Merge pull request #18934 from 1hakusai1/goto_definition_from_into

feat: Add the ability to jump from `into` to `from` definitions

crates/hir-expand/src/mod_path.rs

@@ -398,6 +398,9 @@ macro_rules! __known_path {
     (core::fmt::Debug) => {};
     (std::fmt::format) => {};
     (core::ops::Try) => {};
+    (core::convert::From) => {};
+    (core::convert::TryFrom) => {};
+    (core::str::FromStr) => {};
     ($path:path) => {
         compile_error!("Please register your known path in the path module")
     };

crates/hir/src/semantics.rs

@@ -1439,6 +1439,10 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(call.syntax())?.resolve_method_call_fallback(self.db, call)
     }
 
+    pub fn resolve_known_blanket_dual_impls(&self, call: &ast::MethodCallExpr) -> Option<Function> {
+        self.analyze(call.syntax())?.resolve_known_blanket_dual_impls(self.db, call)
+    }
+
     fn resolve_range_pat(&self, range_pat: &ast::RangePat) -> Option<StructId> {
         self.analyze(range_pat.syntax())?.resolve_range_pat(self.db, range_pat)
     }

crates/hir/src/source_analyzer.rs

@@ -322,6 +322,68 @@ impl SourceAnalyzer {
         }
     }
 
+    // If the method is into(), try_into(), parse(), resolve it to from, try_from, from_str.
+    pub(crate) fn resolve_known_blanket_dual_impls(
+        &self,
+        db: &dyn HirDatabase,
+        call: &ast::MethodCallExpr,
+    ) -> Option<Function> {
+        // e.g. if the method call is let b = a.into(),
+        // - receiver_type is A (type of a)
+        // - return_type is B (type of b)
+        // We will find the definition of B::from(a: A).
+        let callable = self.resolve_method_call_as_callable(db, call)?;
+        let (_, receiver_type) = callable.receiver_param(db)?;
+        let return_type = callable.return_type();
+        let (search_method, substs) = match call.name_ref()?.text().as_str() {
+            "into" => {
+                let trait_ =
+                    self.resolver.resolve_known_trait(db.upcast(), &path![core::convert::From])?;
+                (
+                    self.trait_fn(db, trait_, "from")?,
+                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
+                        .push(return_type.ty)
+                        .push(receiver_type.ty)
+                        .build(),
+                )
+            }
+            "try_into" => {
+                let trait_ = self
+                    .resolver
+                    .resolve_known_trait(db.upcast(), &path![core::convert::TryFrom])?;
+                (
+                    self.trait_fn(db, trait_, "try_from")?,
+                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
+                        // If the method is try_into() or parse(), return_type is Result<T, Error>.
+                        // Get T from type arguments of Result<T, Error>.
+                        .push(return_type.type_arguments().next()?.ty)
+                        .push(receiver_type.ty)
+                        .build(),
+                )
+            }
+            "parse" => {
+                let trait_ =
+                    self.resolver.resolve_known_trait(db.upcast(), &path![core::str::FromStr])?;
+                (
+                    self.trait_fn(db, trait_, "from_str")?,
+                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
+                        .push(return_type.type_arguments().next()?.ty)
+                        .build(),
+                )
+            }
+            _ => return None,
+        };
+
+        let found_method = self.resolve_impl_method_or_trait_def(db, search_method, substs);
+        // If found_method == search_method, the method in trait itself is resolved.
+        // It means the blanket dual impl is not found.
+        if found_method == search_method {
+            None
+        } else {
+            Some(found_method.into())
+        }
+    }
+
     pub(crate) fn resolve_expr_as_callable(
         &self,
         db: &dyn HirDatabase,
@@ -1247,6 +1309,18 @@ impl SourceAnalyzer {
         Some((trait_id, fn_id))
     }
 
+    fn trait_fn(
+        &self,
+        db: &dyn HirDatabase,
+        trait_id: TraitId,
+        method_name: &str,
+    ) -> Option<FunctionId> {
+        db.trait_data(trait_id).items.iter().find_map(|(item_name, item)| match item {
+            AssocItemId::FunctionId(t) if item_name.as_str() == method_name => Some(*t),
+            _ => None,
+        })
+    }
+
     fn ty_of_expr(&self, db: &dyn HirDatabase, expr: &ast::Expr) -> Option<&Ty> {
         self.infer.as_ref()?.type_of_expr_or_pat(self.expr_id(db, expr)?)
     }

crates/ide/src/goto_definition.rs

@@ -81,6 +81,10 @@ pub(crate) fn goto_definition(
         return Some(RangeInfo::new(original_token.text_range(), navs));
     }
 
+    if let Some(navs) = find_definition_for_known_blanket_dual_impls(sema, &original_token) {
+        return Some(RangeInfo::new(original_token.text_range(), navs));
+    }
+
     let navs = sema
         .descend_into_macros_no_opaque(original_token.clone())
         .into_iter()
@@ -125,6 +129,18 @@ pub(crate) fn goto_definition(
     Some(RangeInfo::new(original_token.text_range(), navs))
 }
 
