }),
+        Either::Right(kind) => Some(MacroDefId {
+            krate: Some(krate),
+            ast_id: Some(ast_id),
+            kind: MacroDefKind::BuiltInEager(kind),
+            local_inner: false,
+        }),
+    }
+}
+
+register_builtin! {
+    LAZY:
+    (column, Column) => column_expand,
+    (compile_error, CompileError) => compile_error_expand,
+    (file, File) => file_expand,
+    (line, Line) => line_expand,
+    (assert, Assert) => assert_expand,
+    (stringify, Stringify) => stringify_expand,
+    (format_args, FormatArgs) => format_args_expand,
+    // format_args_nl only differs in that it adds a newline in the end,
+    // so we use the same stub expansion for now
+    (format_args_nl, FormatArgsNl) => format_args_expand,
+
+    EAGER:
+    (concat, Concat) => concat_expand,
+    (include, Include) => include_expand,
+    (include_bytes, IncludeBytes) => include_bytes_expand,
+    (include_str, IncludeStr) => include_str_expand,
+    (env, Env) => env_expand,
+    (option_env, OptionEnv) => option_env_expand
+}
+
+fn line_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // dummy implementation for type-checking purposes
+    let line_num = 0;
+    let expanded = quote! {
+        #line_num
+    };
+
+    Ok(expanded)
+}
+
+fn stringify_expand(
+    db: &dyn AstDatabase,
+    id: LazyMacroId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    let loc = db.lookup_intern_macro(id);
+
+    let macro_content = {
+        let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+        let macro_args = arg;
+        let text = macro_args.text();
+        let without_parens = TextSize::of('(')..text.len() - TextSize::of(')');
+        text.slice(without_parens).to_string()
+    };
+
+    let expanded = quote! {
+        #macro_content
+    };
+
+    Ok(expanded)
+}
+
+fn column_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // dummy implementation for type-checking purposes
+    let col_num = 0;
+    let expanded = quote! {
+        #col_num
+    };
+
+    Ok(expanded)
+}
+
+fn assert_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // A hacky implementation for goto def and hover
+    // We expand `assert!(cond, arg1, arg2)` to
+    // ```
+    // {(cond, &(arg1), &(arg2));}
+    // ```,
+    // which is wrong but useful.
+
+    let mut args = Vec::new();
+    let mut current = Vec::new();
+    for tt in tt.token_trees.iter().cloned() {
+        match tt {
+            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                args.push(current);
+                current = Vec::new();
+            }
+            _ => {
+                current.push(tt);
+            }
+        }
+    }
+    if !current.is_empty() {
+        args.push(current);
+    }
+
+    let arg_tts = args.into_iter().flat_map(|arg| {
+        quote! { &(##arg), }
+    }.token_trees).collect::<Vec<_>>();
+
+    let expanded = quote! {
+        { { (##arg_tts); } }
+    };
+    Ok(expanded)
+}
+
+fn file_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // FIXME: RA purposefully lacks knowledge of absolute file names
+    // so just return "".
