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Merge #8732

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8732: internal: refactor expansion queries r=matklad a=matklad

bors r+
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Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>
This commit is contained in:
bors[bot] 2021-05-04 19:42:30 +00:00 committed by GitHub
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4 changed files with 259 additions and 221 deletions
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410
crates/hir_expand/src/db.rs
View file

@ -28,9 +28,9 @@ const TOKEN_LIMIT: usize = 524288;
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum TokenExpander {
/// Old-style `macro_rules`.
MacroRules(mbe::MacroRules),
MacroRules { mac: mbe::MacroRules, def_site_token_map: mbe::TokenMap },
/// AKA macros 2.0.
MacroDef(mbe::MacroDef),
MacroDef { mac: mbe::MacroDef, def_site_token_map: mbe::TokenMap },
/// Stuff like `line!` and `file!`.
Builtin(BuiltinFnLikeExpander),
/// `derive(Copy)` and such.
@ -47,8 +47,8 @@ impl TokenExpander {
tt: &tt::Subtree,
) -> mbe::ExpandResult<tt::Subtree> {
match self {
TokenExpander::MacroRules(it) => it.expand(tt),
TokenExpander::MacroDef(it) => it.expand(tt),
TokenExpander::MacroRules { mac, .. } => mac.expand(tt),
TokenExpander::MacroDef { mac, .. } => mac.expand(tt),
TokenExpander::Builtin(it) => it.expand(db, id, tt),
// FIXME switch these to ExpandResult as well
TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
@ -63,21 +63,21 @@ impl TokenExpander {
pub(crate) fn map_id_down(&self, id: tt::TokenId) -> tt::TokenId {
match self {
TokenExpander::MacroRules(it) => it.map_id_down(id),
TokenExpander::MacroDef(it) => it.map_id_down(id),
TokenExpander::Builtin(..) => id,
TokenExpander::BuiltinDerive(..) => id,
TokenExpander::ProcMacro(..) => id,
TokenExpander::MacroRules { mac, .. } => mac.map_id_down(id),
TokenExpander::MacroDef { mac, .. } => mac.map_id_down(id),
TokenExpander::Builtin(..)
| TokenExpander::BuiltinDerive(..)
| TokenExpander::ProcMacro(..) => id,
}
}
pub(crate) fn map_id_up(&self, id: tt::TokenId) -> (tt::TokenId, mbe::Origin) {
match self {
TokenExpander::MacroRules(it) => it.map_id_up(id),
TokenExpander::MacroDef(it) => it.map_id_up(id),
TokenExpander::Builtin(..) => (id, mbe::Origin::Call),
TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Call),
TokenExpander::ProcMacro(..) => (id, mbe::Origin::Call),
TokenExpander::MacroRules { mac, .. } => mac.map_id_up(id),
TokenExpander::MacroDef { mac, .. } => mac.map_id_up(id),
TokenExpander::Builtin(..)
| TokenExpander::BuiltinDerive(..)
| TokenExpander::ProcMacro(..) => (id, mbe::Origin::Call),
}
}
}
@ -87,28 +87,48 @@ impl TokenExpander {
pub trait AstDatabase: SourceDatabase {
fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;
/// Main public API -- parsis a hir file, not caring whether it's a real
/// file or a macro expansion.
#[salsa::transparent]
fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode>;
#[salsa::interned]
fn intern_macro(&self, macro_call: MacroCallLoc) -> LazyMacroId;
fn macro_arg_text(&self, id: MacroCallId) -> Option<GreenNode>;
#[salsa::transparent]
fn macro_arg(&self, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>>;
fn macro_def(&self, id: MacroDefId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>>;
/// Implementation for the macro case.
fn parse_macro_expansion(
&self,
macro_file: MacroFile,
) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>>;
fn macro_expand(&self, macro_call: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>>;
/// Firewall query that returns the error from the `macro_expand` query.
fn macro_expand_error(&self, macro_call: MacroCallId) -> Option<ExpandError>;
/// Macro ids. That's probably the tricksiest bit in rust-analyzer, and the
/// reason why we use salsa at all.
