From 4d16171f563761e19798c220ee415f84d62df26c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Thu, 9 Nov 2023 01:23:10 +0000
Subject: [PATCH] Account for number of arguments in suggestion

---
 .../rustc_resolve/src/late/diagnostics.rs     | 29 ++++++++++++++----
 tests/ui/privacy/suggest-box-new.stderr       | 30 +++++++++----------
 2 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index a0b0abd6555..b0bb9a383db 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -1762,16 +1762,16 @@ fn suggest_alternative_construction_methods(
                     } else {
                         3
                     };
-                    Some((order, item.name))
+                    Some((order, item.name, input_len))
                 } else {
                     None
                 }
             })
             .collect::<Vec<_>>();
-        items.sort_by_key(|(order, _)| *order);
+        items.sort_by_key(|(order, _, _)| *order);
         match &items[..] {
             [] => {}
-            [(_, name)] => {
+            [(_, name, len)] if *len == args.len() => {
                 err.span_suggestion_verbose(
                     path_span.shrink_to_hi(),
                     format!("you might have meant to use the `{name}` associated function",),
@@ -1779,11 +1779,30 @@ fn suggest_alternative_construction_methods(
                     Applicability::MaybeIncorrect,
                 );
             }
+            [(_, name, len)] => {
+                err.span_suggestion_verbose(
+                    path_span.shrink_to_hi().with_hi(call_span.hi()),
+                    format!("you might have meant to use the `{name}` associated function",),
+                    format!(
+                        "::{name}({})",
+                        std::iter::repeat("_").take(*len).collect::<Vec<_>>().join(", ")
+                    ),
+                    Applicability::MaybeIncorrect,
+                );
+            }
             _ => {
                 err.span_suggestions_with_style(
-                    path_span.shrink_to_hi(),
+                    path_span.shrink_to_hi().with_hi(call_span.hi()),
                     "you might have meant to use an associated function to build this type",
-                    items.iter().map(|(_, name)| format!("::{name}")).collect::<Vec<String>>(),
+                    items
+                        .iter()
+                        .map(|(_, name, len)| {
+                            format!(
+                                "::{name}({})",
+                                std::iter::repeat("_").take(*len).collect::<Vec<_>>().join(", ")
+                            )
+                        })
+                        .collect::<Vec<String>>(),
                     Applicability::MaybeIncorrect,
                     SuggestionStyle::ShowAlways,
                 );
diff --git a/tests/ui/privacy/suggest-box-new.stderr b/tests/ui/privacy/suggest-box-new.stderr
index 5fec35dc5c6..2224f1c60d6 100644
--- a/tests/ui/privacy/suggest-box-new.stderr
+++ b/tests/ui/privacy/suggest-box-new.stderr
@@ -10,13 +10,13 @@ LL |     let _ = std::collections::HashMap();
 help: you might have meant to use an associated function to build this type
    |
 LL |     let _ = std::collections::HashMap::new();
-   |                                      +++++
-LL |     let _ = std::collections::HashMap::with_capacity();
-   |                                      +++++++++++++++
-LL |     let _ = std::collections::HashMap::with_hasher();
-   |                                      +++++++++++++
-LL |     let _ = std::collections::HashMap::with_capacity_and_hasher();
-   |                                      ++++++++++++++++++++++++++
+   |                                      ~~~~~~~
+LL |     let _ = std::collections::HashMap::with_capacity(_);
+   |                                      ~~~~~~~~~~~~~~~~~~
+LL |     let _ = std::collections::HashMap::with_hasher(_);
+   |                                      ~~~~~~~~~~~~~~~~
+LL |     let _ = std::collections::HashMap::with_capacity_and_hasher(_, _);
+   |                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 help: consider using the `Default` trait
    |
 LL |     let _ = <std::collections::HashMap as std::default::Default>::default();
@@ -36,14 +36,14 @@ note: constructor is not visible here due to private fields
    = note: private field
 help: you might have meant to use an associated function to build this type
    |
-LL |         wtf: Some(Box::new(U {
-   |                      +++++
-LL |         wtf: Some(Box::new_uninit(U {
-   |                      ++++++++++++
-LL |         wtf: Some(Box::new_zeroed(U {
-   |                      ++++++++++++
-LL |         wtf: Some(Box::new_in(U {
-   |                      ++++++++
+LL |         wtf: Some(Box::new(_)),
+   |                      ~~~~~~~~
+LL |         wtf: Some(Box::new_uninit()),
+   |                      ~~~~~~~~~~~~~~
+LL |         wtf: Some(Box::new_zeroed()),
+   |                      ~~~~~~~~~~~~~~
+LL |         wtf: Some(Box::new_in(_, _)),
+   |                      ~~~~~~~~~~~~~~
      and 10 other candidates
 help: consider using the `Default` trait
    |