Auto merge of rust-lang#12948 - Veykril:classify-ops, r=Veykril

feat: Handle operators like their trait functions in the IDE

Allows hover and goto implementation to work on `?`, indexing brackets, binary operators, prefix operators and `await`. Regarding `await`, hover will continue to show the keyword docs while goto implementation will bring the user to the `poll` function of the `Future` implementation.
![Code_CJmZ3FGFVn](https://user-images.githubusercontent.com/3757771/183076683-c9899bd6-60d3-461b-965f-0c0f9745e2e8.gif)

Fixes rust-lang/rust-analyzer#12810

Author: bors

crates/hir-expand/src/name.rs

@@ -381,6 +381,7 @@ pub mod known {
         bitor,
         bitxor_assign,
         bitxor,
+        branch,
         deref_mut,
         deref,
         div_assign,
@@ -396,6 +397,7 @@ pub mod known {
         not,
         owned_box,
         partial_ord,
+        poll,
         r#fn,
         rem_assign,
         rem,

crates/hir-ty/src/infer/expr.rs

@@ -10,13 +10,13 @@ use chalk_ir::{
     cast::Cast, fold::Shift, DebruijnIndex, GenericArgData, Mutability, TyVariableKind,
 };
 use hir_def::{
-    expr::{ArithOp, Array, BinaryOp, CmpOp, Expr, ExprId, Literal, Ordering, Statement, UnaryOp},
+    expr::{ArithOp, Array, BinaryOp, CmpOp, Expr, ExprId, Literal, Statement, UnaryOp},
     generics::TypeOrConstParamData,
     path::{GenericArg, GenericArgs},
     resolver::resolver_for_expr,
-    ConstParamId, FieldId, FunctionId, ItemContainerId, Lookup,
+    ConstParamId, FieldId, ItemContainerId, Lookup,
 };
-use hir_expand::name::{name, Name};
+use hir_expand::name::Name;
 use stdx::always;
 use syntax::ast::RangeOp;
 
@@ -28,7 +28,7 @@ use crate::{
         const_or_path_to_chalk, generic_arg_to_chalk, lower_to_chalk_mutability, ParamLoweringMode,
     },
     mapping::{from_chalk, ToChalk},
-    method_resolution::{self, VisibleFromModule},
+    method_resolution::{self, lang_names_for_bin_op, VisibleFromModule},
     primitive::{self, UintTy},
     static_lifetime, to_chalk_trait_id,
     utils::{generics, Generics},
@@ -947,7 +947,9 @@ impl<'a> InferenceContext<'a> {
         let lhs_ty = self.infer_expr(lhs, &lhs_expectation);
         let rhs_ty = self.table.new_type_var();
 
-        let func = self.resolve_binop_method(op);
+        let func = lang_names_for_bin_op(op).and_then(|(name, lang_item)| {
+            self.db.trait_data(self.resolve_lang_item(lang_item)?.as_trait()?).method_by_name(&name)
+        });
         let func = match func {
             Some(func) => func,
             None => {
@@ -1473,55 +1475,4 @@ impl<'a> InferenceContext<'a> {
             },
         })
     }
-
-    fn resolve_binop_method(&self, op: BinaryOp) -> Option<FunctionId> {
-        let (name, lang_item) = match op {
-            BinaryOp::LogicOp(_) => return None,
-            BinaryOp::ArithOp(aop) => match aop {
-                ArithOp::Add => (name!(add), name!(add)),
-                ArithOp::Mul => (name!(mul), name!(mul)),
-                ArithOp::Sub => (name!(sub), name!(sub)),
-                ArithOp::Div => (name!(div), name!(div)),
-                ArithOp::Rem => (name!(rem), name!(rem)),
-                ArithOp::Shl => (name!(shl), name!(shl)),
-                ArithOp::Shr => (name!(shr), name!(shr)),
-                ArithOp::BitXor => (name!(bitxor), name!(bitxor)),
-                ArithOp::BitOr => (name!(bitor), name!(bitor)),
-                ArithOp::BitAnd => (name!(bitand), name!(bitand)),
-            },
-            BinaryOp::Assignment { op: Some(aop) } => match aop {
-                ArithOp::Add => (name!(add_assign), name!(add_assign)),
-                ArithOp::Mul => (name!(mul_assign), name!(mul_assign)),
-                ArithOp::Sub => (name!(sub_assign), name!(sub_assign)),
-                ArithOp::Div => (name!(div_assign), name!(div_assign)),
-                ArithOp::Rem => (name!(rem_assign), name!(rem_assign)),
-                ArithOp::Shl => (name!(shl_assign), name!(shl_assign)),
-                ArithOp::Shr => (name!(shr_assign), name!(shr_assign)),
-                ArithOp::BitXor => (name!(bitxor_assign), name!(bitxor_assign)),
-                ArithOp::BitOr => (name!(bitor_assign), name!(bitor_assign)),
-                ArithOp::BitAnd => (name!(bitand_assign), name!(bitand_assign)),
-            },
-            BinaryOp::CmpOp(cop) => match cop {
-                CmpOp::Eq { negated: false } => (name!(eq), name!(eq)),
-                CmpOp::Eq { negated: true } => (name!(ne), name!(eq)),
-                CmpOp::Ord { ordering: Ordering::Less, strict: false } => {
-                    (name!(le), name!(partial_ord))
-                }
-                CmpOp::Ord { ordering: Ordering::Less, strict: true } => {
-                    (name!(lt), name!(partial_ord))
-                }
-                CmpOp::Ord { ordering: Ordering::Greater, strict: false } => {
-                    (name!(ge), name!(partial_ord))
-                }
-                CmpOp::Ord { ordering: Ordering::Greater, strict: true } => {
-                    (name!(gt), name!(partial_ord))
-                }
-            },
-            BinaryOp::Assignment { op: None } => return None,
-        };
-
-        let trait_ = self.resolve_lang_item(lang_item)?.as_trait()?;
-
-        self.db.trait_data(trait_).method_by_name(&name)
-    }
 }

