Auto merge of rust-lang#17364 - roife:fix-issue-12917, r=Veykril

feat: show type bounds from containers when hovering on functions

fix rust-lang#12917.

### Changes

1. Added Support for displaying the container and type bounds from it when hovering on functions with generic types.
2. Added a user config to determine whether to display container bounds (enabled by default).
3. Added regression tests.
4. Simplified and refactored `hir/display.rs` to improve readability.

Author: bors

src/tools/rust-analyzer/Cargo.lock

@@ -512,6 +512,7 @@ dependencies = [
  "hir-def",
  "hir-expand",
  "hir-ty",
+ "intern",
  "itertools",
  "once_cell",
  "rustc-hash",

src/tools/rust-analyzer/crates/hir-ty/src/display.rs

@@ -74,6 +74,8 @@ pub struct HirFormatter<'a> {
     /// When rendering something that has a concept of "children" (like fields in a struct), this limits
     /// how many should be rendered.
     pub entity_limit: Option<usize>,
+    /// When rendering functions, whether to show the constraint from the container
+    show_container_bounds: bool,
     omit_verbose_types: bool,
     closure_style: ClosureStyle,
     display_target: DisplayTarget,
@@ -101,6 +103,7 @@ pub trait HirDisplay {
         omit_verbose_types: bool,
         display_target: DisplayTarget,
         closure_style: ClosureStyle,
+        show_container_bounds: bool,
     ) -> HirDisplayWrapper<'a, Self>
     where
         Self: Sized,
@@ -117,6 +120,7 @@ pub trait HirDisplay {
             omit_verbose_types,
             display_target,
             closure_style,
+            show_container_bounds,
         }
     }
 
@@ -134,6 +138,7 @@ pub trait HirDisplay {
             omit_verbose_types: false,
             closure_style: ClosureStyle::ImplFn,
             display_target: DisplayTarget::Diagnostics,
+            show_container_bounds: false,
         }
     }
 
@@ -155,6 +160,7 @@ pub trait HirDisplay {
             omit_verbose_types: true,
             closure_style: ClosureStyle::ImplFn,
             display_target: DisplayTarget::Diagnostics,
+            show_container_bounds: false,
         }
     }
 
@@ -176,6 +182,7 @@ pub trait HirDisplay {
             omit_verbose_types: true,
             closure_style: ClosureStyle::ImplFn,
             display_target: DisplayTarget::Diagnostics,
+            show_container_bounds: false,
         }
     }
 
@@ -198,6 +205,7 @@ pub trait HirDisplay {
             omit_verbose_types: false,
             closure_style: ClosureStyle::ImplFn,
             display_target: DisplayTarget::SourceCode { module_id, allow_opaque },
+            show_container_bounds: false,
         }) {
             Ok(()) => {}
             Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
@@ -219,6 +227,29 @@ pub trait HirDisplay {
             omit_verbose_types: false,
             closure_style: ClosureStyle::ImplFn,
             display_target: DisplayTarget::Test,
+            show_container_bounds: false,
+        }
+    }
+
+    /// Returns a String representation of `self` that shows the constraint from
+    /// the container for functions
+    fn display_with_container_bounds<'a>(
+        &'a self,
+        db: &'a dyn HirDatabase,
+        show_container_bounds: bool,
+    ) -> HirDisplayWrapper<'a, Self>
+    where
+        Self: Sized,
+    {
+        HirDisplayWrapper {
+            db,
+            t: self,
+            max_size: None,
+            limited_size: None,
+            omit_verbose_types: false,
+            closure_style: ClosureStyle::ImplFn,
+            display_target: DisplayTarget::Diagnostics,
+            show_container_bounds,
         }
     }
 }
@@ -277,6 +308,10 @@ impl HirFormatter<'_> {
     pub fn omit_verbose_types(&self) -> bool {
         self.omit_verbose_types
     }
+
+    pub fn show_container_bounds(&self) -> bool {
+        self.show_container_bounds
+    }
 }
 
 #[derive(Clone, Copy)]
@@ -336,6 +371,7 @@ pub struct HirDisplayWrapper<'a, T> {
     omit_verbose_types: bool,
     closure_style: ClosureStyle,
     display_target: DisplayTarget,
+    show_container_bounds: bool,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -365,6 +401,7 @@ impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
             omit_verbose_types: self.omit_verbose_types,
             display_target: self.display_target,
             closure_style: self.closure_style,
+            show_container_bounds: self.show_container_bounds,
         })
     }
 

src/tools/rust-analyzer/crates/hir/Cargo.toml

@@ -27,6 +27,7 @@ cfg.workspace = true
 hir-def.workspace = true
 hir-expand.workspace = true
 hir-ty.workspace = true
+intern.workspace = true
 stdx.workspace = true
 syntax.workspace = true
 tt.workspace = true