Add necessary supplement to VarBindingForm

Author: ecstatic-morse

src/librustc_middle/lint.rs

@@ -12,7 +12,7 @@ use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
 use rustc_span::{Span, Symbol};
 
 /// How a lint level was set.
-#[derive(Clone, Copy, PartialEq, Eq, HashStable)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable)]
 pub enum LintSource {
     /// Lint is at the default level as declared
     /// in rustc or a plugin.

src/librustc_middle/mir/mod.rs

@@ -2,6 +2,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
 
+use crate::lint;
 use crate::mir::interpret::{GlobalAlloc, Scalar};
 use crate::mir::visit::MirVisitable;
 use crate::ty::adjustment::PointerCast;
@@ -14,7 +15,7 @@ use crate::ty::{
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, Namespace};
 use rustc_hir::def_id::DefId;
-use rustc_hir::{self, GeneratorKind};
+use rustc_hir::GeneratorKind;
 use rustc_target::abi::VariantIdx;
 
 use polonius_engine::Atom;
@@ -596,6 +597,22 @@ pub enum LocalKind {
 
 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
 pub struct VarBindingForm<'tcx> {
+    /// Bindings in match arms with guards are lowered to two distinct locals, one for inside the
+    /// guard and one for inside the match arm. If this local is the one used in the match arm,
+    /// `counterpart_in_guard` will be the local representing the same binding in the guard.
+    pub counterpart_in_guard: Option<Local>,
+
+    /// `true` if this variable was declared as a binding to a struct field with the same name
+    /// (e.g., `x` in `Foo { x }`).
+    pub is_shorthand_field_binding: bool,
+
+    /// The name of this variable.
+    pub name: Symbol,
+
+    pub unused_variables_lint_level: lint::LevelSource,
+
+    pub unused_assignments_lint_level: lint::LevelSource,
+
     /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
     pub binding_mode: ty::BindingMode,
     /// If an explicit type was provided for this variable binding,
@@ -845,9 +862,7 @@ impl<'tcx> LocalDecl<'tcx> {
         match self.local_info {
             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
                 binding_mode: ty::BindingMode::BindByValue(_),
-                opt_ty_info: _,
-                opt_match_place: _,
-                pat_span: _,
+                ..
             })))) => true,
 
             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(
@@ -865,9 +880,7 @@ impl<'tcx> LocalDecl<'tcx> {
         match self.local_info {
             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
                 binding_mode: ty::BindingMode::BindByValue(_),
-                opt_ty_info: _,
-                opt_match_place: _,
-                pat_span: _,
+                ..
             })))) => true,
 
             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_)))) => true,

src/librustc_mir/borrow_check/diagnostics/move_errors.rs

@@ -106,9 +106,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                         if let Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
                             VarBindingForm {
                                 opt_match_place: Some((opt_match_place, match_span)),
-                                binding_mode: _,
-                                opt_ty_info: _,
-                                pat_span: _,
+                                ..
                             },
                         )))) = local_decl.local_info
                         {

