diff --git a/src/implementation/intermediate_public_item.rs b/src/implementation/intermediate_public_item.rs
index 9e2b14ab..6dcd4be9 100644
--- a/src/implementation/intermediate_public_item.rs
+++ b/src/implementation/intermediate_public_item.rs
@@ -310,8 +310,20 @@ impl Display for D<&FnDecl> {
 
 impl Display for D<&Vec<GenericParamDef>> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        if !self.0.is_empty() {
-            write!(f, "<{}>", Joiner(self.0, ", ", D))?;
+        let params_without_synthetics: Vec<_> = self
+            .0
+            .iter()
+            // For now we use a heuristic that I think is pretty solid.
+            // Once https://github.com/rust-lang/rust/pull/94150 is fixed
+            // we should replace this with a solid and simple check for `.synthetic`
+            .filter(|p| !p.name.starts_with("impl "))
+            .collect();
+        if !&params_without_synthetics.is_empty() {
+            write!(
+                f,
+                "<{}>",
+                Joiner(&params_without_synthetics, ", ", |x| D(*x))
+            )?;
         }
 
         Ok(())
@@ -416,7 +428,7 @@ impl Display for D<&GenericArgs> {
                 if !inputs.is_empty() {
                     write!(
                         f,
-                        "Fn<{}>{}",
+                        "({}){}",
                         Joiner(inputs, ", ", D),
                         Optional(" -> ", output.as_ref().map(D))
                     )?;
diff --git a/tests/rustdoc_json/bat-v0.19.0-expected.txt b/tests/rustdoc_json/bat-v0.19.0-expected.txt
index 2b0f28c0..4490c1fb 100644
--- a/tests/rustdoc_json/bat-v0.19.0-expected.txt
+++ b/tests/rustdoc_json/bat-v0.19.0-expected.txt
@@ -39,12 +39,12 @@ pub enum variant bat::style::StyleComponent::Rule
 pub enum variant bat::style::StyleComponent::Snip
 pub fn bat::Input::from(input: input::Input<'a>) -> Self
 pub fn bat::Input::from_bytes(bytes: &'a [u8]) -> Self
-pub fn bat::Input::from_file<impl AsRef<Path>: AsRef<Path>>(path: impl AsRef<Path>) -> Self
+pub fn bat::Input::from_file(path: impl AsRef<Path>) -> Self
 pub fn bat::Input::from_reader<R: Read, 'a>(reader: R) -> Self
 pub fn bat::Input::from_stdin() -> Self
-pub fn bat::Input::kind<impl Into<String>: Into<String>>(self, kind: impl Into<String>) -> Self
-pub fn bat::Input::name<impl AsRef<Path>: AsRef<Path>>(self, name: impl AsRef<Path>) -> Self
-pub fn bat::Input::title<impl Into<String>: Into<String>>(self, title: impl Into<String>) -> Self
+pub fn bat::Input::kind(self, kind: impl Into<String>) -> Self
+pub fn bat::Input::name(self, name: impl AsRef<Path>) -> Self
+pub fn bat::Input::title(self, title: impl Into<String>) -> Self
 pub fn bat::MappingTarget::clone(&self) -> MappingTarget<'a>
 pub fn bat::MappingTarget::eq(&self, other: &MappingTarget<'a>) -> bool
 pub fn bat::MappingTarget::fmt(&self, f: &mut $crate::fmt::Formatter<'_>) -> $crate::fmt::Result
@@ -60,12 +60,12 @@ pub fn bat::PrettyPrinter::header(&mut self, yes: bool) -> &mut Self
 pub fn bat::PrettyPrinter::highlight(&mut self, line: usize) -> &mut Self
 pub fn bat::PrettyPrinter::highlight_range(&mut self, from: usize, to: usize) -> &mut Self
 pub fn bat::PrettyPrinter::input(&mut self, input: Input<'a>) -> &mut Self
-pub fn bat::PrettyPrinter::input_file<impl AsRef<Path>: AsRef<Path>>(&mut self, path: impl AsRef<Path>) -> &mut Self
