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Reapply the derive helper changes from master
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@petrochenkov
petrochenkov committed Oct 5, 2018
1 parent 8994c6d commit c29fb80
Showing 1 changed file with 38 additions and 37 deletions.
75 changes: 38 additions & 37 deletions src/librustc_resolve/macros.rs
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Expand Up @@ -554,35 +554,35 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
// (open, not controlled).
// 3. Standard library prelude (de-facto closed, controlled).
// (Macro NS)
// 1-2. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
// 1-3. Derive helpers (open, not controlled). All ambiguities with other names
// are currently reported as errors. They should be higher in priority than preludes
// and probably even names in modules according to the "general principles" above. They
// also should be subject to restricted shadowing because are effectively produced by
// derives (you need to resolve the derive first to add helpers into scope), but they
// should be available before the derive is expanded for compatibility.
// It's mess in general, so we are being conservative for now.
// 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
// priority than prelude macros, but create ambiguities with macros in modules.
// 1-2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
// 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
// (open, not controlled). Have higher priority than prelude macros, but create
// ambiguities with `macro_rules`.
// 3. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
// 3a. User-defined prelude from macro-use
// 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
// 4a. User-defined prelude from macro-use
// (open, the open part is from macro expansions, not controlled).
// 3b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
// 4b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
// 5. Language prelude: builtin macros (closed, controlled, except for legacy plugins).
// 6. Language prelude: builtin attributes (closed, controlled).
// 3-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
// 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
// but introduced by legacy plugins using `register_attribute`. Priority is somewhere
// in prelude, not sure where exactly (creates ambiguities with any other prelude names).
// N (unordered). Derive helpers (open, not controlled). All ambiguities with other names
// are currently reported as errors. They should be higher in priority than preludes
// and maybe even names in modules according to the "general principles" above. They
// also should be subject to restricted shadowing because are effectively produced by
// derives (you need to resolve the derive first to add helpers into scope), but they
// should be available before the derive is expanded for compatibility.
// It's mess in general, so we are being conservative for now.

enum WhereToResolve<'a> {
DeriveHelpers,
MacroRules(LegacyScope<'a>),
Module(Module<'a>),
MacroUsePrelude,
BuiltinMacros,
BuiltinAttrs,
DeriveHelpers,
LegacyPluginHelpers,
ExternPrelude,
ToolPrelude,
Expand Down Expand Up @@ -616,10 +616,30 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
let mut innermost_result: Option<(&NameBinding, Flags, /* conflicts with */ Flags)> = None;

// Go through all the scopes and try to resolve the name.
let mut where_to_resolve = WhereToResolve::MacroRules(parent_scope.legacy);
let mut where_to_resolve = WhereToResolve::DeriveHelpers;
let mut use_prelude = !parent_scope.module.no_implicit_prelude;
loop {
let result = match where_to_resolve {
WhereToResolve::DeriveHelpers => {
let mut result = Err(Determinacy::Determined);
for derive in &parent_scope.derives {
let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
if let Ok((_, ext)) = self.resolve_macro_to_def(derive, MacroKind::Derive,
&parent_scope, force) {
if let SyntaxExtension::ProcMacroDerive(_, helper_attrs, _) = &*ext {
if helper_attrs.contains(&ident.name) {
let binding =
(Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
ty::Visibility::Public, derive.span, Mark::root())
.to_name_binding(self.arenas);
result = Ok((binding, Flags::DERIVE_HELPERS, Flags::all()));
break;
}
}
}
}
result
}
WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
Ok((legacy_binding.binding, Flags::MACRO_RULES, Flags::MODULE)),
Expand Down Expand Up @@ -660,26 +680,6 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
Err(Determinacy::Determined)
}
}
WhereToResolve::DeriveHelpers => {
let mut result = Err(Determinacy::Determined);
for derive in &parent_scope.derives {
let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
if let Ok((_, ext)) = self.resolve_macro_to_def(derive, MacroKind::Derive,
&parent_scope, force) {
if let SyntaxExtension::ProcMacroDerive(_, helper_attrs, _) = &*ext {
if helper_attrs.contains(&ident.name) {
let binding =
(Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
ty::Visibility::Public, derive.span, Mark::root())
.to_name_binding(self.arenas);
result = Ok((binding, Flags::DERIVE_HELPERS, Flags::all()));
break;
}
}
}
}
result
}
WhereToResolve::LegacyPluginHelpers => {
if self.session.plugin_attributes.borrow().iter()
.any(|(name, _)| ident.name == &**name) {
Expand Down Expand Up @@ -747,6 +747,8 @@ impl<'a, 'cl> Resolver<'a, 'cl> {

macro_rules! continue_search { () => {
where_to_resolve = match where_to_resolve {
WhereToResolve::DeriveHelpers =>
WhereToResolve::MacroRules(parent_scope.legacy),
WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
LegacyScope::Binding(binding) =>
WhereToResolve::MacroRules(binding.parent_legacy_scope),
Expand All @@ -770,8 +772,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
}
WhereToResolve::MacroUsePrelude => WhereToResolve::BuiltinMacros,
WhereToResolve::BuiltinMacros => WhereToResolve::BuiltinAttrs,
WhereToResolve::BuiltinAttrs => WhereToResolve::DeriveHelpers,
WhereToResolve::DeriveHelpers => WhereToResolve::LegacyPluginHelpers,
WhereToResolve::BuiltinAttrs => WhereToResolve::LegacyPluginHelpers,
WhereToResolve::LegacyPluginHelpers => break, // nowhere else to search
WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
Expand Down

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