src/librustc_mir_build/build/matches/mod.rs

@@ -16,6 +16,7 @@ use rustc_index::bit_set::BitSet;
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty};
+use rustc_session::lint;
 use rustc_span::Span;
 use rustc_span::symbol::Symbol;
 use rustc_target::abi::VariantIdx;
@@ -1980,6 +1981,31 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             BindingMode::ByRef(_) => ty::BindingMode::BindByReference(mutability),
         };
         debug!("declare_binding: user_ty={:?}", user_ty);
+
+        let ref_for_guard = has_guard.0.then(|| {
+            let local = self.local_decls.push(LocalDecl::<'tcx> {
+                // This variable isn't mutated but has a name, so has to be
+                // immutable to avoid the unused mut lint.
+                mutability: Mutability::Not,
+                ty: tcx.mk_imm_ref(tcx.lifetimes.re_erased, var_ty),
+                user_ty: None,
+                source_info,
+                internal: false,
+                is_block_tail: None,
+                local_info: Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard))),
+            });
+            self.var_debug_info.push(VarDebugInfo {
+                name,
+                source_info: debug_source_info,
+                place: local.into(),
+            });
+            local
+        });
+
+        let name = tcx.hir().name(var_id);
+        let is_shorthand_field_binding = false;
+        let unused_variables_lint_level = tcx.lint_level_at_node(lint::builtin::UNUSED_VARIABLES, var_id);
+        let unused_assignments_lint_level = tcx.lint_level_at_node(lint::builtin::UNUSED_ASSIGNMENTS, var_id);
         let local = LocalDecl::<'tcx> {
             mutability,
             ty: var_ty,
@@ -1988,6 +2014,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             internal: false,
             is_block_tail: None,
             local_info: Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
+                unused_assignments_lint_level,
+                unused_variables_lint_level,
+                is_shorthand_field_binding,
+                counterpart_in_guard: ref_for_guard,
+                name,
                 binding_mode,
                 // hypothetically, `visit_primary_bindings` could try to unzip
                 // an outermost hir::Ty as we descend, matching up
@@ -2004,27 +2035,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             source_info: debug_source_info,
             place: for_arm_body.into(),
         });
-        let locals = if has_guard.0 {
-            let ref_for_guard = self.local_decls.push(LocalDecl::<'tcx> {
-                // This variable isn't mutated but has a name, so has to be
-                // immutable to avoid the unused mut lint.
-                mutability: Mutability::Not,
-                ty: tcx.mk_imm_ref(tcx.lifetimes.re_erased, var_ty),
-                user_ty: None,
-                source_info,
-                internal: false,
-                is_block_tail: None,
-                local_info: Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard))),
-            });
-            self.var_debug_info.push(VarDebugInfo {
-                name,
-                source_info: debug_source_info,
-                place: ref_for_guard.into(),
-            });
-            LocalsForNode::ForGuard { ref_for_guard, for_arm_body }
-        } else {
-            LocalsForNode::One(for_arm_body)
+
+        let locals = match ref_for_guard {
+            Some(ref_for_guard) => LocalsForNode::ForGuard { ref_for_guard, for_arm_body },
+            None => LocalsForNode::One(for_arm_body),
         };
+
         debug!("declare_binding: vars={:?}", locals);
         self.var_indices.insert(var_id, locals);
     }

src/librustc_mir_build/build/mod.rs

@@ -14,6 +14,7 @@ use rustc_middle::middle::region;
 use rustc_middle::mir::*;
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
+use rustc_session::lint;
 use rustc_span::symbol::kw;
 use rustc_span::Span;
 use rustc_target::spec::abi::Abi;
@@ -888,8 +889,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind))))
                         } else {
                             let binding_mode = ty::BindingMode::BindByValue(mutability);
+                            let unused_variables_lint_level = tcx.lint_level_at_node(lint::builtin::UNUSED_VARIABLES, var);
+                            let unused_assignments_lint_level = tcx.lint_level_at_node(lint::builtin::UNUSED_ASSIGNMENTS, var);
+                            let is_shorthand_field_binding = false;
+                            let name = tcx_hir.name(var);
                             Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
                                 VarBindingForm {
+                                    is_shorthand_field_binding,
+                                    counterpart_in_guard: None,
+                                    name,
+                                    unused_variables_lint_level,
+                                    unused_assignments_lint_level,
                                     binding_mode,
                                     opt_ty_info,
                                     opt_match_place: Some((Some(place), span)),

src/librustc_session/lint.rs

@@ -8,7 +8,7 @@ use rustc_span::{sym, symbol::Ident, MultiSpan, Span, Symbol};
 pub mod builtin;
 
 /// Setting for how to handle a lint.
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
+#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash, RustcEncodable, RustcDecodable)]
 pub enum Level {
     Allow,
     Warn,