2 files changed, 274 insertions, 250 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 67390345f..4c92d0cf4 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -7,6 +7,7 @@
 mod break_outside_of_loop;
 mod inactive_code;
 mod macro_error;
+mod mismatched_arg_count;
 mod missing_fields;
 mod missing_unsafe;
 mod no_such_field;
@@ -224,6 +225,7 @@ pub(crate) fn diagnostics(
             AnyDiagnostic::MacroError(d) => macro_error::macro_error(&ctx, &d),
             AnyDiagnostic::MissingFields(d) => missing_fields::missing_fields(&ctx, &d),
             AnyDiagnostic::MissingUnsafe(d) => missing_unsafe::missing_unsafe(&ctx, &d),
+            AnyDiagnostic::MismatchedArgCount(d) => mismatched_arg_count::mismatched_arg_count(&ctx, &d),
             AnyDiagnostic::NoSuchField(d) => no_such_field::no_such_field(&ctx, &d),
             AnyDiagnostic::UnimplementedBuiltinMacro(d) => unimplemented_builtin_macro::unimplemented_builtin_macro(&ctx, &d),
             AnyDiagnostic::UnresolvedExternCrate(d) => unresolved_extern_crate::unresolved_extern_crate(&ctx, &d),
@@ -837,256 +839,6 @@ fn x(a: S) {
     }
 
     #[test]
-    fn simple_free_fn_zero() {
-        check_diagnostics(
-            r#"
-fn zero() {}
-fn f() { zero(1); }
-       //^^^^^^^ Expected 0 arguments, found 1
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-fn zero() {}
-fn f() { zero(); }
-"#,
-        );
-    }
-
-    #[test]
-    fn simple_free_fn_one() {
-        check_diagnostics(
-            r#"
-fn one(arg: u8) {}
-fn f() { one(); }
-       //^^^^^ Expected 1 argument, found 0
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-fn one(arg: u8) {}
-fn f() { one(1); }
-"#,
-        );
-    }
-
-    #[test]
-    fn method_as_fn() {
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self) {} }
-
-fn f() {
-    S::method();
-} //^^^^^^^^^^^ Expected 1 argument, found 0
-"#,
-        );
-
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self) {} }
-
-fn f() {
-    S::method(&S);
-    S.method();
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn method_with_arg() {
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self, arg: u8) {} }
-
-            fn f() {
-                S.method();
-            } //^^^^^^^^^^ Expected 1 argument, found 0
-            "#,
-        );
-
-        check_diagnostics(
-            r#"
-struct S;
-impl S { fn method(&self, arg: u8) {} }
-
-fn f() {
-    S::method(&S, 0);
-    S.method(1);
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn method_unknown_receiver() {
-        // note: this is incorrect code, so there might be errors on this in the
-        // future, but we shouldn't emit an argument count diagnostic here
-        check_diagnostics(
-            r#"
-trait Foo { fn method(&self, arg: usize) {} }
-
-fn f() {
-    let x;
-    x.method();
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn tuple_struct() {
-        check_diagnostics(
-            r#"
-struct Tup(u8, u16);
-fn f() {
-    Tup(0);
-} //^^^^^^ Expected 2 arguments, found 1
-"#,
-        )
-    }
-
-    #[test]
-    fn enum_variant() {
-        check_diagnostics(
-            r#"
-enum En { Variant(u8, u16), }
-fn f() {
-    En::Variant(0);
-} //^^^^^^^^^^^^^^ Expected 2 arguments, found 1
-"#,
-        )
-    }
-
-    #[test]
-    fn enum_variant_type_macro() {
-        check_diagnostics(
-            r#"
-macro_rules! Type {
-    () => { u32 };
-}
-enum Foo {
-    Bar(Type![])
-}
-impl Foo {
-    fn new() {
-        Foo::Bar(0);
-        Foo::Bar(0, 1);
-      //^^^^^^^^^^^^^^ Expected 1 argument, found 2
-        Foo::Bar();
-      //^^^^^^^^^^ Expected 1 argument, found 0
-    }
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn varargs() {
-        check_diagnostics(
-            r#"
-extern "C" {
-    fn fixed(fixed: u8);
-    fn varargs(fixed: u8, ...);
-    fn varargs2(...);
-}
-
-fn f() {
-    unsafe {
-        fixed(0);
-        fixed(0, 1);
-      //^^^^^^^^^^^ Expected 1 argument, found 2
-        varargs(0);
-        varargs(0, 1);
-        varargs2();
-        varargs2(0);
-        varargs2(0, 1);
