[ty] Resolve overloads for hovers

crates/ty_ide/src/goto.rs

@@ -15,7 +15,7 @@ use ruff_text_size::{Ranged, TextRange, TextSize};
 use ty_python_semantic::ResolvedDefinition;
 use ty_python_semantic::types::Type;
 use ty_python_semantic::types::ide_support::{
-    call_signature_details, definitions_for_keyword_argument,
+    call_signature_details, call_type_simplified_by_overloads, definitions_for_keyword_argument,
 };
 use ty_python_semantic::{
     HasDefinition, HasType, ImportAliasResolution, SemanticModel, definitions_for_imported_symbol,
@@ -326,6 +326,18 @@ impl GotoTarget<'_> {
         Some(ty)
     }
 
+    /// Try to get a simplified display of this callable type by resolving overloads
+    pub(crate) fn call_type_simplified_by_overloads(
+        &self,
+        model: &SemanticModel,
+    ) -> Option<String> {
+        if let GotoTarget::Call { call, .. } = self {
+            call_type_simplified_by_overloads(model.db(), model, call)
+        } else {
+            None
+        }
+    }
+
     /// Gets the definitions for this goto target.
     ///
     /// The `alias_resolution` parameter controls whether import aliases

crates/ty_ide/src/hover.rs

@@ -20,7 +20,6 @@ pub fn hover(db: &dyn Db, file: File, offset: TextSize) -> Option<RangedValue<Ho
     }
 
     let model = SemanticModel::new(db, file);
-    let ty = goto_target.inferred_type(&model);
     let docs = goto_target
         .get_definition_targets(
             file,
@@ -30,9 +29,10 @@ pub fn hover(db: &dyn Db, file: File, offset: TextSize) -> Option<RangedValue<Ho
         .and_then(|definitions| definitions.docstring(db))
         .map(HoverContent::Docstring);
 
-    // TODO: Render the symbol's signature instead of just its type.
     let mut contents = Vec::new();
-    if let Some(ty) = ty {
+    if let Some(signature) = goto_target.call_type_simplified_by_overloads(&model) {
+        contents.push(HoverContent::Signature(signature));
+    } else if let Some(ty) = goto_target.inferred_type(&model) {
         tracing::debug!("Inferred type of covering node is {}", ty.display(db));
         contents.push(match ty {
             Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) => typevar
@@ -62,7 +62,7 @@ pub struct Hover<'db> {
 
 impl<'db> Hover<'db> {
     /// Renders the hover to a string using the specified markup kind.
-    pub const fn display<'a>(&'a self, db: &'a dyn Db, kind: MarkupKind) -> DisplayHover<'a> {
+    pub const fn display<'a>(&'a self, db: &'db dyn Db, kind: MarkupKind) -> DisplayHover<'db, 'a> {
         DisplayHover {
             db,
             hover: self,
@@ -93,13 +93,13 @@ impl<'a, 'db> IntoIterator for &'a Hover<'db> {
     }
 }
 
-pub struct DisplayHover<'a> {
-    db: &'a dyn Db,
-    hover: &'a Hover<'a>,
+pub struct DisplayHover<'db, 'a> {
+    db: &'db dyn Db,
+    hover: &'a Hover<'db>,
     kind: MarkupKind,
 }
 
-impl fmt::Display for DisplayHover<'_> {
+impl fmt::Display for DisplayHover<'_, '_> {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         let mut first = true;
         for content in &self.hover.contents {
@@ -115,8 +115,9 @@ impl fmt::Display for DisplayHover<'_> {
     }
 }
 
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Clone)]
 pub enum HoverContent<'db> {
+    Signature(String),
     Type(Type<'db>, Option<TypeVarVariance>),
     Docstring(Docstring),
 }
@@ -140,6 +141,9 @@ pub(crate) struct DisplayHoverContent<'a, 'db> {
 impl fmt::Display for DisplayHoverContent<'_, '_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.content {
+            HoverContent::Signature(signature) => {
+                self.kind.fenced_code_block(&signature, "python").fmt(f)
+            }
             HoverContent::Type(ty, variance) => {
                 let variance = match variance {
                     Some(TypeVarVariance::Covariant) => " (covariant)",
@@ -961,14 +965,12 @@ def ab(a: str): ...
 
         assert_snapshot!(test.hover(), @r"
         (a: int) -> Unknown
-        (a: str) -> Unknown
         ---------------------------------------------
         the int overload
 
         ---------------------------------------------
         ```python
         (a: int) -> Unknown
-        (a: str) -> Unknown
         ```
         ---
         ```text
@@ -1025,14 +1027,12 @@ def ab(a: str):
             .build();
 
         assert_snapshot!(test.hover(), @r#"
-        (a: int) -> Unknown
         (a: str) -> Unknown
         ---------------------------------------------
         the int overload
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
         (a: str) -> Unknown
         ```
         ---
@@ -1094,7 +1094,6 @@ def ab(a: int):
             a: int,
             b: int
         ) -> Unknown
-        (a: int) -> Unknown
         ---------------------------------------------
         the two arg overload
 
@@ -1104,7 +1103,6 @@ def ab(a: int):
             a: int,
             b: int
         ) -> Unknown
-        (a: int) -> Unknown
         ```
         ---
         ```text
@@ -1161,20 +1159,12 @@ def ab(a: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (
-            a: int,
-            b: int
-        ) -> Unknown
         (a: int) -> Unknown
         ---------------------------------------------
         the two arg overload
 