+pub fn bat::PrettyPrinter::input_file(&mut self, path: impl AsRef<Path>) -> &mut Self
 pub fn bat::PrettyPrinter::input_files<I, P>(&mut self, paths: I) -> &mut Self where I: IntoIterator<Item = P>, P: AsRef<Path>
 pub fn bat::PrettyPrinter::input_from_bytes(&mut self, content: &'a [u8]) -> &mut Self
 pub fn bat::PrettyPrinter::input_from_reader<R: Read, 'a>(&mut self, reader: R) -> &mut Self
 pub fn bat::PrettyPrinter::input_stdin(&mut self) -> &mut Self
-pub fn bat::PrettyPrinter::inputs<impl IntoIterator<Item = Input<'a>>: IntoIterator<Item = Input<'a>>>(&mut self, inputs: impl IntoIterator<Item = Input<'a>>) -> &mut Self
+pub fn bat::PrettyPrinter::inputs(&mut self, inputs: impl IntoIterator<Item = Input<'a>>) -> &mut Self
 pub fn bat::PrettyPrinter::language(&mut self, language: &'a str) -> &mut Self
 pub fn bat::PrettyPrinter::line_numbers(&mut self, yes: bool) -> &mut Self
 pub fn bat::PrettyPrinter::line_ranges(&mut self, ranges: LineRanges) -> &mut Self
@@ -79,7 +79,7 @@ pub fn bat::PrettyPrinter::syntax_mapping(&mut self, mapping: SyntaxMapping<'a>)
 pub fn bat::PrettyPrinter::syntaxes(&self) -> impl Iterator<Item = &SyntaxReference>
 pub fn bat::PrettyPrinter::tab_width(&mut self, tab_width: Option<usize>) -> &mut Self
 pub fn bat::PrettyPrinter::term_width(&mut self, width: usize) -> &mut Self
-pub fn bat::PrettyPrinter::theme<impl AsRef<str>: AsRef<str>>(&mut self, theme: impl AsRef<str>) -> &mut Self
+pub fn bat::PrettyPrinter::theme(&mut self, theme: impl AsRef<str>) -> &mut Self
 pub fn bat::PrettyPrinter::themes(&self) -> impl Iterator<Item = &str>
 pub fn bat::PrettyPrinter::true_color(&mut self, yes: bool) -> &mut Self
 pub fn bat::PrettyPrinter::use_italics(&mut self, yes: bool) -> &mut Self
@@ -102,10 +102,10 @@ pub fn bat::assets::HighlightingAssets::default_theme() -> &'static str
 pub fn bat::assets::HighlightingAssets::fmt(&self, f: &mut $crate::fmt::Formatter<'_>) -> $crate::fmt::Result
 pub fn bat::assets::HighlightingAssets::from_binary() -> Self
 pub fn bat::assets::HighlightingAssets::from_cache(cache_path: &Path) -> Result<Self>
-pub fn bat::assets::HighlightingAssets::get_syntax_for_path<impl AsRef<Path>: AsRef<Path>>(&self, path: impl AsRef<Path>, mapping: &SyntaxMapping<'_>) -> Result<SyntaxReferenceInSet<'_>>
+pub fn bat::assets::HighlightingAssets::get_syntax_for_path(&self, path: impl AsRef<Path>, mapping: &SyntaxMapping<'_>) -> Result<SyntaxReferenceInSet<'_>>
 pub fn bat::assets::HighlightingAssets::get_syntaxes(&self) -> Result<&[SyntaxReference]>
 pub fn bat::assets::HighlightingAssets::set_fallback_theme(&mut self, theme: &'static str)
-pub fn bat::assets::HighlightingAssets::syntax_for_file_name<impl AsRef<Path>: AsRef<Path>>(&self, file_name: impl AsRef<Path>, mapping: &SyntaxMapping<'_>) -> Option<&SyntaxReference>
+pub fn bat::assets::HighlightingAssets::syntax_for_file_name(&self, file_name: impl AsRef<Path>, mapping: &SyntaxMapping<'_>) -> Option<&SyntaxReference>
 pub fn bat::assets::HighlightingAssets::syntaxes(&self) -> &[SyntaxReference]
 pub fn bat::assets::HighlightingAssets::themes(&self) -> impl Iterator<Item = &str>
 pub fn bat::assets::SyntaxReferenceInSet::fmt(&self, f: &mut $crate::fmt::Formatter<'_>) -> $crate::fmt::Result
@@ -129,7 +129,7 @@ pub fn bat::config::VisibleLines::fmt(&self, f: &mut $crate::fmt::Formatter<'_>)
