diff --git a/compiler/rustc_hir_typeck/src/closure.rs b/compiler/rustc_hir_typeck/src/closure.rs
index 7037f1fde73b4..40b12fd84f4cd 100644
--- a/compiler/rustc_hir_typeck/src/closure.rs
+++ b/compiler/rustc_hir_typeck/src/closure.rs
@@ -100,11 +100,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
                     // Create a type variable (for now) to represent the closure kind.
                     // It will be unified during the upvar inference phase (`upvar.rs`)
-                    None => self.next_ty_var(TypeVariableOrigin {
-                        // FIXME(eddyb) distinguish closure kind inference variables from the rest.
-                        param_def_id: None,
-                        span: expr_span,
-                    }),
+                    None => {
+                        self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: expr_span })
+                    }
                 };
 
                 let closure_args = ty::ClosureArgs::new(
@@ -217,11 +215,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: expr_span });
                 let interior =
                     self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: expr_span });
-                let closure_kind_ty = self.next_ty_var(TypeVariableOrigin {
-                    // FIXME(eddyb) distinguish closure kind inference variables from the rest.
-                    param_def_id: None,
-                    span: expr_span,
-                });
+                let closure_kind_ty =
+                    self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: expr_span });
                 let coroutine_captures_by_ref_ty =
                     self.next_ty_var(TypeVariableOrigin { param_def_id: None, span: expr_span });
                 let closure_args = ty::CoroutineClosureArgs::new(
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs
index a38bf5b2b7938..b63cb86117ff4 100644
--- a/compiler/rustc_hir_typeck/src/pat.rs
+++ b/compiler/rustc_hir_typeck/src/pat.rs
@@ -1340,13 +1340,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
         let max_len = cmp::max(expected_len, elements.len());
 
-        let element_tys_iter = (0..max_len).map(|_| {
-            self.next_ty_var(
-                // FIXME: `MiscVariable` for now -- obtaining the span and name information
-                // from all tuple elements isn't trivial.
-                TypeVariableOrigin { param_def_id: None, span },
-            )
-        });
+        let element_tys_iter =
+            (0..max_len).map(|_| self.next_ty_var(TypeVariableOrigin { param_def_id: None, span }));
         let element_tys = tcx.mk_type_list_from_iter(element_tys_iter);
         let pat_ty = Ty::new_tup(tcx, element_tys);
         if let Some(err) = self.demand_eqtype_pat_diag(span, expected, pat_ty, pat_info.top_info) {
diff --git a/compiler/rustc_infer/src/infer/opaque_types/mod.rs b/compiler/rustc_infer/src/infer/opaque_types/mod.rs
index 6f095ad45d95b..ae3bd132100a1 100644
--- a/compiler/rustc_infer/src/infer/opaque_types/mod.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types/mod.rs
@@ -69,9 +69,6 @@ impl<'tcx> InferCtxt<'tcx> {
                     let span = if span.contains(def_span) { def_span } else { span };
                     let code = traits::ObligationCauseCode::OpaqueReturnType(None);
                     let cause = ObligationCause::new(span, body_id, code);
-                    // FIXME(compiler-errors): We probably should add a new TypeVariableOriginKind
-                    // for opaque types, and then use that kind to fix the spans for type errors
-                    // that we see later on.
                     let ty_var = self.next_ty_var(TypeVariableOrigin { param_def_id: None, span });
                     obligations.extend(
                         self.handle_opaque_type(ty, ty_var, &cause, param_env).unwrap().obligations,
diff --git a/compiler/rustc_infer/src/infer/type_variable.rs b/compiler/rustc_infer/src/infer/type_variable.rs
index e6cc950ab25b0..96afa257ebbad 100644
--- a/compiler/rustc_infer/src/infer/type_variable.rs
+++ b/compiler/rustc_infer/src/infer/type_variable.rs
@@ -37,7 +37,9 @@ pub struct TypeVariableTable<'a, 'tcx> {
 #[derive(Copy, Clone, Debug)]
 pub struct TypeVariableOrigin {
     pub span: Span,
-    // `DefId` of the type parameter this was instantiated for, if any.
+    /// `DefId` of the type parameter this was instantiated for, if any.
+    ///
+    /// This should only be used for diagnostics.
     pub param_def_id: Option<DefId>,
 }
 
diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs
index 5280acd72ce7d..105be21f27279 100644
--- a/compiler/rustc_middle/src/infer/unify_key.rs
+++ b/compiler/rustc_middle/src/infer/unify_key.rs
@@ -106,7 +106,9 @@ impl ToType for ty::FloatVarValue {
 #[derive(Copy, Clone, Debug)]
 pub struct ConstVariableOrigin {
     pub span: Span,
-    // `DefId` of the const parameter this was instantiated for, if any.
+    /// `DefId` of the const parameter this was instantiated for, if any.
+    ///
+    /// This should only be used for diagnostics.
     pub param_def_id: Option<DefId>,
 }