+    let file_name = "";
+
+    let expanded = quote! {
+        #file_name
+    };
+
+    Ok(expanded)
+}
+
+fn compile_error_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    if tt.count() == 1 {
+        if let tt::TokenTree::Leaf(tt::Leaf::Literal(it)) = &tt.token_trees[0] {
+            let s = it.text.as_str();
+            if s.contains('"') {
+                return Ok(quote! { loop { #it }});
+            }
+        };
+    }
+
+    Err(mbe::ExpandError::BindingError("Must be a string".into()))
+}
+
+fn format_args_expand(
+    _db: &dyn AstDatabase,
+    _id: LazyMacroId,
+    tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // We expand `format_args!("", a1, a2)` to
+    // ```
+    // std::fmt::Arguments::new_v1(&[], &[
+    //   std::fmt::ArgumentV1::new(&arg1,std::fmt::Display::fmt),
+    //   std::fmt::ArgumentV1::new(&arg2,std::fmt::Display::fmt),
+    // ])
+    // ```,
+    // which is still not really correct, but close enough for now
+    let mut args = Vec::new();
+    let mut current = Vec::new();
+    for tt in tt.token_trees.iter().cloned() {
+        match tt {
+            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                args.push(current);
+                current = Vec::new();
+            }
+            _ => {
+                current.push(tt);
+            }
+        }
+    }
+    if !current.is_empty() {
+        args.push(current);
+    }
+    if args.is_empty() {
+        return Err(mbe::ExpandError::NoMatchingRule);
+    }
+    let _format_string = args.remove(0);
+    let arg_tts = args.into_iter().flat_map(|arg| {
+        quote! { std::fmt::ArgumentV1::new(&(##arg), std::fmt::Display::fmt), }
+    }.token_trees).collect::<Vec<_>>();
+    let expanded = quote! {
+        std::fmt::Arguments::new_v1(&[], &[##arg_tts])
+    };
+    Ok(expanded)
+}
+
+fn unquote_str(lit: &tt::Literal) -> Option<String> {
+    let lit = ast::make::tokens::literal(&lit.to_string());
+    let token = ast::String::cast(lit)?;
+    token.value().map(|it| it.into_owned())
+}
+
+fn concat_expand(
+    _db: &dyn AstDatabase,
+    _arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let mut text = String::new();
+    for (i, t) in tt.token_trees.iter().enumerate() {
+        match t {
+            tt::TokenTree::Leaf(tt::Leaf::Literal(it)) if i % 2 == 0 => {
+                text += &unquote_str(&it).ok_or_else(|| mbe::ExpandError::ConversionError)?;
+            }
+            tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) if i % 2 == 1 && punct.char == ',' => (),
+            _ => return Err(mbe::ExpandError::UnexpectedToken),
+        }
+    }
+
+    Ok((quote!(#text), FragmentKind::Expr))
+}
+
+fn relative_file(
+    db: &dyn AstDatabase,
+    call_id: MacroCallId,
+    path: &str,
+    allow_recursion: bool,
+) -> Option<FileId> {
+    let call_site = call_id.as_file().original_file(db);
+    let res = db.resolve_path(call_site, path)?;
+    // Prevent include itself
+    if res == call_site && !allow_recursion {
+        None
+    } else {
+        Some(res)
+    }
+}
+
+fn parse_string(tt: &tt::Subtree) -> Result<String, mbe::ExpandError> {
+    tt.token_trees
+        .get(0)
+        .and_then(|tt| match tt {
+            tt::TokenTree::Leaf(tt::Leaf::Literal(it)) => unquote_str(&it),
+            _ => None,
+        })
+        .ok_or_else(|| mbe::ExpandError::ConversionError)
+}
+
+fn include_expand(
+    db: &dyn AstDatabase,
+    arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let path = parse_string(tt)?;
+    let file_id = relative_file(db, arg_id.into(), &path, false)
+        .ok_or_else(|| mbe::ExpandError::ConversionError)?;
+
+    // FIXME:
+    // Handle include as expression
+    let res = parse_to_token_tree(&db.file_text(file_id))
+        .ok_or_else(|| mbe::ExpandError::ConversionError)?
+        .0;
+
+    Ok((res, FragmentKind::Items))
+}
+
+fn include_bytes_expand(
+    _db: &dyn AstDatabase,
+    _arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let _path = parse_string(tt)?;
+
+    // FIXME: actually read the file here if the user asked for macro expansion
+    let res = tt::Subtree {
+        delimiter: None,
+        token_trees: vec![tt::TokenTree::Leaf(tt::Leaf::Literal(tt::Literal {
+            text: r#"b"""#.into(),
+            id: tt::TokenId::unspecified(),
+        }))],
+    };
+    Ok((res, FragmentKind::Expr))
+}
+
+fn include_str_expand(
+    db: &dyn AstDatabase,
+    arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let path = parse_string(tt)?;
+
+    // FIXME: we're not able to read excluded files (which is most of them because
+    // it's unusual to `include_str!` a Rust file), but we can return an empty string.