 pub fn bat::config::get_pager_executable(config_pager: Option<&str>) -> Option<String>
 pub fn bat::controller::Controller::new<'a>(config: &'a Config<'_>, assets: &'a HighlightingAssets) -> Controller<'a>
 pub fn bat::controller::Controller::run(&self, inputs: Vec<Input<'_>>) -> Result<bool>
-pub fn bat::controller::Controller::run_with_error_handler<impl Fn(&Error, &mut dyn Write): FnFn<&Error, &mut Write>>(&self, inputs: Vec<Input<'_>>, handle_error: impl FnFn<&Error, &mut Write>) -> Result<bool>
+pub fn bat::controller::Controller::run_with_error_handler(&self, inputs: Vec<Input<'_>>, handle_error: impl Fn(&Error, &mut Write)) -> Result<bool>
 pub fn bat::error::Error::fmt(&self, __formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
 pub fn bat::error::Error::fmt(&self, f: &mut $crate::fmt::Formatter<'_>) -> $crate::fmt::Result
 pub fn bat::error::Error::from(s: &'static str) -> Self
@@ -146,12 +146,12 @@ pub fn bat::input::Input::description_mut(&mut self) -> &mut InputDescription
 pub fn bat::input::Input::from(_: Input<'a>) -> Self
 pub fn bat::input::Input::from_reader(reader: Box<Read + 'a>) -> Self
 pub fn bat::input::Input::is_stdin(&self) -> bool
-pub fn bat::input::Input::ordinary_file<impl AsRef<Path>: AsRef<Path>>(path: impl AsRef<Path>) -> Self
+pub fn bat::input::Input::ordinary_file(path: impl AsRef<Path>) -> Self
 pub fn bat::input::Input::stdin() -> Self
-pub fn bat::input::Input::with_name<impl AsRef<Path>: AsRef<Path>>(self, provided_name: Option<impl AsRef<Path>>) -> Self
+pub fn bat::input::Input::with_name(self, provided_name: Option<impl AsRef<Path>>) -> Self
 pub fn bat::input::InputDescription::clone(&self) -> InputDescription
 pub fn bat::input::InputDescription::kind(&self) -> Option<&String>
-pub fn bat::input::InputDescription::new<impl Into<String>: Into<String>>(name: impl Into<String>) -> Self
+pub fn bat::input::InputDescription::new(name: impl Into<String>) -> Self
 pub fn bat::input::InputDescription::set_kind(&mut self, kind: Option<String>)
 pub fn bat::input::InputDescription::set_summary(&mut self, summary: Option<String>)
 pub fn bat::input::InputDescription::set_title(&mut self, title: Option<String>)
diff --git a/tests/rustdoc_json/syntect-v4.6.0-expected.txt b/tests/rustdoc_json/syntect-v4.6.0-expected.txt
index e0396fbb..7eb91f59 100644
--- a/tests/rustdoc_json/syntect-v4.6.0-expected.txt
+++ b/tests/rustdoc_json/syntect-v4.6.0-expected.txt
@@ -330,7 +330,7 @@ pub fn syntect::parsing::ScopeRepository::build(&mut self, s: &str) -> Result<Sc
 pub fn syntect::parsing::ScopeRepository::fmt(&self, f: &mut $crate::fmt::Formatter<'_>) -> $crate::fmt::Result
 pub fn syntect::parsing::ScopeRepository::to_string(&self, scope: Scope) -> String
 pub fn syntect::parsing::ScopeStack::apply(&mut self, op: &ScopeStackOp)
-pub fn syntect::parsing::ScopeStack::apply_with_hook<F>(&mut self, op: &ScopeStackOp, hook: F) where F: FnMutFn<BasicScopeStackOp, &[Scope]>
+pub fn syntect::parsing::ScopeStack::apply_with_hook<F>(&mut self, op: &ScopeStackOp, hook: F) where F: FnMut(BasicScopeStackOp, &[Scope])
 pub fn syntect::parsing::ScopeStack::as_slice(&self) -> &[Scope]
 pub fn syntect::parsing::ScopeStack::bottom_n(&self, n: usize) -> &[Scope]
 pub fn syntect::parsing::ScopeStack::clone(&self) -> ScopeStack