Rejig some top-level rustc_hir_pretty functions.

There are several that are unused and can be removed.

And there are some calls to `to_string`, which can be expressed more
nicely as a `foo_to_string` call, and then `to_string` need not be
`pub`. (This requires adding `pat_to_string`).

Author: nnethercote

Diff for: compiler/rustc_hir_pretty/src/lib.rs

@@ -187,7 +187,7 @@ impl<'a> State<'a> {
     }
 }
 
-pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
+fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
 where
     F: FnOnce(&mut State<'_>),
 {
@@ -196,48 +196,16 @@ where
     printer.s.eof()
 }
 
-pub fn generic_params_to_string(generic_params: &[GenericParam<'_>]) -> String {
-    to_string(NO_ANN, |s| s.print_generic_params(generic_params))
-}
-
-pub fn bounds_to_string<'b>(bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>) -> String {
-    to_string(NO_ANN, |s| s.print_bounds("", bounds))
-}
-
 pub fn ty_to_string(ty: &hir::Ty<'_>) -> String {
     to_string(NO_ANN, |s| s.print_type(ty))
 }
 
-pub fn path_segment_to_string(segment: &hir::PathSegment<'_>) -> String {
-    to_string(NO_ANN, |s| s.print_path_segment(segment))
-}
-
-pub fn path_to_string(segment: &hir::Path<'_>) -> String {
-    to_string(NO_ANN, |s| s.print_path(segment, false))
-}
-
 pub fn qpath_to_string(segment: &hir::QPath<'_>) -> String {
     to_string(NO_ANN, |s| s.print_qpath(segment, false))
 }
 
-pub fn fn_to_string(
-    decl: &hir::FnDecl<'_>,
-    header: hir::FnHeader,
-    name: Option<Symbol>,
-    generics: &hir::Generics<'_>,
-    arg_names: &[Ident],
-    body_id: Option<hir::BodyId>,
-) -> String {
-    to_string(NO_ANN, |s| s.print_fn(decl, header, name, generics, arg_names, body_id))
-}
-
-pub fn enum_def_to_string(
-    enum_definition: &hir::EnumDef<'_>,
-    generics: &hir::Generics<'_>,
-    name: Symbol,
-    span: rustc_span::Span,
-) -> String {
-    to_string(NO_ANN, |s| s.print_enum_def(enum_definition, generics, name, span))
+pub fn pat_to_string(pat: &hir::Pat<'_>) -> String {
+    to_string(NO_ANN, |s| s.print_pat(pat))
 }
 
 impl<'a> State<'a> {

Diff for: compiler/rustc_hir_typeck/src/pat.rs

@@ -1504,9 +1504,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         {
             let has_shorthand_field_name = field_patterns.iter().any(|field| field.is_shorthand);
             if has_shorthand_field_name {
-                let path = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| {
-                    s.print_qpath(qpath, false)
-                });
+                let path = rustc_hir_pretty::qpath_to_string(qpath);
                 let mut err = struct_span_err!(
                     self.tcx.sess,
                     pat.span,
@@ -1688,9 +1686,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 return None;
             }
 
-            let path = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| {
-                s.print_qpath(qpath, false)
-            });
+            let path = rustc_hir_pretty::qpath_to_string(qpath);
             let mut err = struct_span_err!(
                 self.tcx.sess,
                 pat.span,
@@ -1740,9 +1736,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             f
                         }
                     }
-                    Err(_) => rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| {
-                        s.print_pat(field.pat)
-                    }),
+                    Err(_) => rustc_hir_pretty::pat_to_string(field.pat),
                 }
             })
             .collect::<Vec<String>>()

Diff for: src/tools/clippy/clippy_lints/src/matches/match_wild_err_arm.rs

@@ -19,7 +19,7 @@ pub(crate) fn check<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm<'
     if is_type_diagnostic_item(cx, ex_ty, sym::Result) {
         for arm in arms {
             if let PatKind::TupleStruct(ref path, inner, _) = arm.pat.kind {
-                let path_str = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false));
+                let path_str = rustc_hir_pretty::qpath_to_string(path);
                 if path_str == "Err" {
                     let mut matching_wild = inner.iter().any(is_wild);
                     let mut ident_bind_name = kw::Underscore;

Diff for: src/tools/clippy/clippy_lints/src/mut_reference.rs

@@ -49,7 +49,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMutPassed {
                         cx,
                         arguments.iter().collect(),
                         cx.typeck_results().expr_ty(fn_expr),
-                        &rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false)),
+                        &rustc_hir_pretty::qpath_to_string(path),
                         "function",
                     );
                 }