+    // Ideally, we'd be able to offer a precise expansion if the user asks for macro
+    // expansion.
+    let file_id = match relative_file(db, arg_id.into(), &path, true) {
+        Some(file_id) => file_id,
+        None => {
+            return Ok((quote!(""), FragmentKind::Expr));
+        }
+    };
+
+    let text = db.file_text(file_id);
+    let text = &*text;
+
+    Ok((quote!(#text), FragmentKind::Expr))
+}
+
+fn get_env_inner(db: &dyn AstDatabase, arg_id: EagerMacroId, key: &str) -> Option<String> {
+    let krate = db.lookup_intern_eager_expansion(arg_id).krate;
+    db.crate_graph()[krate].env.get(key)
+}
+
+fn env_expand(
+    db: &dyn AstDatabase,
+    arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let key = parse_string(tt)?;
+
+    // FIXME:
+    // If the environment variable is not defined int rustc, then a compilation error will be emitted.
+    // We might do the same if we fully support all other stuffs.
+    // But for now on, we should return some dummy string for better type infer purpose.
+    // However, we cannot use an empty string here, because for
+    // `include!(concat!(env!("OUT_DIR"), "/foo.rs"))` will become
+    // `include!("foo.rs"), which might go to infinite loop
+    let s = get_env_inner(db, arg_id, &key).unwrap_or_else(|| "__RA_UNIMPLEMENTED__".to_string());
+    let expanded = quote! { #s };
+
+    Ok((expanded, FragmentKind::Expr))
+}
+
+fn option_env_expand(
+    db: &dyn AstDatabase,
+    arg_id: EagerMacroId,
+    tt: &tt::Subtree,
+) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+    let key = parse_string(tt)?;
+    let expanded = match get_env_inner(db, arg_id, &key) {
+        None => quote! { std::option::Option::None::<&str> },
+        Some(s) => quote! { std::option::Some(#s) },
+    };
+
+    Ok((expanded, FragmentKind::Expr))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{
+        name::AsName, test_db::TestDB, AstNode, EagerCallLoc, MacroCallId, MacroCallKind,
+        MacroCallLoc,
+    };
+    use base_db::{fixture::WithFixture, SourceDatabase};
+    use std::sync::Arc;
+    use syntax::ast::NameOwner;
+
+    fn expand_builtin_macro(ra_fixture: &str) -> String {
+        let (db, file_id) = TestDB::with_single_file(&ra_fixture);
+        let parsed = db.parse(file_id);
+        let macro_calls: Vec<_> =
+            parsed.syntax_node().descendants().filter_map(ast::MacroCall::cast).collect();
+
+        let ast_id_map = db.ast_id_map(file_id.into());
+
+        let expander = find_by_name(&macro_calls[0].name().unwrap().as_name()).unwrap();
+
+        let krate = CrateId(0);
+        let file_id = match expander {
+            Either::Left(expander) => {
+                // the first one should be a macro_rules
+                let def = MacroDefId {
+                    krate: Some(CrateId(0)),
+                    ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0]))),
+                    kind: MacroDefKind::BuiltIn(expander),
+                    local_inner: false,
+                };
+
+                let loc = MacroCallLoc {
+                    def,
+                    krate,
+                    kind: MacroCallKind::FnLike(AstId::new(
+                        file_id.into(),
+                        ast_id_map.ast_id(&macro_calls[1]),
+                    )),
+                };
+
+                let id: MacroCallId = db.intern_macro(loc).into();
+                id.as_file()
+            }
+            Either::Right(expander) => {
+                // the first one should be a macro_rules
+                let def = MacroDefId {
+                    krate: Some(krate),
+                    ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0]))),
+                    kind: MacroDefKind::BuiltInEager(expander),
+                    local_inner: false,
+                };
+
+                let args = macro_calls[1].token_tree().unwrap();
+                let parsed_args = mbe::ast_to_token_tree(&args).unwrap().0;
+