///
/// We encode macro definitions into ids of macro calls, this what allows us
/// to be incremental.
#[salsa::interned]
fn intern_macro(&self, macro_call: MacroCallLoc) -> LazyMacroId;
/// Certain built-in macros are eager (`format!(concat!("file: ", file!(), "{}"")), 92`).
/// For them, we actually want to encode the whole token tree as an argument.
#[salsa::interned]
fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
/// Lowers syntactic macro call to a token tree representation.
#[salsa::transparent]
fn macro_arg(&self, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>>;
/// Extracts syntax node, corresponding to a macro call. That's a firewall
/// query, only typing in the macro call itself changes the returned
/// subtree.
fn macro_arg_text(&self, id: MacroCallId) -> Option<GreenNode>;
/// Gets the expander for this macro. This compiles declarative macros, and
/// just fetches procedural ones.
fn macro_def(&self, id: MacroDefId) -> Option<Arc<TokenExpander>>;
/// Expand macro call to a token tree. This query is LRUed (we keep 128 or so results in memory)
fn macro_expand(&self, macro_call: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>>;
/// Special case of the previous query for procedural macros. We can't LRU
/// proc macros, since they are not deterministic in general, and
/// non-determinism breaks salsa in a very, very, very bad way. @edwin0cheng
/// heroically debugged this once!
fn expand_proc_macro(&self, call: MacroCallId) -> Result<tt::Subtree, mbe::ExpandError>;
/// Firewall query that returns the error from the `macro_expand` query.
fn macro_expand_error(&self, macro_call: MacroCallId) -> Option<ExpandError>;
fn hygiene_frame(&self, file_id: HirFileId) -> Arc<HygieneFrame>;
}
@ -123,182 +143,39 @@ pub fn expand_hypothetical(
hypothetical_args: &ast::TokenTree,
token_to_map: SyntaxToken,
) -> Option<(SyntaxNode, SyntaxToken)> {
let macro_file = MacroFile { macro_call_id: actual_macro_call };
let (tt, tmap_1) = mbe::syntax_node_to_token_tree(hypothetical_args.syntax());
let range =
token_to_map.text_range().checked_sub(hypothetical_args.syntax().text_range().start())?;
let token_id = tmap_1.token_by_range(range)?;
let macro_def = expander(db, actual_macro_call)?;
let lazy_id = match actual_macro_call {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_) => return None,
};
let macro_def = {
let loc = db.lookup_intern_macro(lazy_id);
db.macro_def(loc.def)?
};
let hypothetical_expansion = macro_def.expand(db, lazy_id, &tt);
let fragment_kind = to_fragment_kind(db, actual_macro_call);
let (node, tmap_2) =
parse_macro_with_arg(db, macro_file, Some(std::sync::Arc::new((tt, tmap_1)))).value?;
let token_id = macro_def.0.map_id_down(token_id);
mbe::token_tree_to_syntax_node(&hypothetical_expansion.value, fragment_kind).ok()?;
let token_id = macro_def.map_id_down(token_id);
let range = tmap_2.range_by_token(token_id)?.by_kind(token_to_map.kind())?;
let token = node.syntax_node().covering_element(range).into_token()?;
Some((node.syntax_node(), token))
}
fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
let map =
