fix: implicit_haser wrongly unmangled macros

Author: profetia

clippy_lints/src/implicit_hasher.rs

@@ -13,7 +13,7 @@ use rustc_session::declare_lint_pass;
 use rustc_span::Span;
 
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::source::{IntoSpan, SpanRangeExt, snippet};
+use clippy_utils::source::{IntoSpan, SpanRangeExt, snippet, snippet_with_context};
 use clippy_utils::sym;
 
 declare_clippy_lint! {
@@ -335,29 +335,23 @@ impl<'tcx> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'_, '_, 'tcx> {
                 return;
             }
 
-            match (self.cx.tcx.get_diagnostic_name(ty_did), method.ident.name) {
-                (Some(sym::HashMap), sym::new) => {
-                    self.suggestions.insert(e.span, "HashMap::default()".to_string());
-                },
-                (Some(sym::HashMap), sym::with_capacity) => {
-                    self.suggestions.insert(
-                        e.span,
-                        format!(
-                            "HashMap::with_capacity_and_hasher({}, Default::default())",
-                            snippet(self.cx, args[0].span, "capacity"),
-                        ),
-                    );
-                },
-                (Some(sym::HashSet), sym::new) => {
-                    self.suggestions.insert(e.span, "HashSet::default()".to_string());
+            let container_name = match self.cx.tcx.get_diagnostic_name(ty_did) {
+                Some(sym::HashMap) => "HashMap",
+                Some(sym::HashSet) => "HashSet",
+                _ => return,
+            };
+
+            match method.ident.name {
+                sym::new => {
+                    self.suggestions.insert(e.span, format!("{container_name}::default()"));
                 },
-                (Some(sym::HashSet), sym::with_capacity) => {
+                sym::with_capacity => {
+                    let mut applicability = Applicability::MachineApplicable;
+                    let (arg_snippet, _) =
+                        snippet_with_context(self.cx, args[0].span, e.span.ctxt(), "..", &mut applicability);
                     self.suggestions.insert(
                         e.span,
-                        format!(
-                            "HashSet::with_capacity_and_hasher({}, Default::default())",
-                            snippet(self.cx, args[0].span, "capacity"),
-                        ),
+                        format!("{container_name}::with_capacity_and_hasher({arg_snippet}, Default::default())",),
                     );
                 },
                 _ => {},

tests/ui/implicit_hasher.fixed

@@ -109,3 +109,20 @@ pub async fn election_vote<S: ::std::hash::BuildHasher>(_data: HashMap<i32, i32,
 //~^ implicit_hasher
 
 fn main() {}
+
+mod issue16128 {
+    use super::*;
+
+    impl<K: Hash + Eq, V, S: ::std::hash::BuildHasher + Default> Foo<u64> for HashMap<K, V, S> {
+        //~^ implicit_hasher
+        fn make() -> (Self, Self) {
+            macro_rules! times_by_ten {
+                ($num:expr) => {
+                    $num * 10
+                };
+            }
+
+            (HashMap::default(), HashMap::with_capacity_and_hasher(times_by_ten!(5), Default::default()))
+        }
+    }
+}

tests/ui/implicit_hasher.rs

@@ -109,3 +109,20 @@ pub async fn election_vote(_data: HashMap<i32, i32>) {}
 //~^ implicit_hasher
 
 fn main() {}
+
+mod issue16128 {
+    use super::*;
+
+    impl<K: Hash + Eq, V> Foo<u64> for HashMap<K, V> {
+        //~^ implicit_hasher
+        fn make() -> (Self, Self) {
+            macro_rules! times_by_ten {
+                ($num:expr) => {
+                    $num * 10
+                };
+            }
+
+            (HashMap::new(), HashMap::with_capacity(times_by_ten!(5)))
+        }
+    }
+}

tests/ui/implicit_hasher.stderr

@@ -122,5 +122,20 @@ help: add a type parameter for `BuildHasher`
 LL | pub async fn election_vote<S: ::std::hash::BuildHasher>(_data: HashMap<i32, i32, S>) {}
    |                           +++++++++++++++++++++++++++++                        +++
 
-error: aborting due to 9 previous errors
+error: impl for `HashMap` should be generalized over different hashers
+  --> tests/ui/implicit_hasher.rs:116:40
+   |
+LL |     impl<K: Hash + Eq, V> Foo<u64> for HashMap<K, V> {
+   |                                        ^^^^^^^^^^^^^
+   |
+help: add a type parameter for `BuildHasher`
+   |
+LL ~     impl<K: Hash + Eq, V, S: ::std::hash::BuildHasher + Default> Foo<u64> for HashMap<K, V, S> {
+LL |
+...
+LL |
+LL ~             (HashMap::default(), HashMap::with_capacity_and_hasher(times_by_ten!(5), Default::default()))
+   |
+
+error: aborting due to 10 previous errors