+                let arg_id = db.intern_eager_expansion({
+                    EagerCallLoc {
+                        def,
+                        fragment: FragmentKind::Expr,
+                        subtree: Arc::new(parsed_args.clone()),
+                        krate,
+                        file_id: file_id.into(),
+                    }
+                });
+
+                let (subtree, fragment) = expander.expand(&db, arg_id, &parsed_args).unwrap();
+                let eager = EagerCallLoc {
+                    def,
+                    fragment,
+                    subtree: Arc::new(subtree),
+                    krate,
+                    file_id: file_id.into(),
+                };
+
+                let id: MacroCallId = db.intern_eager_expansion(eager).into();
+                id.as_file()
+            }
+        };
+
+        db.parse_or_expand(file_id).unwrap().to_string()
+    }
+
+    #[test]
+    fn test_column_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! column {() => {}}
+            column!()
+            "#,
+        );
+
+        assert_eq!(expanded, "0");
+    }
+
+    #[test]
+    fn test_line_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! line {() => {}}
+            line!()
+            "#,
+        );
+
+        assert_eq!(expanded, "0");
+    }
+
+    #[test]
+    fn test_stringify_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! stringify {() => {}}
+            stringify!(a b c)
+            "#,
+        );
+
+        assert_eq!(expanded, "\"a b c\"");
+    }
+
+    #[test]
+    fn test_env_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! env {() => {}}
+            env!("TEST_ENV_VAR")
+            "#,
+        );
+
+        assert_eq!(expanded, "\"__RA_UNIMPLEMENTED__\"");
+    }
+
+    #[test]
+    fn test_option_env_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! option_env {() => {}}
+            option_env!("TEST_ENV_VAR")
+            "#,
+        );
+
+        assert_eq!(expanded, "std::option::Option::None:: < &str>");
+    }
+
+    #[test]
+    fn test_file_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! file {() => {}}
+            file!()
+            "#,
+        );
+
+        assert_eq!(expanded, "\"\"");
+    }
+
+    #[test]
+    fn test_assert_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! assert {
+                ($cond:expr) => ({ /* compiler built-in */ });
+                ($cond:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+            }
+            assert!(true, "{} {:?}", arg1(a, b, c), arg2);
+            "#,
+        );
+
+        assert_eq!(expanded, "{{(&(true), &(\"{} {:?}\"), &(arg1(a,b,c)), &(arg2),);}}");
+    }
+
+    #[test]
+    fn test_compile_error_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! compile_error {
+                ($msg:expr) => ({ /* compiler built-in */ });
+                ($msg:expr,) => ({ /* compiler built-in */ })
+            }
+            compile_error!("error!");
+            "#,
+        );
+
+        assert_eq!(expanded, r#"loop{"error!"}"#);
+    }
+
+    #[test]
+    fn test_format_args_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! format_args {
+                ($fmt:expr) => ({ /* compiler built-in */ });
+                ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+            }
+            format_args!("{} {:?}", arg1(a, b, c), arg2);
+            "#,
+        );
+
+        assert_eq!(
+            expanded,
+            r#"std::fmt::Arguments::new_v1(&[], &[std::fmt::ArgumentV1::new(&(arg1(a,b,c)),std::fmt::Display::fmt),std::fmt::ArgumentV1::new(&(arg2),std::fmt::Display::fmt),])"#
+        );
+    }
+
+    #[test]
+    fn test_include_bytes_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! include_bytes {
+                ($file:expr) => {{ /* compiler built-in */ }};
+                ($file:expr,) => {{ /* compiler built-in */ }};
+            }
+            include_bytes("foo");
+            "#,
+        );
+
+        assert_eq!(expanded, r#"b"""#);
+    }
+}