crates/hir-ty/src/method_resolution.rs

@@ -336,7 +336,7 @@ impl InherentImpls {
     }
 }
 
-pub fn inherent_impl_crates_query(
+pub(crate) fn inherent_impl_crates_query(
     db: &dyn HirDatabase,
     krate: CrateId,
     fp: TyFingerprint,
@@ -419,6 +419,55 @@ pub fn def_crates(
     }
 }
 
+pub fn lang_names_for_bin_op(op: syntax::ast::BinaryOp) -> Option<(Name, Name)> {
+    use hir_expand::name;
+    use syntax::ast::{ArithOp, BinaryOp, CmpOp, Ordering};
+    Some(match op {
+        BinaryOp::LogicOp(_) => return None,
+        BinaryOp::ArithOp(aop) => match aop {
+            ArithOp::Add => (name!(add), name!(add)),
+            ArithOp::Mul => (name!(mul), name!(mul)),
+            ArithOp::Sub => (name!(sub), name!(sub)),
+            ArithOp::Div => (name!(div), name!(div)),
+            ArithOp::Rem => (name!(rem), name!(rem)),
+            ArithOp::Shl => (name!(shl), name!(shl)),
+            ArithOp::Shr => (name!(shr), name!(shr)),
+            ArithOp::BitXor => (name!(bitxor), name!(bitxor)),
+            ArithOp::BitOr => (name!(bitor), name!(bitor)),
+            ArithOp::BitAnd => (name!(bitand), name!(bitand)),
+        },
+        BinaryOp::Assignment { op: Some(aop) } => match aop {
+            ArithOp::Add => (name!(add_assign), name!(add_assign)),
+            ArithOp::Mul => (name!(mul_assign), name!(mul_assign)),
+            ArithOp::Sub => (name!(sub_assign), name!(sub_assign)),
+            ArithOp::Div => (name!(div_assign), name!(div_assign)),
+            ArithOp::Rem => (name!(rem_assign), name!(rem_assign)),
+            ArithOp::Shl => (name!(shl_assign), name!(shl_assign)),
+            ArithOp::Shr => (name!(shr_assign), name!(shr_assign)),
+            ArithOp::BitXor => (name!(bitxor_assign), name!(bitxor_assign)),
+            ArithOp::BitOr => (name!(bitor_assign), name!(bitor_assign)),
+            ArithOp::BitAnd => (name!(bitand_assign), name!(bitand_assign)),
+        },
+        BinaryOp::CmpOp(cop) => match cop {
+            CmpOp::Eq { negated: false } => (name!(eq), name!(eq)),
+            CmpOp::Eq { negated: true } => (name!(ne), name!(eq)),
+            CmpOp::Ord { ordering: Ordering::Less, strict: false } => {
+                (name!(le), name!(partial_ord))
+            }
+            CmpOp::Ord { ordering: Ordering::Less, strict: true } => {
+                (name!(lt), name!(partial_ord))
+            }
+            CmpOp::Ord { ordering: Ordering::Greater, strict: false } => {
+                (name!(ge), name!(partial_ord))
+            }
+            CmpOp::Ord { ordering: Ordering::Greater, strict: true } => {
+                (name!(gt), name!(partial_ord))
+            }
+        },
+        BinaryOp::Assignment { op: None } => return None,
+    })
+}
+
 /// Look up the method with the given name.
 pub(crate) fn lookup_method(
     ty: &Canonical<Ty>,

crates/hir/src/semantics.rs

@@ -357,6 +357,26 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.resolve_method_call(call).map(Function::from)
     }
 
