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Make PROC_MACRO_DERIVE_RESOLUTION_FALLBACK a hard error #84022

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Nov 1, 2022
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Make PROC_MACRO_DERIVE_RESOLUTION_FALLBACK a hard error #84022

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68 changes: 0 additions & 68 deletions compiler/rustc_lint_defs/src/builtin.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1982,73 +1982,6 @@ declare_lint! {
};
}

declare_lint! {
/// The `proc_macro_derive_resolution_fallback` lint detects proc macro
/// derives using inaccessible names from parent modules.
///
/// ### Example
///
/// ```rust,ignore (proc-macro)
/// // foo.rs
/// #![crate_type = "proc-macro"]
///
/// extern crate proc_macro;
///
/// use proc_macro::*;
///
/// #[proc_macro_derive(Foo)]
/// pub fn foo1(a: TokenStream) -> TokenStream {
/// drop(a);
/// "mod __bar { static mut BAR: Option<Something> = None; }".parse().unwrap()
/// }
/// ```
///
/// ```rust,ignore (needs-dependency)
/// // bar.rs
/// #[macro_use]
/// extern crate foo;
///
/// struct Something;
///
/// #[derive(Foo)]
/// struct Another;
///
/// fn main() {}
/// ```
///
/// This will produce:
///
/// ```text
/// warning: cannot find type `Something` in this scope
/// --> src/main.rs:8:10
/// |
/// 8 | #[derive(Foo)]
/// | ^^^ names from parent modules are not accessible without an explicit import
/// |
/// = note: `#[warn(proc_macro_derive_resolution_fallback)]` on by default
/// = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
/// = note: for more information, see issue #50504 <https://github.com/rust-lang/rust/issues/50504>
/// ```
///
/// ### Explanation
///
/// If a proc-macro generates a module, the compiler unintentionally
/// allowed items in that module to refer to items in the crate root
/// without importing them. This is a [future-incompatible] lint to
/// transition this to a hard error in the future. See [issue #50504] for
/// more details.
///
/// [issue #50504]: https://github.com/rust-lang/rust/issues/50504
/// [future-incompatible]: ../index.md#future-incompatible-lints
pub PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
Deny,
"detects proc macro derives using inaccessible names from parent modules",
@future_incompatible = FutureIncompatibleInfo {
reference: "issue #83583 <https://github.com/rust-lang/rust/issues/83583>",
reason: FutureIncompatibilityReason::FutureReleaseErrorReportNow,
};
}

declare_lint! {
/// The `macro_use_extern_crate` lint detects the use of the
/// [`macro_use` attribute].
Expand Down Expand Up @@ -3287,7 +3220,6 @@ declare_lint_pass! {
UNSTABLE_NAME_COLLISIONS,
IRREFUTABLE_LET_PATTERNS,
WHERE_CLAUSES_OBJECT_SAFETY,
PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
MACRO_USE_EXTERN_CRATE,
MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
ILL_FORMED_ATTRIBUTE_INPUT,
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_resolve/src/diagnostics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1186,7 +1186,7 @@ impl<'a> Resolver<'a> {
let root_module = this.resolve_crate_root(root_ident);
this.add_module_candidates(root_module, &mut suggestions, filter_fn, None);
}
Scope::Module(module, _) => {
Scope::Module(module) => {
this.add_module_candidates(module, &mut suggestions, filter_fn, None);
}
Scope::MacroUsePrelude => {
Expand Down
75 changes: 10 additions & 65 deletions compiler/rustc_resolve/src/ident.rs
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Original file line number Diff line number Diff line change
@@ -1,11 +1,9 @@
use rustc_ast::{self as ast, NodeId};
use rustc_ast as ast;
use rustc_feature::is_builtin_attr_name;
use rustc_hir::def::{DefKind, Namespace, NonMacroAttrKind, PartialRes, PerNS};
use rustc_hir::PrimTy;
use rustc_middle::bug;
use rustc_middle::ty;
use rustc_session::lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK;
use rustc_session::lint::BuiltinLintDiagnostics;
use rustc_span::def_id::LocalDefId;
use rustc_span::edition::Edition;
use rustc_span::hygiene::{ExpnId, ExpnKind, LocalExpnId, MacroKind, SyntaxContext};
Expand Down Expand Up @@ -101,7 +99,7 @@ impl<'a> Resolver<'a> {
};
let mut scope = match ns {
_ if is_absolute_path => Scope::CrateRoot,
TypeNS | ValueNS => Scope::Module(module, None),
TypeNS | ValueNS => Scope::Module(module),
MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
};
let mut ctxt = ctxt.normalize_to_macros_2_0();
Expand Down Expand Up @@ -165,7 +163,7 @@ impl<'a> Resolver<'a> {
MacroRulesScope::Invocation(invoc_id) => {
Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
}
MacroRulesScope::Empty => Scope::Module(module, None),
MacroRulesScope::Empty => Scope::Module(module),
},
Scope::CrateRoot => match ns {
TypeNS => {
Expand All @@ -174,16 +172,10 @@ impl<'a> Resolver<'a> {
}
ValueNS | MacroNS => break,
},
Scope::Module(module, prev_lint_id) => {
Scope::Module(module) => {
use_prelude = !module.no_implicit_prelude;
let derive_fallback_lint_id = match scope_set {
ScopeSet::Late(.., lint_id) => lint_id,
_ => None,
};
match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) {
Some((parent_module, lint_id)) => {
Scope::Module(parent_module, lint_id.or(prev_lint_id))
}
match self.hygienic_lexical_parent(module, &mut ctxt) {
Some(parent_module) => Scope::Module(parent_module),
None => {
ctxt.adjust(ExpnId::root());
match ns {
Expand Down Expand Up @@ -215,45 +207,13 @@ impl<'a> Resolver<'a> {
&mut self,
module: Module<'a>,
ctxt: &mut SyntaxContext,
derive_fallback_lint_id: Option<NodeId>,
) -> Option<(Module<'a>, Option<NodeId>)> {
) -> Option<Module<'a>> {
if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
return Some((self.expn_def_scope(ctxt.remove_mark()), None));
return Some(self.expn_def_scope(ctxt.remove_mark()));
}