db.parse_or_expand(file_id).map_or_else(AstIdMap::default, |it| AstIdMap::from_source(&it));
let map = db.parse_or_expand(file_id).map(|it| AstIdMap::from_source(&it)).unwrap_or_default();
Arc::new(map)
}
fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
match id.kind {
MacroDefKind::Declarative(ast_id) => match ast_id.to_node(db) {
ast::Macro::MacroRules(macro_rules) => {
let arg = macro_rules.token_tree()?;
let (tt, tmap) = mbe::ast_to_token_tree(&arg);
let rules = match mbe::MacroRules::parse(&tt) {
Ok(it) => it,
Err(err) => {
let name = macro_rules.name().map(|n| n.to_string()).unwrap_or_default();
log::warn!("fail on macro_def parse ({}): {:?} {:#?}", name, err, tt);
return None;
}
};
Some(Arc::new((TokenExpander::MacroRules(rules), tmap)))
}
ast::Macro::MacroDef(macro_def) => {
let arg = macro_def.body()?;
let (tt, tmap) = mbe::ast_to_token_tree(&arg);
let rules = match mbe::MacroDef::parse(&tt) {
Ok(it) => it,
Err(err) => {
let name = macro_def.name().map(|n| n.to_string()).unwrap_or_default();
log::warn!("fail on macro_def parse ({}): {:?} {:#?}", name, err, tt);
return None;
}
};
Some(Arc::new((TokenExpander::MacroDef(rules), tmap)))
}
},
MacroDefKind::BuiltIn(expander, _) => {
Some(Arc::new((TokenExpander::Builtin(expander), mbe::TokenMap::default())))
}
MacroDefKind::BuiltInDerive(expander, _) => {
Some(Arc::new((TokenExpander::BuiltinDerive(expander), mbe::TokenMap::default())))
}
MacroDefKind::BuiltInEager(..) => None,
MacroDefKind::ProcMacro(expander, ..) => {
Some(Arc::new((TokenExpander::ProcMacro(expander), mbe::TokenMap::default())))
}
}
}
fn macro_arg_text(db: &dyn AstDatabase, id: MacroCallId) -> Option<GreenNode> {
let id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_id) => {
// FIXME: support macro_arg for eager macro
return None;
}
};
let loc = db.lookup_intern_macro(id);
let arg = loc.kind.arg(db)?;
Some(arg.green())
}
fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
let arg = db.macro_arg_text(id)?;
let (tt, tmap) = mbe::syntax_node_to_token_tree(&SyntaxNode::new_root(arg));
Some(Arc::new((tt, tmap)))
}
fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>> {
macro_expand_with_arg(db, id, None)
}
fn macro_expand_error(db: &dyn AstDatabase, macro_call: MacroCallId) -> Option<ExpandError> {
db.macro_expand(macro_call).err
}
fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
let lazy_id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_id) => {
return None;
}
};
let loc = db.lookup_intern_macro(lazy_id);
let macro_rules = db.macro_def(loc.def)?;
Some(macro_rules)
}
fn macro_expand_with_arg(
db: &dyn AstDatabase,
id: MacroCallId,
arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
) -> ExpandResult<Option<Arc<tt::Subtree>>> {
let _p = profile::span("macro_expand");
let lazy_id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(id) => {
if arg.is_some() {
return ExpandResult::str_err(
"hypothetical macro expansion not implemented for eager macro".to_owned(),
);
} else {
return ExpandResult {
value: Some(db.lookup_intern_eager_expansion(id).subtree),
// FIXME: There could be errors here!