+// If the token is into(), try_into(), parse(), search the definition of From, TryFrom, FromStr.
+fn find_definition_for_known_blanket_dual_impls(
+    sema: &Semantics<'_, RootDatabase>,
+    original_token: &SyntaxToken,
+) -> Option<Vec<NavigationTarget>> {
+    let method_call = ast::MethodCallExpr::cast(original_token.parent()?.parent()?)?;
+    let target_method = sema.resolve_known_blanket_dual_impls(&method_call)?;
+
+    let def = Definition::from(target_method);
+    Some(def_to_nav(sema.db, def))
+}
+
 fn try_lookup_include_path(
     sema: &Semantics<'_, RootDatabase>,
     token: ast::String,
@@ -3022,4 +3038,150 @@ fn foo() {
 "#,
         );
     }
+    #[test]
+    fn into_call_to_from_definition() {
+        check(
+            r#"
+//- minicore: from
+struct A;
+
+struct B;
+
+impl From<A> for B {
+    fn from(value: A) -> Self {
+     //^^^^
+        B
+    }
+}
+
+fn f() {
+    let a = A;
+    let b: B = a.into$0();
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn into_call_to_from_definition_with_trait_bounds() {
+        check(
+            r#"
+//- minicore: from, iterator
+struct A;
+
+impl<T> From<T> for A
+where
+    T: IntoIterator<Item = i64>,
+{
+    fn from(value: T) -> Self {
+     //^^^^
+        A
+    }
+}
+
+fn f() {
+    let a: A = [1, 2, 3].into$0();
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn goto_into_definition_if_exists() {
+        check(
+            r#"
+//- minicore: from
+struct A;
+
+struct B;
+
+impl Into<B> for A {
+    fn into(self) -> B {
+     //^^^^
+        B
+    }
+}
+
+fn f() {
+    let a = A;
+    let b: B = a.into$0();
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn try_into_call_to_try_from_definition() {
+        check(
+            r#"
+//- minicore: from
+struct A;
+
+struct B;
+
+impl TryFrom<A> for B {
+    type Error = String;
+
+    fn try_from(value: A) -> Result<Self, Self::Error> {
+     //^^^^^^^^
+        Ok(B)
+    }
+}
+
+fn f() {
+    let a = A;
+    let b: Result<B, _> = a.try_into$0();
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn goto_try_into_definition_if_exists() {
+        check(
+            r#"
+//- minicore: from
+struct A;
+
+struct B;
+
+impl TryInto<B> for A {
+    type Error = String;
+
+    fn try_into(self) -> Result<B, Self::Error> {
+     //^^^^^^^^
+        Ok(B)
+    }
+}
+
+fn f() {
+    let a = A;
+    let b: Result<B, _> = a.try_into$0();
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn parse_call_to_from_str_definition() {
+        check(
+            r#"
+//- minicore: from, str
+struct A;
+
+impl FromStr for A {
+    type Error = String;
+
+    fn from_str(value: &str) -> Result<Self, Self::Error> {
+     //^^^^^^^^
+        Ok(A)
+    }
+}
+
+fn f() {
+    let a: Result<A, _> = "aaaaaa".parse$0();
+}
+        "#,
+        );
+    }
 }

crates/intern/src/symbol/symbols.rs

@@ -174,6 +174,7 @@ define_symbols! {
     const_param_ty,
     Context,
     Continue,
+    convert,
     copy,
     Copy,
     core_panic,
@@ -239,6 +240,8 @@ define_symbols! {
     format_unsafe_arg,
     format,
     freeze,
+    From,
+    FromStr,
     from_output,
     from_residual,
     from_usize,
@@ -457,6 +460,7 @@ define_symbols! {
     transmute_trait,
     transparent,
     Try,
+    TryFrom,
     tuple_trait,
     u128,
     u16,

crates/test-utils/src/minicore.rs

@@ -32,7 +32,7 @@
 //!     error: fmt
 //!     fmt: option, result, transmute, coerce_unsized, copy, clone, derive
 //!     fn: tuple
-//!     from: sized
+//!     from: sized, result
 //!     future: pin
 //!     coroutine: pin
 //!     dispatch_from_dyn: unsize, pin
@@ -332,6 +332,25 @@ pub mod convert {
             t
         }
     }
+
+    pub trait TryFrom<T>: Sized {
+        type Error;
+        fn try_from(value: T) -> Result<Self, Self::Error>;
+    }
+    pub trait TryInto<T>: Sized {
+        type Error;
+        fn try_into(self) -> Result<T, Self::Error>;
+    }
+
+    impl<T, U> TryInto<U> for T
+    where
+        U: TryFrom<T>,
+    {
+        type Error = U::Error;
+        fn try_into(self) -> Result<U, U::Error> {
+            U::try_from(self)
+        }
+    }
     // endregion:from
 
     // region:as_ref
@@ -1555,6 +1574,15 @@ pub mod str {
     pub const unsafe fn from_utf8_unchecked(v: &[u8]) -> &str {
         ""
     }
+    pub trait FromStr: Sized {
+        type Err;
+        fn from_str(s: &str) -> Result<Self, Self::Err>;
+    }
+    impl str {
+        pub fn parse<F: FromStr>(&self) -> Result<F, F::Err> {
+            FromStr::from_str(self)
+        }
+    }
 }
 // endregion:str
 
@@ -1814,7 +1842,7 @@ pub mod prelude {
             cmp::{Eq, PartialEq},                    // :eq
             cmp::{Ord, PartialOrd},                  // :ord
             convert::AsRef,                          // :as_ref
-            convert::{From, Into},                   // :from
+            convert::{From, Into, TryFrom, TryInto}, // :from
             default::Default,                        // :default
             iter::{IntoIterator, Iterator},          // :iterator
             macros::builtin::{derive, derive_const}, // :derive
@@ -1829,6 +1857,7 @@ pub mod prelude {
             option::Option::{self, None, Some},      // :option
             panic,                                   // :panic
             result::Result::{self, Err, Ok},         // :result
+            str::FromStr,                            // :str
         };
     }