From cf78716d04bf8d36a311d9cacb378f24585ab58c Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Thu, 13 Jul 2023 13:35:00 +0200
Subject: [PATCH] self type param infer, avoid ICE

---
 .../src/fn_ctxt/adjust_fulfillment_errors.rs       |  5 ++---
 .../src/infer/error_reporting/need_type_info.rs    |  2 +-
 .../need_type_info/infer-var-for-self-param.rs     |  7 +++++++
 .../need_type_info/infer-var-for-self-param.stderr | 14 ++++++++++++++
 4 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 tests/ui/inference/need_type_info/infer-var-for-self-param.rs
 create mode 100644 tests/ui/inference/need_type_info/infer-var-for-self-param.stderr

diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
index ed9bb4945afc1..0df4ba67b4b1b 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
@@ -2,7 +2,7 @@ use crate::FnCtxt;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
-use rustc_infer::traits::ObligationCauseCode;
+use rustc_infer::{infer::type_variable::TypeVariableOriginKind, traits::ObligationCauseCode};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_span::{self, symbol::kw, Span};
 use rustc_trait_selection::traits;
@@ -254,8 +254,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             type BreakTy = ty::GenericArg<'tcx>;
             fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> {
                 if let Some(origin) = self.0.type_var_origin(ty)
-                    && let rustc_infer::infer::type_variable::TypeVariableOriginKind::TypeParameterDefinition(_, def_id) =
-                        origin.kind
+                    && let TypeVariableOriginKind::TypeParameterDefinition(_, def_id) = origin.kind
                     && let generics = self.0.tcx.generics_of(self.1)
                     && let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id)
                     && let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1)
diff --git a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
index a90a41f5d70a2..5c357f2c65b7e 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
@@ -163,7 +163,7 @@ fn fmt_printer<'a, 'tcx>(infcx: &'a InferCtxt<'tcx>, ns: Namespace) -> FmtPrinte
         let ty_vars = infcx_inner.type_variables();
         let var_origin = ty_vars.var_origin(ty_vid);
         if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) = var_origin.kind
-            && !var_origin.span.from_expansion()
+            && name != kw::SelfUpper && !var_origin.span.from_expansion()
         {
             let generics = infcx.tcx.generics_of(infcx.tcx.parent(def_id));
             let idx = generics.param_def_id_to_index(infcx.tcx, def_id).unwrap();
diff --git a/tests/ui/inference/need_type_info/infer-var-for-self-param.rs b/tests/ui/inference/need_type_info/infer-var-for-self-param.rs
new file mode 100644
index 0000000000000..51ac7943f2490
--- /dev/null
+++ b/tests/ui/inference/need_type_info/infer-var-for-self-param.rs
@@ -0,0 +1,7 @@
+// Regression test for #113610 where we ICEd when trying to print
+// inference variables created by instantiating the self type parameter.
+
+fn main() {
+    let _ = (Default::default(),);
+    //~^ ERROR cannot call associated function on trait
+}
diff --git a/tests/ui/inference/need_type_info/infer-var-for-self-param.stderr b/tests/ui/inference/need_type_info/infer-var-for-self-param.stderr
new file mode 100644
index 0000000000000..fdef4d0dd0920
--- /dev/null
+++ b/tests/ui/inference/need_type_info/infer-var-for-self-param.stderr
@@ -0,0 +1,14 @@
+error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
+  --> $DIR/infer-var-for-self-param.rs:5:14
+   |
+LL |     let _ = (Default::default(),);
+   |              ^^^^^^^^^^^^^^^^ cannot call associated function of trait
+   |
+help: use a fully-qualified path to a specific available implementation (271 found)
+   |
+LL |     let _ = (</* self type */ as Default>::default(),);
+   |              +++++++++++++++++++        +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0790`.