err: None,
};
}
}
};
let loc = db.lookup_intern_macro(lazy_id);
let macro_arg = match arg.or_else(|| db.macro_arg(id)) {
Some(it) => it,
None => return ExpandResult::str_err("Fail to args in to tt::TokenTree".into()),
};
let macro_rules = match db.macro_def(loc.def) {
Some(it) => it,
None => return ExpandResult::str_err("Fail to find macro definition".into()),
};
let ExpandResult { value: tt, err } = macro_rules.0.expand(db, lazy_id, &macro_arg.0);
// Set a hard limit for the expanded tt
let count = tt.count();
if count > TOKEN_LIMIT {
return ExpandResult::str_err(format!(
"macro invocation exceeds token limit: produced {} tokens, limit is {}",
count, TOKEN_LIMIT,
));
}
ExpandResult { value: Some(Arc::new(tt)), err }
}
fn expand_proc_macro(
db: &dyn AstDatabase,
id: MacroCallId,
) -> Result<tt::Subtree, mbe::ExpandError> {
let lazy_id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_) => unreachable!(),
};
let loc = db.lookup_intern_macro(lazy_id);
let macro_arg = match db.macro_arg(id) {
Some(it) => it,
None => {
return Err(
tt::ExpansionError::Unknown("No arguments for proc-macro".to_string()).into()
)
}
};
let expander = match loc.def.kind {
MacroDefKind::ProcMacro(expander, ..) => expander,
_ => unreachable!(),
};
expander.expand(db, loc.krate, &macro_arg.0)
}
fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Option<SyntaxNode> {
match file_id.0 {
HirFileIdRepr::FileId(file_id) => Some(db.parse(file_id).tree().syntax().clone()),
@ -312,28 +189,14 @@ fn parse_macro_expansion(
db: &dyn AstDatabase,
macro_file: MacroFile,
) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>> {
parse_macro_with_arg(db, macro_file, None)
}
fn parse_macro_with_arg(
db: &dyn AstDatabase,
macro_file: MacroFile,
arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>> {
let macro_call_id = macro_file.macro_call_id;
let result = if let Some(arg) = arg {
macro_expand_with_arg(db, macro_call_id, Some(arg))
} else {
db.macro_expand(macro_call_id)
};
let _p = profile::span("parse_macro_expansion");
let result = db.macro_expand(macro_file.macro_call_id);
if let Some(err) = &result.err {
// Note:
// The final goal we would like to make all parse_macro success,
// such that the following log will not call anyway.
match macro_call_id {
match macro_file.macro_call_id {
MacroCallId::LazyMacro(id) => {
let loc: MacroCallLoc = db.lookup_intern_macro(id);
let node = loc.kind.node(db);
@ -363,7 +226,7 @@ fn parse_macro_with_arg(
None => return ExpandResult { value: None, err: result.err },
};
let fragment_kind = to_fragment_kind(db, macro_call_id);
let fragment_kind = to_fragment_kind(db, macro_file.macro_call_id);
log::debug!("expanded = {}", tt.as_debug_string());
log::debug!("kind = {:?}", fragment_kind);
@ -404,6 +267,145 @@ fn parse_macro_with_arg(
}
}
fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
let arg = db.macro_arg_text(id)?;
let (tt, tmap) = mbe::syntax_node_to_token_tree(&SyntaxNode::new_root(arg));
Some(Arc::new((tt, tmap)))
}
fn macro_arg_text(db: &dyn AstDatabase, id: MacroCallId) -> Option<GreenNode> {
let id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_id) => {
// FIXME: support macro_arg for eager macro
return None;
}
};
let loc = db.lookup_intern_macro(id);
let arg = loc.kind.arg(db)?;
Some(arg.green())
}
fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<TokenExpander>> {
match id.kind {
MacroDefKind::Declarative(ast_id) => match ast_id.to_node(db) {
ast::Macro::MacroRules(macro_rules) => {
let arg = macro_rules.token_tree()?;
let (tt, def_site_token_map) = mbe::ast_to_token_tree(&arg);
let mac = match mbe::MacroRules::parse(&tt) {
Ok(it) => it,
Err(err) => {
let name = macro_rules.name().map(|n| n.to_string()).unwrap_or_default();
log::warn!("fail on macro_def parse ({}): {:?} {:#?}", name, err, tt);
return None;
}
};
Some(Arc::new(TokenExpander::MacroRules { mac, def_site_token_map }))
}
ast::Macro::MacroDef(macro_def) => {
let arg = macro_def.body()?;
let (tt, def_site_token_map) = mbe::ast_to_token_tree(&arg);
let mac = match mbe::MacroDef::parse(&tt) {
Ok(it) => it,
Err(err) => {
let name = macro_def.name().map(|n| n.to_string()).unwrap_or_default();
log::warn!("fail on macro_def parse ({}): {:?} {:#?}", name, err, tt);
return None;
}
};
Some(Arc::new(TokenExpander::MacroDef { mac, def_site_token_map }))
}
},
MacroDefKind::BuiltIn(expander, _) => Some(Arc::new(TokenExpander::Builtin(expander))),
MacroDefKind::BuiltInDerive(expander, _) => {
Some(Arc::new(TokenExpander::BuiltinDerive(expander)))
}
MacroDefKind::BuiltInEager(..) => None,
MacroDefKind::ProcMacro(expander, ..) => Some(Arc::new(TokenExpander::ProcMacro(expander))),
}
}
fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>> {
macro_expand_with_arg(db, id, None)
}
fn macro_expand_error(db: &dyn AstDatabase, macro_call: MacroCallId) -> Option<ExpandError> {
db.macro_expand(macro_call).err
}
fn macro_expand_with_arg(
db: &dyn AstDatabase,
id: MacroCallId,
arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
) -> ExpandResult<Option<Arc<tt::Subtree>>> {
let _p = profile::span("macro_expand");
let lazy_id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(id) => {
if arg.is_some() {
return ExpandResult::str_err(
"hypothetical macro expansion not implemented for eager macro".to_owned(),
);
} else {
return ExpandResult {
value: Some(db.lookup_intern_eager_expansion(id).subtree),
// FIXME: There could be errors here!