+    pub fn resolve_await_to_poll(&self, await_expr: &ast::AwaitExpr) -> Option<Function> {
+        self.imp.resolve_await_to_poll(await_expr).map(Function::from)
+    }
+
+    pub fn resolve_prefix_expr(&self, prefix_expr: &ast::PrefixExpr) -> Option<Function> {
+        self.imp.resolve_prefix_expr(prefix_expr).map(Function::from)
+    }
+
+    pub fn resolve_index_expr(&self, index_expr: &ast::IndexExpr) -> Option<Function> {
+        self.imp.resolve_index_expr(index_expr).map(Function::from)
+    }
+
+    pub fn resolve_bin_expr(&self, bin_expr: &ast::BinExpr) -> Option<Function> {
+        self.imp.resolve_bin_expr(bin_expr).map(Function::from)
+    }
+
+    pub fn resolve_try_expr(&self, try_expr: &ast::TryExpr) -> Option<Function> {
+        self.imp.resolve_try_expr(try_expr).map(Function::from)
+    }
+
     pub fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
         self.imp.resolve_method_call_as_callable(call)
     }
@@ -1066,6 +1086,26 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(call.syntax())?.resolve_method_call(self.db, call)
     }
 
+    fn resolve_await_to_poll(&self, await_expr: &ast::AwaitExpr) -> Option<FunctionId> {
+        self.analyze(await_expr.syntax())?.resolve_await_to_poll(self.db, await_expr)
+    }
+
+    fn resolve_prefix_expr(&self, prefix_expr: &ast::PrefixExpr) -> Option<FunctionId> {
+        self.analyze(prefix_expr.syntax())?.resolve_prefix_expr(self.db, prefix_expr)
+    }
+
+    fn resolve_index_expr(&self, index_expr: &ast::IndexExpr) -> Option<FunctionId> {
+        self.analyze(index_expr.syntax())?.resolve_index_expr(self.db, index_expr)
+    }
+
+    fn resolve_bin_expr(&self, bin_expr: &ast::BinExpr) -> Option<FunctionId> {
+        self.analyze(bin_expr.syntax())?.resolve_bin_expr(self.db, bin_expr)
+    }
+
+    fn resolve_try_expr(&self, try_expr: &ast::TryExpr) -> Option<FunctionId> {
+        self.analyze(try_expr.syntax())?.resolve_try_expr(self.db, try_expr)
+    }
+
     fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
         self.analyze(call.syntax())?.resolve_method_call_as_callable(self.db, call)
     }

