Auto merge of #117171 - fee1-dead-contrib:deny-explicit-effect-params, r=oli-obk

Deny providing explicit effect params

r? `@oli-obk`

cc https://github.com/rust-lang/rust/issues/110395

3 files changed, 30 insertions, 5 deletions

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 1e51449e70c..04a8e2b134a 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -1217,7 +1217,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                     hir_id: this.lower_node_id(node_id),
                                     body: this.lower_const_body(path_expr.span, Some(&path_expr)),
                                 });
-                                return GenericArg::Const(ConstArg { value: ct, span });
+                                return GenericArg::Const(ConstArg {
+                                    value: ct,
+                                    span,
+                                    is_desugared_from_effects: false,
+                                });
                             }
                         }
                     }
@@ -1228,6 +1232,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             ast::GenericArg::Const(ct) => GenericArg::Const(ConstArg {
                 value: self.lower_anon_const(&ct),
                 span: self.lower_span(ct.value.span),
+                is_desugared_from_effects: false,
             }),
         }
     }
@@ -2525,6 +2530,7 @@ impl<'hir> GenericArgsCtor<'hir> {
         self.args.push(hir::GenericArg::Const(hir::ConstArg {
             value: hir::AnonConst { def_id, hir_id, body },
             span,
+            is_desugared_from_effects: true,
         }))
     }
 
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 259af4f565b..17c6352ce24 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -246,6 +246,8 @@ impl<'hir> PathSegment<'hir> {
 pub struct ConstArg {
     pub value: AnonConst,
     pub span: Span,
+    /// Indicates whether this comes from a `~const` desugaring.
+    pub is_desugared_from_effects: bool,
 }
 
 #[derive(Clone, Copy, Debug, HashStable_Generic)]
@@ -400,7 +402,14 @@ impl<'hir> GenericArgs<'hir> {
     /// This function returns the number of type and const generic params.
     /// It should only be used for diagnostics.
     pub fn num_generic_params(&self) -> usize {
-        self.args.iter().filter(|arg| !matches!(arg, GenericArg::Lifetime(_))).count()
+        self.args
+            .iter()
+            .filter(|arg| match arg {
+                GenericArg::Lifetime(_)
+                | GenericArg::Const(ConstArg { is_desugared_from_effects: true, .. }) => false,
+                _ => true,
+            })
+            .count()
     }
 
     /// The span encompassing the text inside the surrounding brackets.
diff --git a/compiler/rustc_hir_analysis/src/astconv/generics.rs b/compiler/rustc_hir_analysis/src/astconv/generics.rs
index 7f0c0b961e4..d29a27eced0 100644
--- a/compiler/rustc_hir_analysis/src/astconv/generics.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/generics.rs
@@ -429,6 +429,14 @@ pub(crate) fn check_generic_arg_count(
         .filter(|param| matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: true, .. }))
         .count();
     let named_type_param_count = param_counts.types - has_self as usize - synth_type_param_count;
+    let synth_const_param_count = gen_params
+        .params
+        .iter()
+        .filter(|param| {
+            matches!(param.kind, ty::GenericParamDefKind::Const { is_host_effect: true, .. })
+        })
+        .count();
+    let named_const_param_count = param_counts.consts - synth_const_param_count;
     let infer_lifetimes =
         (gen_pos != GenericArgPosition::Type || infer_args) && !gen_args.has_lifetime_params();
 
@@ -573,11 +581,13 @@ pub(crate) fn check_generic_arg_count(
         debug!(?expected_min);
         debug!(arg_counts.lifetimes=?gen_args.num_lifetime_params());
 
+        let provided = gen_args.num_generic_params();
+
         check_types_and_consts(
             expected_min,
-            param_counts.consts + named_type_param_count,
-            param_counts.consts + named_type_param_count + synth_type_param_count,
-            gen_args.num_generic_params(),
+            named_const_param_count + named_type_param_count,
+            named_const_param_count + named_type_param_count + synth_type_param_count,
+            provided,
             param_counts.lifetimes + has_self as usize,
             gen_args.num_lifetime_params(),
         )