Rollup merge of #136646 - oli-obk:pattern-types-ast, r=BoxyUwU

Add a TyPat in the AST to reuse the generic arg lowering logic

This simplifies ast lowering significantly with little cost to the pattern types parser.

Also fixes any problems we've had with generic args (well, pushes any problems onto the `generic_const_exprs` feature gate)

follow-up to https://github.com/rust-lang/rust/pull/136284#discussion_r1939292367

r? ``@BoxyUwU``

3 files changed, 66 insertions, 39 deletions

diff --git a/src/tools/rustfmt/src/patterns.rs b/src/tools/rustfmt/src/patterns.rs
index 1d88726d945..bafed41e39f 100644
--- a/src/tools/rustfmt/src/patterns.rs
+++ b/src/tools/rustfmt/src/patterns.rs
@@ -75,12 +75,12 @@ fn is_short_pattern_inner(context: &RewriteContext<'_>, pat: &ast::Pat) -> bool
     }
 }
 
-pub(crate) struct RangeOperand<'a> {
-    operand: &'a Option<ptr::P<ast::Expr>>,
-    pub(crate) span: Span,
+pub(crate) struct RangeOperand<'a, T> {
+    pub operand: &'a Option<ptr::P<T>>,
+    pub span: Span,
 }
 
-impl<'a> Rewrite for RangeOperand<'a> {
+impl<'a, T: Rewrite> Rewrite for RangeOperand<'a, T> {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
         self.rewrite_result(context, shape).ok()
     }
@@ -259,40 +259,7 @@ impl Rewrite for Pat {
             }
             PatKind::Never => Err(RewriteError::Unknown),
             PatKind::Range(ref lhs, ref rhs, ref end_kind) => {
-                let infix = match end_kind.node {
-                    RangeEnd::Included(RangeSyntax::DotDotDot) => "...",
-                    RangeEnd::Included(RangeSyntax::DotDotEq) => "..=",
-                    RangeEnd::Excluded => "..",
-                };
-                let infix = if context.config.spaces_around_ranges() {
-                    let lhs_spacing = match lhs {
-                        None => "",
-                        Some(_) => " ",
-                    };
-                    let rhs_spacing = match rhs {
-                        None => "",
-                        Some(_) => " ",
-                    };
-                    format!("{lhs_spacing}{infix}{rhs_spacing}")
-                } else {
-                    infix.to_owned()
-                };
-                let lspan = self.span.with_hi(end_kind.span.lo());
-                let rspan = self.span.with_lo(end_kind.span.hi());
-                rewrite_pair(
-                    &RangeOperand {
-                        operand: lhs,
-                        span: lspan,
-                    },
-                    &RangeOperand {
-                        operand: rhs,
-                        span: rspan,
-                    },
-                    PairParts::infix(&infix),
-                    context,
-                    shape,
-                    SeparatorPlace::Front,
-                )
+                rewrite_range_pat(context, shape, lhs, rhs, end_kind, self.span)
             }
             PatKind::Ref(ref pat, mutability) => {
                 let prefix = format!("&{}", format_mutability(mutability));
@@ -359,6 +326,50 @@ impl Rewrite for Pat {
     }
 }
 
+pub fn rewrite_range_pat<T: Rewrite>(
+    context: &RewriteContext<'_>,
+    shape: Shape,
+    lhs: &Option<ptr::P<T>>,
+    rhs: &Option<ptr::P<T>>,
+    end_kind: &rustc_span::source_map::Spanned<RangeEnd>,
+    span: Span,
+) -> RewriteResult {
+    let infix = match end_kind.node {
+        RangeEnd::Included(RangeSyntax::DotDotDot) => "...",
+        RangeEnd::Included(RangeSyntax::DotDotEq) => "..=",
+        RangeEnd::Excluded => "..",
+    };
+    let infix = if context.config.spaces_around_ranges() {
+        let lhs_spacing = match lhs {
+            None => "",
+            Some(_) => " ",
+        };
+        let rhs_spacing = match rhs {
+            None => "",
+            Some(_) => " ",
+        };
+        format!("{lhs_spacing}{infix}{rhs_spacing}")
+    } else {
+        infix.to_owned()
+    };
+    let lspan = span.with_hi(end_kind.span.lo());
+    let rspan = span.with_lo(end_kind.span.hi());
+    rewrite_pair(
+        &RangeOperand {
+            operand: lhs,
+            span: lspan,
+        },
+        &RangeOperand {
+            operand: rhs,
+            span: rspan,
+        },
+        PairParts::infix(&infix),
+        context,
+        shape,
+        SeparatorPlace::Front,
+    )
+}
+
 fn rewrite_struct_pat(
     qself: &Option<ptr::P<ast::QSelf>>,
     path: &ast::Path,
diff --git a/src/tools/rustfmt/src/spanned.rs b/src/tools/rustfmt/src/spanned.rs
index 6b3e40b9115..e93eb53cd87 100644
--- a/src/tools/rustfmt/src/spanned.rs
+++ b/src/tools/rustfmt/src/spanned.rs
@@ -211,7 +211,7 @@ impl Spanned for ast::PreciseCapturingArg {
     }
 }
 
-impl<'a> Spanned for RangeOperand<'a> {
+impl<'a, T> Spanned for RangeOperand<'a, T> {
     fn span(&self) -> Span {
         self.span
     }
diff --git a/src/tools/rustfmt/src/types.rs b/src/tools/rustfmt/src/types.rs
index f8b713117f4..0009490e86f 100644
--- a/src/tools/rustfmt/src/types.rs
+++ b/src/tools/rustfmt/src/types.rs
@@ -18,6 +18,7 @@ use crate::lists::{
 use crate::macros::{MacroPosition, rewrite_macro};
 use crate::overflow;
 use crate::pairs::{PairParts, rewrite_pair};
+use crate::patterns::rewrite_range_pat;
 use crate::rewrite::{Rewrite, RewriteContext, RewriteError, RewriteErrorExt, RewriteResult};
 use crate::shape::Shape;
 use crate::source_map::SpanUtils;
@@ -1045,6 +1046,21 @@ impl Rewrite for ast::Ty {
     }
 }
 
+impl Rewrite for ast::TyPat {
+    fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
+        self.rewrite_result(context, shape).ok()
+    }
+
+    fn rewrite_result(&self, context: &RewriteContext<'_>, shape: Shape) -> RewriteResult {
+        match self.kind {
+            ast::TyPatKind::Range(ref lhs, ref rhs, ref end_kind) => {
+                rewrite_range_pat(context, shape, lhs, rhs, end_kind, self.span)
+            }
+            ast::TyPatKind::Err(_) => Err(RewriteError::Unknown),
+        }
+    }
+}
+
 fn rewrite_bare_fn(
     bare_fn: &ast::BareFnTy,
     span: Span,