Rollup merge of #122768 - oli-obk:why_is_E0699_so_bad, r=WaffleLapkin

Use the more informative generic type inference failure error on method calls on raw pointers

5 files changed, 30 insertions, 29 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0699.md b/compiler/rustc_error_codes/src/error_codes/E0699.md
index 454d2507e5e..1094ebf4b8f 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0699.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0699.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 A method was called on a raw pointer whose inner type wasn't completely known.
 
 Erroneous code example:
 
-```compile_fail,edition2018,E0699
+```compile_fail,edition2018
 # #![deny(warnings)]
 # fn main() {
 let foo = &1;
diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index da688e385aa..f4a33a05c1b 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -441,7 +441,7 @@ E0695: 0695,
 E0696: 0696,
 E0697: 0697,
 E0698: 0698,
-E0699: 0699,
+E0699: 0699, // REMOVED: merged into generic inference var error
 E0700: 0700,
 E0701: 0701,
 E0703: 0703,
diff --git a/compiler/rustc_hir_typeck/messages.ftl b/compiler/rustc_hir_typeck/messages.ftl
index 1d51101c940..18d9d739dd6 100644
--- a/compiler/rustc_hir_typeck/messages.ftl
+++ b/compiler/rustc_hir_typeck/messages.ftl
@@ -93,9 +93,6 @@ hir_typeck_lossy_provenance_ptr2int =
     .suggestion = use `.addr()` to obtain the address of a pointer
     .help = if you can't comply with strict provenance and need to expose the pointer provenance you can use `.expose_provenance()` instead
 
-hir_typeck_method_call_on_unknown_raw_pointee =
-    cannot call a method on a raw pointer with an unknown pointee type
-
 hir_typeck_missing_parentheses_in_range = can't call method `{$method_name}` on type `{$ty_str}`
 
 hir_typeck_no_associated_item = no {$item_kind} named `{$item_name}` found for {$ty_prefix} `{$ty_str}`{$trait_missing_method ->
diff --git a/compiler/rustc_hir_typeck/src/errors.rs b/compiler/rustc_hir_typeck/src/errors.rs
index f9b2ec69730..d399730bf3d 100644
--- a/compiler/rustc_hir_typeck/src/errors.rs
+++ b/compiler/rustc_hir_typeck/src/errors.rs
@@ -77,13 +77,6 @@ pub struct StructExprNonExhaustive {
 }
 
 #[derive(Diagnostic)]
-#[diag(hir_typeck_method_call_on_unknown_raw_pointee, code = E0699)]
-pub struct MethodCallOnUnknownRawPointee {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(hir_typeck_functional_record_update_on_non_struct, code = E0436)]
 pub struct FunctionalRecordUpdateOnNonStruct {
     #[primary_span]
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 4e63600dbdf..28e17e1de36 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -3,7 +3,6 @@ use super::CandidateSource;
 use super::MethodError;
 use super::NoMatchData;
 
-use crate::errors::MethodCallOnUnknownRawPointee;
 use crate::FnCtxt;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -430,21 +429,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if is_suggestion.0 {
                 // Ambiguity was encountered during a suggestion. Just keep going.
                 debug!("ProbeContext: encountered ambiguity in suggestion");
-            } else if bad_ty.reached_raw_pointer && !self.tcx.features().arbitrary_self_types {
+            } else if bad_ty.reached_raw_pointer
+                && !self.tcx.features().arbitrary_self_types
+                && !self.tcx.sess.at_least_rust_2018()
+            {
                 // this case used to be allowed by the compiler,
                 // so we do a future-compat lint here for the 2015 edition
                 // (see https://github.com/rust-lang/rust/issues/46906)
-                if self.tcx.sess.at_least_rust_2018() {
-                    self.dcx().emit_err(MethodCallOnUnknownRawPointee { span });
-                } else {
-                    self.tcx.node_span_lint(
-                        lint::builtin::TYVAR_BEHIND_RAW_POINTER,
-                        scope_expr_id,
-                        span,
-                        "type annotations needed",
-                        |_| {},
-                    );
-                }
+                self.tcx.node_span_lint(
+                    lint::builtin::TYVAR_BEHIND_RAW_POINTER,
+                    scope_expr_id,
+                    span,
+                    "type annotations needed",
+                    |_| {},
+                );
             } else {
                 // Ended up encountering a type variable when doing autoderef,
                 // but it may not be a type variable after processing obligations
@@ -455,10 +453,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .unwrap_or_else(|_| span_bug!(span, "instantiating {:?} failed?", ty));
                 let ty = self.resolve_vars_if_possible(ty.value);
                 let guar = match *ty.kind() {
-                    ty::Infer(ty::TyVar(_)) => self
-                        .err_ctxt()
-                        .emit_inference_failure_err(self.body_id, span, ty.into(), E0282, true)
-                        .emit(),
+                    ty::Infer(ty::TyVar(_)) => {
+                        let raw_ptr_call =
+                            bad_ty.reached_raw_pointer && !self.tcx.features().arbitrary_self_types;
+                        let mut err = self.err_ctxt().emit_inference_failure_err(
+                            self.body_id,
+                            span,
+                            ty.into(),
+                            E0282,
+                            !raw_ptr_call,
+                        );
+                        if raw_ptr_call {
+                            err.span_label(span, "cannot call a method on a raw pointer with an unknown pointee type");
+                        }
+                        err.emit()
+                    }
                     ty::Error(guar) => guar,
                     _ => bug!("unexpected bad final type in method autoderef"),
                 };