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

compiler/rustc_span/src/symbol.rs

@@ -1027,6 +1027,7 @@ symbols! {
         format_args_capture,
         format_args_macro,
         format_args_nl,
+        format_args_nl_macro,
         format_argument,
         format_arguments,
         format_count,

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::{ErrorGuaranteed, ExpnKind, Span, sym};
 use tracing::{info, instrument};
 
 pub use self::overflow::*;
@@ -136,6 +136,15 @@ pub enum DefIdOrName {
     Name(&'static str),
 }
 
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum ErrorSortKey {
+    SubtypeFormat(usize, usize),
+    OtherKind,
+    ClauseTraitSized,
+    Coerce,
+    ClauseWellFormed,
+}
+
 impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     pub fn report_fulfillment_errors(
         &self,
@@ -162,15 +171,36 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
         // Ensure `T: Sized` and `T: WF` obligations come last. This lets us display diagnostics
         // with more relevant type information and hide redundant E0282 errors.
-        errors.sort_by_key(|e| match e.obligation.predicate.kind().skip_binder() {
-            ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred))
-                if self.tcx.is_lang_item(pred.def_id(), LangItem::Sized) =>
-            {
-                1
+        errors.sort_by_key(|e| {
+            let span = e.obligation.cause.span;
+            let outer_expn_data = span.ctxt().outer_expn_data();
+            let source_span = outer_expn_data.call_site.source_callsite();
+            let source_map = self.tcx.sess.source_map();
+
+            match e.obligation.predicate.kind().skip_binder() {
+                ty::PredicateKind::Subtype(_)
+                    if let Some(def_id) = outer_expn_data.macro_def_id
+                        && let (Some(span_file), row, col, ..) =
+                            source_map.span_to_location_info(span)
+                        && let (Some(source_file), ..) =
+                            source_map.span_to_location_info(source_span)
+                        && (self.tcx.is_diagnostic_item(sym::format_args_nl_macro, def_id)
+                            || self.tcx.is_diagnostic_item(sym::format_args_macro, def_id))
+                        && span_file.src_hash == source_file.src_hash =>
+                {
+                    ErrorSortKey::SubtypeFormat(row, col)
+                }
+                ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred))
+                    if self.tcx.is_lang_item(pred.def_id(), LangItem::Sized) =>
+                {
+                    ErrorSortKey::ClauseTraitSized
+                }
+                ty::PredicateKind::Coerce(_) => ErrorSortKey::Coerce,
+                ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => {
+                    ErrorSortKey::ClauseWellFormed
+                }
+                _ => ErrorSortKey::OtherKind,
             }
-            ty::PredicateKind::Coerce(_) => 2,
-            ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => 3,
-            _ => 0,
         });
 
         for (index, error) in errors.iter().enumerate() {

library/core/src/macros/mod.rs

@@ -1027,6 +1027,7 @@ pub(crate) mod builtin {
         reason = "`format_args_nl` is only for internal \
                   language use and is subject to change"
     )]
+    #[rustc_diagnostic_item = "format_args_nl_macro"]
     #[allow_internal_unstable(fmt_internals)]
     #[rustc_builtin_macro]
     #[macro_export]

tests/ui/errors/span-format_args-issue-140578.rs

@@ -0,0 +1,32 @@
+fn check_format_args() {
+  print!("{:?} {a} {a:?}", [], a = 1 + 1);
+  //~^ ERROR type annotations needed
+}
+
+fn check_format_args_nl() {
+  println!("{:?} {a} {a:?}", [], a = 1 + 1);
+  //~^ ERROR type annotations needed
+}
+
+fn check_multi1() {
+  println!("{:?} {:?} {a} {a:?}", [], [], a = 1 + 1);
+  //~^ ERROR type annotations needed
+}
+
+fn check_multi2() {
+  println!("{:?} {:?} {a} {a:?} {b:?}", [], [], a = 1 + 1, b = []);
+  //~^ ERROR type annotations needed
+}
+
+fn check_unformatted() {
+  println!("
+  {:?} {:?}
+{a}
+{a:?}",
+        [],
+        //~^ ERROR type annotations needed
+ [],
+a = 1 + 1);
+}
+
+fn main() {}

tests/ui/errors/span-format_args-issue-140578.stderr

@@ -0,0 +1,43 @@
+error[E0282]: type annotations needed
+  --> $DIR/span-format_args-issue-140578.rs:2:28
+   |
+LL |   print!("{:?} {a} {a:?}", [], a = 1 + 1);
+   |                            ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$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
+  --> $DIR/span-format_args-issue-140578.rs:7:30
+   |
+LL |   println!("{:?} {a} {a:?}", [], a = 1 + 1);
+   |                              ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$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[E0282]: type annotations needed
+  --> $DIR/span-format_args-issue-140578.rs:12:35
+   |
+LL |   println!("{:?} {:?} {a} {a:?}", [], [], a = 1 + 1);
+   |                                   ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$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[E0282]: type annotations needed
+  --> $DIR/span-format_args-issue-140578.rs:17:41
+   |
+LL |   println!("{:?} {:?} {a} {a:?} {b:?}", [], [], a = 1 + 1, b = []);
+   |                                         ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$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[E0282]: type annotations needed
+  --> $DIR/span-format_args-issue-140578.rs:26:9
+   |
+LL |         [],
+   |         ^^ cannot infer type
+   |
+   = note: this error originates in the macro `$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
+
+For more information about this error, try `rustc --explain E0282`.