crates/hir/src/source_analyzer.rs

@@ -25,15 +25,20 @@ use hir_def::{
     Lookup, ModuleDefId, VariantId,
 };
 use hir_expand::{
-    builtin_fn_macro::BuiltinFnLikeExpander, hygiene::Hygiene, name::AsName, HirFileId, InFile,
+    builtin_fn_macro::BuiltinFnLikeExpander,
+    hygiene::Hygiene,
+    name,
+    name::{AsName, Name},
+    HirFileId, InFile,
 };
 use hir_ty::{
     diagnostics::{
         record_literal_missing_fields, record_pattern_missing_fields, unsafe_expressions,
         UnsafeExpr,
     },
-    method_resolution, Adjust, Adjustment, AutoBorrow, InferenceResult, Interner, Substitution,
-    TyExt, TyKind, TyLoweringContext,
+    method_resolution::{self, lang_names_for_bin_op},
+    Adjust, Adjustment, AutoBorrow, InferenceResult, Interner, Substitution, Ty, TyExt, TyKind,
+    TyLoweringContext,
 };
 use itertools::Itertools;
 use smallvec::SmallVec;
@@ -255,8 +260,90 @@ impl SourceAnalyzer {
     ) -> Option<FunctionId> {
         let expr_id = self.expr_id(db, &call.clone().into())?;
         let (f_in_trait, substs) = self.infer.as_ref()?.method_resolution(expr_id)?;
-        let f_in_impl = self.resolve_impl_method(db, f_in_trait, &substs);
-        f_in_impl.or(Some(f_in_trait))
+
+        Some(self.resolve_impl_method_or_trait_def(db, f_in_trait, &substs))
+    }
+
+    pub(crate) fn resolve_await_to_poll(
+        &self,
+        db: &dyn HirDatabase,
+        await_expr: &ast::AwaitExpr,
+    ) -> Option<FunctionId> {
+        let ty = self.ty_of_expr(db, &await_expr.expr()?.into())?;
+
+        let op_fn = db
+            .lang_item(self.resolver.krate(), hir_expand::name![poll].to_smol_str())?
+            .as_function()?;
+        let substs = hir_ty::TyBuilder::subst_for_def(db, op_fn).push(ty.clone()).build();
+
+        Some(self.resolve_impl_method_or_trait_def(db, op_fn, &substs))
+    }
+
+    pub(crate) fn resolve_prefix_expr(
+        &self,
+        db: &dyn HirDatabase,
+        prefix_expr: &ast::PrefixExpr,
+    ) -> Option<FunctionId> {
+        let lang_item_name = match prefix_expr.op_kind()? {
+            ast::UnaryOp::Deref => name![deref],
+            ast::UnaryOp::Not => name![not],
+            ast::UnaryOp::Neg => name![neg],
+        };
+        let ty = self.ty_of_expr(db, &prefix_expr.expr()?.into())?;
+
+        let op_fn = self.lang_trait_fn(db, &lang_item_name, &lang_item_name)?;
+        let substs = hir_ty::TyBuilder::subst_for_def(db, op_fn).push(ty.clone()).build();
+
+        Some(self.resolve_impl_method_or_trait_def(db, op_fn, &substs))
+    }
+
+    pub(crate) fn resolve_index_expr(
+        &self,
+        db: &dyn HirDatabase,
+        index_expr: &ast::IndexExpr,
+    ) -> Option<FunctionId> {
+        let base_ty = self.ty_of_expr(db, &index_expr.base()?.into())?;
+        let index_ty = self.ty_of_expr(db, &index_expr.index()?.into())?;
+
+        let lang_item_name = name![index];
+
+        let op_fn = self.lang_trait_fn(db, &lang_item_name, &lang_item_name)?;
+        let substs = hir_ty::TyBuilder::subst_for_def(db, op_fn)
+            .push(base_ty.clone())
+            .push(index_ty.clone())
+            .build();
+        Some(self.resolve_impl_method_or_trait_def(db, op_fn, &substs))
+    }
+
+    pub(crate) fn resolve_bin_expr(
+        &self,
+        db: &dyn HirDatabase,
+        binop_expr: &ast::BinExpr,
+    ) -> Option<FunctionId> {
+        let op = binop_expr.op_kind()?;
+        let lhs = self.ty_of_expr(db, &binop_expr.lhs()?.into())?;
+        let rhs = self.ty_of_expr(db, &binop_expr.rhs()?.into())?;
+
+        let op_fn = lang_names_for_bin_op(op)
+            .and_then(|(name, lang_item)| self.lang_trait_fn(db, &lang_item, &name))?;
+        let substs =
+            hir_ty::TyBuilder::subst_for_def(db, op_fn).push(lhs.clone()).push(rhs.clone()).build();
+
+        Some(self.resolve_impl_method_or_trait_def(db, op_fn, &substs))
+    }
+
+    pub(crate) fn resolve_try_expr(
+        &self,
+        db: &dyn HirDatabase,
+        try_expr: &ast::TryExpr,
+    ) -> Option<FunctionId> {
+        let ty = self.ty_of_expr(db, &try_expr.expr()?.into())?;
+
+        let op_fn =
+            db.lang_item(self.resolver.krate(), name![branch].to_smol_str())?.as_function()?;
+        let substs = hir_ty::TyBuilder::subst_for_def(db, op_fn).push(ty.clone()).build();
+
+        Some(self.resolve_impl_method_or_trait_def(db, op_fn, &substs))
     }
 
     pub(crate) fn resolve_field(
@@ -666,6 +753,29 @@ impl SourceAnalyzer {
         let fun_data = db.function_data(func);
         method_resolution::lookup_impl_method(self_ty, db, trait_env, impled_trait, &fun_data.name)
     }
+
+    fn resolve_impl_method_or_trait_def(
+        &self,
+        db: &dyn HirDatabase,
+        func: FunctionId,
+        substs: &Substitution,
+    ) -> FunctionId {
+        self.resolve_impl_method(db, func, substs).unwrap_or(func)
+    }
+
+    fn lang_trait_fn(
+        &self,
+        db: &dyn HirDatabase,
+        lang_trait: &Name,
+        method_name: &Name,
+    ) -> Option<FunctionId> {
+        db.trait_data(db.lang_item(self.resolver.krate(), lang_trait.to_smol_str())?.as_trait()?)
+            .method_by_name(method_name)
+    }
+
+    fn ty_of_expr(&self, db: &dyn HirDatabase, expr: &ast::Expr) -> Option<&Ty> {
+        self.infer.as_ref()?.type_of_expr.get(self.expr_id(db, &expr)?)
+    }
 }
 
 fn scope_for(