if let ModuleKind::Block = module.kind {
return Some((module.parent.unwrap().nearest_item_scope(), None));
}

// We need to support the next case under a deprecation warning
// ```
// struct MyStruct;
// ---- begin: this comes from a proc macro derive
// mod implementation_details {
// // Note that `MyStruct` is not in scope here.
// impl SomeTrait for MyStruct { ... }
// }
// ---- end
// ```
// So we have to fall back to the module's parent during lexical resolution in this case.
if derive_fallback_lint_id.is_some() {
if let Some(parent) = module.parent {
// Inner module is inside the macro, parent module is outside of the macro.
if module.expansion != parent.expansion
&& module.expansion.is_descendant_of(parent.expansion)
{
// The macro is a proc macro derive
if let Some(def_id) = module.expansion.expn_data().macro_def_id {
let ext = self.get_macro_by_def_id(def_id).ext;
if ext.builtin_name.is_none()
&& ext.macro_kind() == MacroKind::Derive
&& parent.expansion.outer_expn_is_descendant_of(*ctxt)
{
return Some((parent, derive_fallback_lint_id));
}
}
}
}
return Some(module.parent.unwrap().nearest_item_scope());
}

None
Expand Down Expand Up @@ -510,7 +470,7 @@ impl<'a> Resolver<'a> {
Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
}
}
Scope::Module(module, derive_fallback_lint_id) => {
Scope::Module(module) => {
let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
let binding = this.resolve_ident_in_module_unadjusted_ext(
ModuleOrUniformRoot::Module(module),
Expand All @@ -523,21 +483,6 @@ impl<'a> Resolver<'a> {
);
match binding {
Ok(binding) => {
if let Some(lint_id) = derive_fallback_lint_id {
this.lint_buffer.buffer_lint_with_diagnostic(
PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
lint_id,
orig_ident.span,
&format!(
"cannot find {} `{}` in this scope",
ns.descr(),
ident
),
BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(
orig_ident.span,
),
);
}
let misc_flags = if ptr::eq(module, this.graph_root) {
Flags::MISC_SUGGEST_CRATE
} else if module.is_normal() {
Expand Down
6 changes: 2 additions & 4 deletions compiler/rustc_resolve/src/lib.rs
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Expand Up @@ -102,9 +102,7 @@ enum Scope<'a> {
DeriveHelpersCompat,
MacroRules(MacroRulesScopeRef<'a>),
CrateRoot,
// The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
// lint if it should be reported.
Module(Module<'a>, Option<NodeId>),
Module(Module<'a>),
MacroUsePrelude,
BuiltinAttrs,
ExternPrelude,
Expand Down Expand Up @@ -1551,7 +1549,7 @@ impl<'a> Resolver<'a> {

self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
match scope {
Scope::Module(module, _) => {
Scope::Module(module) => {
this.traits_in_module(module, assoc_item, &mut found_traits);
}
Scope::StdLibPrelude => {
Expand Down
7 changes: 2 additions & 5 deletions src/test/ui/proc-macro/generate-mod.rs
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Expand Up @@ -15,19 +15,16 @@ struct S;

#[derive(generate_mod::CheckDerive)] //~ ERROR cannot find type `FromOutside` in this scope
//~| ERROR cannot find type `OuterDerive` in this scope
//~| WARN this was previously accepted
//~| WARN this was previously accepted
struct Z;

fn inner_block() {
#[derive(generate_mod::CheckDerive)] //~ ERROR cannot find type `FromOutside` in this scope
//~| ERROR cannot find type `OuterDerive` in this scope
//~| WARN this was previously accepted
//~| WARN this was previously accepted
struct InnerZ;
}

#[derive(generate_mod::CheckDeriveLint)] // OK, lint is suppressed
#[derive(generate_mod::CheckDeriveLint)] //~ ERROR cannot find type `OuterDeriveLint` in this scope
//~| ERROR cannot find type `FromOutside` in this scope
struct W;

fn main() {}
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