err: None,
};
}
}
};
let loc = db.lookup_intern_macro(lazy_id);
let macro_arg = match arg.or_else(|| db.macro_arg(id)) {
Some(it) => it,
None => return ExpandResult::str_err("Fail to args in to tt::TokenTree".into()),
};
let macro_rules = match db.macro_def(loc.def) {
Some(it) => it,
None => return ExpandResult::str_err("Fail to find macro definition".into()),
};
let ExpandResult { value: tt, err } = macro_rules.expand(db, lazy_id, &macro_arg.0);
// Set a hard limit for the expanded tt
let count = tt.count();
if count > TOKEN_LIMIT {
return ExpandResult::str_err(format!(
"macro invocation exceeds token limit: produced {} tokens, limit is {}",
count, TOKEN_LIMIT,
));
}
ExpandResult { value: Some(Arc::new(tt)), err }
}
fn expand_proc_macro(
db: &dyn AstDatabase,
id: MacroCallId,
) -> Result<tt::Subtree, mbe::ExpandError> {
let lazy_id = match id {
MacroCallId::LazyMacro(id) => id,
MacroCallId::EagerMacro(_) => unreachable!(),
};
let loc = db.lookup_intern_macro(lazy_id);
let macro_arg = match db.macro_arg(id) {
Some(it) => it,
None => {
return Err(
tt::ExpansionError::Unknown("No arguments for proc-macro".to_string()).into()
)
}
};
let expander = match loc.def.kind {
MacroDefKind::ProcMacro(expander, ..) => expander,
_ => unreachable!(),
};
expander.expand(db, loc.krate, &macro_arg.0)
}
fn is_self_replicating(from: &SyntaxNode, to: &SyntaxNode) -> bool {
if diff(from, to).is_empty() {
return true;

16
crates/hir_expand/src/hygiene.rs
View file

@ -5,6 +5,7 @@
use std::sync::Arc;
use base_db::CrateId;
use db::TokenExpander;
use either::Either;
use mbe::Origin;
use parser::SyntaxKind;
@ -115,7 +116,7 @@ struct HygieneInfo {
/// The `macro_rules!` arguments.
def_start: Option<InFile<TextSize>>,
macro_def: Arc<(db::TokenExpander, mbe::TokenMap)>,
macro_def: Arc<TokenExpander>,
macro_arg: Arc<(tt::Subtree, mbe::TokenMap)>,
exp_map: Arc<mbe::TokenMap>,
}
@ -124,13 +125,16 @@ impl HygieneInfo {
fn map_ident_up(&self, token: TextRange) -> Option<(InFile<TextRange>, Origin)> {
let token_id = self.exp_map.token_by_range(token)?;
let (token_id, origin) = self.macro_def.0.map_id_up(token_id);
let (token_id, origin) = self.macro_def.map_id_up(token_id);
let (token_map, tt) = match origin {
mbe::Origin::Call => (&self.macro_arg.1, self.arg_start),
mbe::Origin::Def => (
&self.macro_def.1,
*self.def_start.as_ref().expect("`Origin::Def` used with non-`macro_rules!` macro"),
),
mbe::Origin::Def => match (&*self.macro_def, self.def_start) {
(TokenExpander::MacroDef { def_site_token_map, .. }, Some(tt))
| (TokenExpander::MacroRules { def_site_token_map, .. }, Some(tt)) => {
(def_site_token_map, tt)
}
_ => panic!("`Origin::Def` used with non-`macro_rules!` macro"),
},
};
let range = token_map.range_by_token(token_id)?.by_kind(SyntaxKind::IDENT)?;

21
crates/hir_expand/src/lib.rs
View file

@ -351,7 +351,7 @@ pub struct ExpansionInfo {
/// The `macro_rules!` arguments.
