Fix unuseful span in type error in some format_args!() invocations

4 files changed, 60 insertions, 36 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
index b3d1b8e3888..9052031ce4f 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
@@ -21,7 +21,7 @@ use rustc_infer::traits::{
 };
 use rustc_middle::ty::print::{PrintTraitRefExt as _, with_no_trimmed_paths};
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::{ErrorGuaranteed, ExpnKind, Span};
+use rustc_span::{DesugaringKind, ErrorGuaranteed, ExpnKind, Span};
 use tracing::{info, instrument};
 
 pub use self::overflow::*;
@@ -154,9 +154,20 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             })
             .collect();
 
-        // Ensure `T: Sized`, `T: MetaSized`, `T: PointeeSized` and `T: WF` obligations come last.
+        // Ensure `T: Sized`, `T: MetaSized`, `T: PointeeSized` and `T: WF` obligations come last,
+        // and `Subtype` obligations from `FormatLiteral` desugarings come first.
         // This lets us display diagnostics with more relevant type information and hide redundant
         // E0282 errors.
+        #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+        enum ErrorSortKey {
+            SubtypeFormat(usize, usize),
+            OtherKind,
+            SizedTrait,
+            MetaSizedTrait,
+            PointeeSizedTrait,
+            Coerce,
+            WellFormed,
+        }
         errors.sort_by_key(|e| {
             let maybe_sizedness_did = match e.obligation.predicate.kind().skip_binder() {
                 ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => Some(pred.def_id()),
@@ -165,12 +176,30 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             };
 
             match e.obligation.predicate.kind().skip_binder() {
-                _ if maybe_sizedness_did == self.tcx.lang_items().sized_trait() => 1,
-                _ if maybe_sizedness_did == self.tcx.lang_items().meta_sized_trait() => 2,
-                _ if maybe_sizedness_did == self.tcx.lang_items().pointee_sized_trait() => 3,
-                ty::PredicateKind::Coerce(_) => 4,
-                ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => 5,
-                _ => 0,
+                ty::PredicateKind::Subtype(_)
+                    if matches!(
+                        e.obligation.cause.span.desugaring_kind(),
+                        Some(DesugaringKind::FormatLiteral { .. })
+                    ) =>
+                {
+                    let (_, row, col, ..) =
+                        self.tcx.sess.source_map().span_to_location_info(e.obligation.cause.span);
+                    ErrorSortKey::SubtypeFormat(row, col)
+                }
+                _ if maybe_sizedness_did == self.tcx.lang_items().sized_trait() => {
+                    ErrorSortKey::SizedTrait
+                }
+                _ if maybe_sizedness_did == self.tcx.lang_items().meta_sized_trait() => {
+                    ErrorSortKey::MetaSizedTrait
+                }
+                _ if maybe_sizedness_did == self.tcx.lang_items().pointee_sized_trait() => {
+                    ErrorSortKey::PointeeSizedTrait
+                }
+                ty::PredicateKind::Coerce(_) => ErrorSortKey::Coerce,
+                ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => {
+                    ErrorSortKey::WellFormed
+                }
+                _ => ErrorSortKey::OtherKind,
             }
         });
 
diff --git a/tests/ui/errors/span-format_args-issue-140578.rs b/tests/ui/errors/span-format_args-issue-140578.rs
index d086fde09f7..8c91ded8337 100644
--- a/tests/ui/errors/span-format_args-issue-140578.rs
+++ b/tests/ui/errors/span-format_args-issue-140578.rs
@@ -19,11 +19,12 @@ fn check_multi2() {
 }
 
 fn check_unformatted() {
-  println!(" //~ ERROR type annotations needed
+  println!("
   {:?} {:?}
 {a}
 {a:?}",
         [],
+        //~^ ERROR type annotations needed
  [],
 a = 1 + 1);
 }
diff --git a/tests/ui/errors/span-format_args-issue-140578.stderr b/tests/ui/errors/span-format_args-issue-140578.stderr
index 4c19b491959..6a273e5cd51 100644
--- a/tests/ui/errors/span-format_args-issue-140578.stderr
+++ b/tests/ui/errors/span-format_args-issue-140578.stderr
@@ -1,48 +1,42 @@
 error[E0282]: type annotations needed
-  --> $DIR/span-format_args-issue-140578.rs:2:3
+  --> $DIR/span-format_args-issue-140578.rs:2:28
    |
 LL |   print!("{:?} {a} {a:?}", [], a = 1 + 1);
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                            ^^ cannot infer type
    |
-   = note: this error originates in the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::format_args` which comes from the expansion of the macro `print` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0282]: type annotations needed
-  --> $DIR/span-format_args-issue-140578.rs:7:3
+  --> $DIR/span-format_args-issue-140578.rs:7:30
    |
 LL |   println!("{:?} {a} {a:?}", [], a = 1 + 1);
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                              ^^ cannot infer type
    |
-   = note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0282]: type annotations needed
-  --> $DIR/span-format_args-issue-140578.rs:12:3
+  --> $DIR/span-format_args-issue-140578.rs:12:35
    |
 LL |   println!("{:?} {:?} {a} {a:?}", [], [], a = 1 + 1);
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                                   ^^ cannot infer type
    |
-   = note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0282]: type annotations needed
-  --> $DIR/span-format_args-issue-140578.rs:17:3
+  --> $DIR/span-format_args-issue-140578.rs:17:41
    |
 LL |   println!("{:?} {:?} {a} {a:?} {b:?}", [], [], a = 1 + 1, b = []);
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                                         ^^ cannot infer type
    |
-   = note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0282]: type annotations needed
-  --> $DIR/span-format_args-issue-140578.rs:22:3
-   |
-LL | /   println!("
-LL | |   {:?} {:?}
-LL | | {a}
-LL | | {a:?}",
-LL | |         [],
-LL | |  [],
-LL | | a = 1 + 1);
-   | |__________^ cannot infer type
-   |
-   = note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+  --> $DIR/span-format_args-issue-140578.rs:26:9
+   |
+LL |         [],
+   |         ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 5 previous errors
 
diff --git a/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr
index a78941f9e11..3de317d2af6 100644
--- a/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr
+++ b/tests/ui/inference/need_type_info/issue-107745-avoid-expr-from-macro-expansion.stderr
@@ -1,10 +1,10 @@
 error[E0282]: type annotations needed
-  --> $DIR/issue-107745-avoid-expr-from-macro-expansion.rs:17:5
+  --> $DIR/issue-107745-avoid-expr-from-macro-expansion.rs:17:22
    |
 LL |     println!("{:?}", []);
-   |     ^^^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                      ^^ cannot infer type
    |
-   = note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error