From 5021dcd7998ff721a247369bca601bd001a1a3e0 Mon Sep 17 00:00:00 2001
From: nils <48135649+Nilstrieb@users.noreply.github.com>
Date: Wed, 20 Jul 2022 18:32:58 +0200
Subject: [PATCH] Display raw pointer as `*{mut,const} T` instead of `*-ptr` in
 errors

The `*-ptr` is rather confusing, and we have the full information for
properly displaying the information.
---
 compiler/rustc_middle/src/ty/error.rs           | 15 ++++++++++++++-
 src/test/ui/asm/type-check-1.stderr             |  4 ++--
 src/test/ui/dst/dst-bad-coercions.stderr        |  8 ++++----
 src/test/ui/mismatched_types/issue-19109.stderr |  2 +-
 4 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index ac89bec702efd..da564c66a70e1 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -276,10 +276,23 @@ impl<'tcx> Ty<'tcx> {
             }
             ty::Slice(ty) if ty.is_simple_ty() => format!("slice `{}`", self).into(),
             ty::Slice(_) => "slice".into(),
-            ty::RawPtr(_) => "*-ptr".into(),
+            ty::RawPtr(tymut) => {
+                let tymut_string = match tymut.mutbl {
+                    hir::Mutability::Mut => tymut.to_string(),
+                    hir::Mutability::Not => format!("const {}", tymut.ty),
+                };
+
+                if tymut_string != "_" && (tymut.ty.is_simple_text() || tymut_string.len() < "const raw pointer".len()) {
+                    format!("`*{}`", tymut_string).into()
+                } else {
+                    // Unknown type name, it's long or has type arguments
+                    "raw pointer".into()
+                }
+            },
             ty::Ref(_, ty, mutbl) => {
                 let tymut = ty::TypeAndMut { ty, mutbl };
                 let tymut_string = tymut.to_string();
+
                 if tymut_string != "_"
                     && (ty.is_simple_text() || tymut_string.len() < "mutable reference".len())
                 {
diff --git a/src/test/ui/asm/type-check-1.stderr b/src/test/ui/asm/type-check-1.stderr
index 162ff1d32bc44..1845139659db5 100644
--- a/src/test/ui/asm/type-check-1.stderr
+++ b/src/test/ui/asm/type-check-1.stderr
@@ -106,7 +106,7 @@ error[E0308]: mismatched types
   --> $DIR/type-check-1.rs:60:26
    |
 LL |         asm!("{}", const 0 as *mut u8);
-   |                          ^^^^^^^^^^^^ expected integer, found *-ptr
+   |                          ^^^^^^^^^^^^ expected integer, found `*mut u8`
    |
    = note:     expected type `{integer}`
            found raw pointer `*mut u8`
@@ -133,7 +133,7 @@ error[E0308]: mismatched types
   --> $DIR/type-check-1.rs:78:25
    |
 LL | global_asm!("{}", const 0 as *mut u8);
-   |                         ^^^^^^^^^^^^ expected integer, found *-ptr
+   |                         ^^^^^^^^^^^^ expected integer, found `*mut u8`
    |
    = note:     expected type `{integer}`
            found raw pointer `*mut u8`
diff --git a/src/test/ui/dst/dst-bad-coercions.stderr b/src/test/ui/dst/dst-bad-coercions.stderr
index 01f862ed516e9..0d6f4d0209f71 100644
--- a/src/test/ui/dst/dst-bad-coercions.stderr
+++ b/src/test/ui/dst/dst-bad-coercions.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/dst-bad-coercions.rs:14:17
    |
 LL |     let y: &S = x;
-   |            --   ^ expected `&S`, found *-ptr
+   |            --   ^ expected `&S`, found `*const S`
    |            |
    |            expected due to this
    |
@@ -13,7 +13,7 @@ error[E0308]: mismatched types
   --> $DIR/dst-bad-coercions.rs:15:21
    |
 LL |     let y: &dyn T = x;
-   |            ------   ^ expected `&dyn T`, found *-ptr
+   |            ------   ^ expected `&dyn T`, found `*const S`
    |            |
    |            expected due to this
    |
@@ -24,7 +24,7 @@ error[E0308]: mismatched types
   --> $DIR/dst-bad-coercions.rs:19:17
    |
 LL |     let y: &S = x;
-   |            --   ^ expected `&S`, found *-ptr
+   |            --   ^ expected `&S`, found `*mut S`
    |            |
    |            expected due to this
    |
@@ -35,7 +35,7 @@ error[E0308]: mismatched types
   --> $DIR/dst-bad-coercions.rs:20:21
    |
 LL |     let y: &dyn T = x;
-   |            ------   ^ expected `&dyn T`, found *-ptr
+   |            ------   ^ expected `&dyn T`, found `*mut S`
    |            |
    |            expected due to this
    |
diff --git a/src/test/ui/mismatched_types/issue-19109.stderr b/src/test/ui/mismatched_types/issue-19109.stderr
index c25e2687b752a..5cef64bb16926 100644
--- a/src/test/ui/mismatched_types/issue-19109.stderr
+++ b/src/test/ui/mismatched_types/issue-19109.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL | fn function(t: &mut dyn Trait) {
    |                                - help: try adding a return type: `-> *mut dyn Trait`
 LL |     t as *mut dyn Trait
-   |     ^^^^^^^^^^^^^^^^^^^ expected `()`, found *-ptr
+   |     ^^^^^^^^^^^^^^^^^^^ expected `()`, found `*mut dyn Trait`
    |
    = note: expected unit type `()`
             found raw pointer `*mut dyn Trait`