def: Option<InFile<ast::TokenTree>>,
macro_def: Arc<(db::TokenExpander, mbe::TokenMap)>,
macro_def: Arc<db::TokenExpander>,
macro_arg: Arc<(tt::Subtree, mbe::TokenMap)>,
exp_map: Arc<mbe::TokenMap>,
}
@ -368,7 +368,7 @@ impl ExpansionInfo {
assert_eq!(token.file_id, self.arg.file_id);
let range = token.value.text_range().checked_sub(self.arg.value.text_range().start())?;
let token_id = self.macro_arg.1.token_by_range(range)?;
let token_id = self.macro_def.0.map_id_down(token_id);
let token_id = self.macro_def.map_id_down(token_id);
let range = self.exp_map.range_by_token(token_id)?.by_kind(token.value.kind())?;
@ -383,17 +383,16 @@ impl ExpansionInfo {
) -> Option<(InFile<SyntaxToken>, Origin)> {
let token_id = self.exp_map.token_by_range(token.value.text_range())?;
let (token_id, origin) = self.macro_def.0.map_id_up(token_id);
let (token_id, origin) = self.macro_def.map_id_up(token_id);
let (token_map, tt) = match origin {
mbe::Origin::Call => (&self.macro_arg.1, self.arg.clone()),
mbe::Origin::Def => (
&self.macro_def.1,
self.def
.as_ref()
.expect("`Origin::Def` used with non-`macro_rules!` macro")
.as_ref()
.map(|tt| tt.syntax().clone()),
),
mbe::Origin::Def => match (&*self.macro_def, self.def.as_ref()) {
(db::TokenExpander::MacroRules { def_site_token_map, .. }, Some(tt))
| (db::TokenExpander::MacroDef { def_site_token_map, .. }, Some(tt)) => {
(def_site_token_map, tt.as_ref().map(|tt| tt.syntax().clone()))
}
_ => panic!("`Origin::Def` used with non-`macro_rules!` macro"),
},
};
let range = token_map.range_by_token(token_id)?.by_kind(token.value.kind())?;

33
docs/dev/style.md
View file

@ -449,6 +449,39 @@ fn query_all(name: String, case_sensitive: bool) -> Vec<Item> { ... }
fn query_first(name: String, case_sensitive: bool) -> Option<Item> { ... }
```
## Prefer Separate Functions Over Parameters
If a function has a `bool` or an `Option` parameter, and it is always called with `true`, `false`, `Some` and `None` literals, split the function in two.
```rust
// GOOD
fn caller_a() {
foo()
}
fn caller_b() {
foo_with_bar(Bar::new())
}
fn foo() { ... }
fn foo_with_bar(bar: Bar) { ... }
// BAD
fn caller_a() {
foo(None)
}
fn caller_b() {
foo(Some(Bar::new()))
}
fn foo(bar: Option<Bar>) { ... }
```
**Rationale:** more often than not, such functions display "`false sharing`" -- they have additional `if` branching inside for two different cases.
Splitting the two different control flows into two functions simplifies each path, and remove cross-dependencies between the two paths.
If there's common code between `foo` and `foo_with_bar`, extract *that* into a common helper.
## Avoid Monomorphization
Avoid making a lot of code type parametric, *especially* on the boundaries between crates.