Add test for unuseful span in type error in some format_args!() invocations

Author: moatom

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`.