         ---------------------------------------------
         ```python
-        (
-            a: int,
-            b: int
-        ) -> Unknown
         (a: int) -> Unknown
         ```
         ---
@@ -1236,33 +1226,21 @@ def ab(a: int, *, c: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (a: int) -> Unknown
         (
             a: int,
             *,
             b: int
         ) -> Unknown
-        (
-            a: int,
-            *,
-            c: int
-        ) -> Unknown
         ---------------------------------------------
         keywordless overload
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
         (
             a: int,
             *,
             b: int
         ) -> Unknown
-        (
-            a: int,
-            *,
-            c: int
-        ) -> Unknown
         ```
         ---
         ```text
@@ -1323,12 +1301,6 @@ def ab(a: int, *, c: int):
             .build();
 
         assert_snapshot!(test.hover(), @r"
-        (a: int) -> Unknown
-        (
-            a: int,
-            *,
-            b: int
-        ) -> Unknown
         (
             a: int,
             *,
@@ -1339,12 +1311,6 @@ def ab(a: int, *, c: int):
 
         ---------------------------------------------
         ```python
-        (a: int) -> Unknown
-        (
-            a: int,
-            *,
-            b: int
-        ) -> Unknown
         (
             a: int,
             *,

crates/ty_python_semantic/src/types/call/arguments.rs

@@ -66,6 +66,39 @@ impl<'a, 'db> CallArguments<'a, 'db> {
             .collect()
     }
 
+    /// Like [`Self::from_arguments`] but fills as much typing info in as possible.
+    ///
+    /// This currently only exists for the LSP usecase, and shouldn't be used in normal
+    /// typechecking.
+    pub(crate) fn from_arguments_typed(
+        arguments: &'a ast::Arguments,
+        mut infer_argument_type: impl FnMut(Option<&ast::Expr>, &ast::Expr) -> Type<'db>,
+    ) -> Self {
+        arguments
+            .arguments_source_order()
+            .map(|arg_or_keyword| match arg_or_keyword {
+                ast::ArgOrKeyword::Arg(arg) => match arg {
+                    ast::Expr::Starred(ast::ExprStarred { value, .. }) => {
+                        let ty = infer_argument_type(Some(arg), value);
+                        (Argument::Variadic, Some(ty))
+                    }
+                    _ => {
+                        let ty = infer_argument_type(None, arg);
+                        (Argument::Positional, Some(ty))
+                    }
+                },
+                ast::ArgOrKeyword::Keyword(ast::Keyword { arg, value, .. }) => {
+                    let ty = infer_argument_type(None, value);
+                    if let Some(arg) = arg {
+                        (Argument::Keyword(&arg.id), Some(ty))
+                    } else {
+                        (Argument::Keywords, Some(ty))
+                    }
+                }
+            })
+            .collect()
+    }
+
     /// Create a [`CallArguments`] with no arguments.
     pub(crate) fn none() -> Self {
         Self::default()

crates/ty_python_semantic/src/types/ide_support.rs

@@ -17,7 +17,7 @@ use crate::types::{
     ClassBase, ClassLiteral, DynamicType, KnownClass, KnownInstanceType, Type, TypeContext,
     TypeVarBoundOrConstraints, class::CodeGeneratorKind,
 };
-use crate::{Db, HasType, NameKind, SemanticModel};
+use crate::{Db, DisplaySettings, HasType, NameKind, SemanticModel};
 use ruff_db::files::{File, FileRange};
 use ruff_db::parsed::parsed_module;
 use ruff_python_ast::name::Name;
@@ -973,6 +973,65 @@ pub fn call_signature_details<'db>(
     }
 }
 
+/// Given a call expression that has overloads, and whose overload is resolved to a
+/// single option by its arguments, return the type of the Signature.
+///
+/// This is only used for simplifying complex call types, so if we ever detect that
+/// the given callable type *is* simple, or that our answer *won't* be simple, we
+/// bail at out and return None, so that the original type can be used.
+///
+/// We do this because `Type::Signature` intentionally loses a lot of context, and
+/// so it has a "worse" display than say `Type::FunctionLiteral` or `Type::BoundMethod`,
+/// which this analysis would naturally wipe away. The contexts this function
+/// succeeds in are those where we would print a complicated/ugly type anyway.
+pub fn call_type_simplified_by_overloads<'db>(
+    db: &'db dyn Db,
+    model: &SemanticModel<'db>,
+    call_expr: &ast::ExprCall,
+) -> Option<String> {
+    let func_type = call_expr.func.inferred_type(model);
+
+    // Use into_callable to handle all the complex type conversions
+    let callable_type = func_type.try_upcast_to_callable(db)?;
+    let bindings = callable_type.bindings(db);
+
+    // If the callable is trivial this analysis is useless, bail out
+    if let Some(binding) = bindings.single_element()
+        && binding.overloads().len() < 2
+    {
+        return None;
+    }
+
+    // Hand the overload resolution system as much type info as we have
+    let args = CallArguments::from_arguments_typed(&call_expr.arguments, |_, splatted_value| {
+        splatted_value.inferred_type(model)
+    });
+
+    // Try to resolve overloads with the arguments/types we have
+    let mut resolved = bindings
+        .match_parameters(db, &args)
+        .check_types(db, &args, TypeContext::default(), &[])
+        // Only use the Ok
+        .iter()
+        .flatten()
+        .flat_map(|binding| {
+            binding.matching_overloads().map(|(_, overload)| {
+                overload
+                    .signature
+                    .display_with(db, DisplaySettings::default().multiline())
+                    .to_string()
+            })
+        })
+        .collect::<Vec<_>>();
+
+    // If at the end of this we still got multiple signatures (or no signatures), give up
+    if resolved.len() != 1 {
+        return None;
+    }
+
+    resolved.pop()
+}
+
 /// Returns the definitions of the binary operation along with its callable type.
 pub fn definitions_for_bin_op<'db>(
     db: &'db dyn Db,