Revert "Don't print host effect param in pretty path_generic_args"

This reverts commit f1bf874fb13703d706fc8184407c6df12555d8e9.

3 files changed, 33 insertions, 26 deletions

diff --git a/compiler/rustc_middle/src/ty/generics.rs b/compiler/rustc_middle/src/ty/generics.rs
index f0e63dfddda..4a4a9db1bb3 100644
--- a/compiler/rustc_middle/src/ty/generics.rs
+++ b/compiler/rustc_middle/src/ty/generics.rs
@@ -320,11 +320,9 @@ impl<'tcx> Generics {
         &'tcx self,
         tcx: TyCtxt<'tcx>,
         args: &'tcx [ty::GenericArg<'tcx>],
-    ) -> (&'tcx [ty::GenericArg<'tcx>], &'tcx [ty::GenericParamDef]) {
-        let mut own_args = self.parent_count..self.count();
-        let mut own_params = 0..self.params.len();
+    ) -> &'tcx [ty::GenericArg<'tcx>] {
+        let mut own_params = self.parent_count..self.count();
         if self.has_self && self.parent.is_none() {
-            own_args.start = 1;
             own_params.start = 1;
         }
 
@@ -334,7 +332,7 @@ impl<'tcx> Generics {
         // of semantic equivalence. While not ideal, that's
         // good enough for now as this should only be used
         // for diagnostics anyways.
-        let num_default_params = self
+        own_params.end -= self
             .params
             .iter()
             .rev()
@@ -346,10 +344,8 @@ impl<'tcx> Generics {
                 || matches!(param.kind, GenericParamDefKind::Const { is_host_effect: true, .. })
             })
             .count();
-        own_params.end -= num_default_params;
-        own_args.end -= num_default_params;
 
-        (&args[own_args], &self.params[own_params])
+        &args[own_params]
     }
 
     /// Returns the args corresponding to the generic parameters of this item, excluding `Self`.
diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs
index 948246c64e2..5e09154789a 100644
--- a/compiler/rustc_middle/src/ty/print/mod.rs
+++ b/compiler/rustc_middle/src/ty/print/mod.rs
@@ -83,7 +83,6 @@ pub trait Printer<'tcx>: Sized {
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
-        params: &[ty::GenericParamDef],
     ) -> Result<(), PrintError>;
 
     // Defaults (should not be overridden):
@@ -142,12 +141,10 @@ pub trait Printer<'tcx>: Sized {
                         // on top of the same path, but without its own generics.
                         _ => {
                             if !generics.params.is_empty() && args.len() >= generics.count() {
-                                let (args, params) =
-                                    generics.own_args_no_defaults(self.tcx(), args);
+                                let args = generics.own_args_no_defaults(self.tcx(), args);
                                 return self.path_generic_args(
                                     |cx| cx.print_def_path(def_id, parent_args),
                                     args,
-                                    params,
                                 );
                             }
                         }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index fd53111001b..f3ff9b0ba4b 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -19,6 +19,7 @@ use rustc_hir::LangItem;
 use rustc_session::config::TrimmedDefPaths;
 use rustc_session::cstore::{ExternCrate, ExternCrateSource};
 use rustc_session::Limit;
+use rustc_span::sym;
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::FileNameDisplayPreference;
 use rustc_target::abi::Size;
@@ -966,7 +967,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 define_scoped_cx!(cx);
                 // Get the (single) generic ty (the args) of this FnOnce trait ref.
                 let generics = tcx.generics_of(trait_ref.def_id);
-                let (own_args, _) = generics.own_args_no_defaults(tcx, trait_ref.args);
+                let own_args = generics.own_args_no_defaults(tcx, trait_ref.args);
 
                 match (entry.return_ty, own_args[0].expect_ty()) {
                     // We can only print `impl Fn() -> ()` if we have a tuple of args and we recorded
@@ -1032,7 +1033,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 p!(print(trait_ref.print_only_trait_name()));
 
                 let generics = tcx.generics_of(trait_ref.def_id);
-                let (own_args, _) = generics.own_args_no_defaults(tcx, trait_ref.args);
+                let own_args = generics.own_args_no_defaults(tcx, trait_ref.args);
 
                 if !own_args.is_empty() || !assoc_items.is_empty() {
                     let mut first = true;
@@ -1184,7 +1185,6 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 )
             },
             &alias_ty.args[1..],
-            &self.tcx().generics_of(alias_ty.def_id).params,
         )
     }
 
@@ -1233,7 +1233,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     let dummy_cx = Ty::new_fresh(cx.tcx(), 0);
                     let principal = principal.with_self_ty(cx.tcx(), dummy_cx);
 
-                    let (args, _) = cx
+                    let args = cx
                         .tcx()
                         .generics_of(principal.def_id)
                         .own_args_no_defaults(cx.tcx(), principal.args);
@@ -2031,26 +2031,40 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
-        params: &[ty::GenericParamDef],
     ) -> Result<(), PrintError> {
         print_prefix(self)?;
 
         let tcx = self.tcx;
-        let verbose = tcx.sess.verbose();
-        let mut args = args
-            .iter()
-            .copied()
-            .zip(params)
+
+        let args = args.iter().copied();
+
+        let args: Vec<_> = if !tcx.sess.verbose() {
+            // skip host param as those are printed as `~const`
+            args.filter(|arg| match arg.unpack() {
+                // FIXME(effects) there should be a better way than just matching the name
+                GenericArgKind::Const(c)
+                    if tcx.features().effects
+                        && matches!(
+                            c.kind(),
+                            ty::ConstKind::Param(ty::ParamConst { name: sym::host, .. })
+                        ) =>
+                {
+                    false
+                }
+                _ => true,
+            })
+            .collect()
+        } else {
             // If -Zverbose is passed, we should print the host parameter instead
             // of eating it.
-            .filter(|(_, param)| verbose || !param.is_host_effect())
-            .peekable();
+            args.collect()
+        };
 
-        if args.peek().is_some() {
+        if !args.is_empty() {
             if self.in_value {
                 write!(self, "::")?;
             }
-            self.generic_delimiters(|cx| cx.comma_sep(args.map(|(arg, _)| arg)))
+            self.generic_delimiters(|cx| cx.comma_sep(args.into_iter()))
         } else {
             Ok(())
         }