fix(run): Say what the multiple executables are

Author: epage

src/cargo/ops/cargo_run.rs

@@ -1,4 +1,5 @@
 use std::ffi::OsString;
+use std::fmt::Write as _;
 use std::iter;
 use std::path::Path;
 
@@ -69,10 +70,20 @@ pub fn run(
                 names.join(", ")
             )
         } else {
-            anyhow::bail!(
-                "`cargo run` can run at most one executable, but \
+            let mut message = "`cargo run` can run at most one executable, but \
                  multiple were specified"
-            )
+                .to_owned();
+            write!(&mut message, "\nhelp: available targets:")?;
+            for (pkg, bin) in &bins {
+                write!(
+                    &mut message,
+                    "\n    {} `{}` in package `{}`",
+                    bin.kind().description(),
+                    bin.name(),
+                    pkg.name()
+                )?;
+            }
+            anyhow::bail!(message)
         }
     }
 

tests/testsuite/run.rs

@@ -836,6 +836,11 @@ fn ambiguous_bin_name() {
         .with_status(101)
         .with_stderr_data(str![[r#"
 [ERROR] `cargo run` can run at most one executable, but multiple were specified
+[HELP] available targets:
+    bin `ambiguous` in package `crate1`
+    bin `ambiguous` in package `crate2`
+    bin `ambiguous` in package `crate3`
+    bin `ambiguous` in package `crate4`
 
 "#]])
         .run();
@@ -1014,6 +1019,9 @@ fn either_name_or_example() {
         .with_status(101)
         .with_stderr_data(str![[r#"
 [ERROR] `cargo run` can run at most one executable, but multiple were specified
+[HELP] available targets:
+    bin `a` in package `foo`
+    example `b` in package `foo`
 
 "#]])
         .run();