-    }
-}
-        "#,
-        )
-    }
-
-    #[test]
-    fn arg_count_lambda() {
-        check_diagnostics(
-            r#"
-fn main() {
-    let f = |()| ();
-    f();
-  //^^^ Expected 1 argument, found 0
-    f(());
-    f((), ());
-  //^^^^^^^^^ Expected 1 argument, found 2
-}
-"#,
-        )
-    }
-
-    #[test]
-    fn cfgd_out_call_arguments() {
-        check_diagnostics(
-            r#"
-struct C(#[cfg(FALSE)] ());
-impl C {
-    fn new() -> Self {
-        Self(
-            #[cfg(FALSE)]
-            (),
-        )
-    }
-
-    fn method(&self) {}
-}
-
-fn main() {
-    C::new().method(#[cfg(FALSE)] 0);
-}
-            "#,
-        );
-    }
-
-    #[test]
-    fn cfgd_out_fn_params() {
-        check_diagnostics(
-            r#"
-fn foo(#[cfg(NEVER)] x: ()) {}
-
-struct S;
-
-impl S {
-    fn method(#[cfg(NEVER)] self) {}
-    fn method2(#[cfg(NEVER)] self, arg: u8) {}
-    fn method3(self, #[cfg(NEVER)] arg: u8) {}
-}
-
-extern "C" {
-    fn fixed(fixed: u8, #[cfg(NEVER)] ...);
-    fn varargs(#[cfg(not(NEVER))] ...);
-}
-
-fn main() {
-    foo();
-    S::method();
-    S::method2(0);
-    S::method3(S);
-    S.method3();
-    unsafe {
-        fixed(0);
-        varargs(1, 2, 3);
-    }
-}
-            "#,
-        )
-    }
-
-    #[test]
     fn missing_semicolon() {
         check_diagnostics(
             r#"
diff --git a/crates/ide/src/diagnostics/mismatched_arg_count.rs b/crates/ide/src/diagnostics/mismatched_arg_count.rs
new file mode 100644
index 000000000..08e1cfa5f
--- /dev/null
+++ b/crates/ide/src/diagnostics/mismatched_arg_count.rs
@@ -0,0 +1,272 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: mismatched-arg-count
+//
+// This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.
+pub(super) fn mismatched_arg_count(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::MismatchedArgCount,
+) -> Diagnostic {
+    let s = if d.expected == 1 { "" } else { "s" };
+    let message = format!("expected {} argument{}, found {}", d.expected, s, d.found);
+    Diagnostic::new(
+        "mismatched-arg-count",
+        message,
+        ctx.sema.diagnostics_display_range(d.call_expr.clone().map(|it| it.into())).range,
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::check_diagnostics;
+
+    #[test]
+    fn simple_free_fn_zero() {
+        check_diagnostics(
+            r#"
+fn zero() {}
+fn f() { zero(1); }
+       //^^^^^^^ expected 0 arguments, found 1
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+fn zero() {}
+fn f() { zero(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn simple_free_fn_one() {
+        check_diagnostics(
+            r#"
+fn one(arg: u8) {}
+fn f() { one(); }
+       //^^^^^ expected 1 argument, found 0
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+fn one(arg: u8) {}
+fn f() { one(1); }
+"#,
+        );
+    }
+
+    #[test]
+    fn method_as_fn() {
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self) {} }
+
+fn f() {
+    S::method();
+} //^^^^^^^^^^^ expected 1 argument, found 0
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self) {} }
+
+fn f() {
+    S::method(&S);
+    S.method();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn method_with_arg() {
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self, arg: u8) {} }
+
+            fn f() {
+                S.method();
+            } //^^^^^^^^^^ expected 1 argument, found 0
+            "#,
+        );
+
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self, arg: u8) {} }
+
+fn f() {
+    S::method(&S, 0);
+    S.method(1);
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn method_unknown_receiver() {
+        // note: this is incorrect code, so there might be errors on this in the
+        // future, but we shouldn't emit an argument count diagnostic here
+        check_diagnostics(
+            r#"
+trait Foo { fn method(&self, arg: usize) {} }
+
+fn f() {
+    let x;
+    x.method();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_struct() {
+        check_diagnostics(
+            r#"
+struct Tup(u8, u16);
+fn f() {
+    Tup(0);
+} //^^^^^^ expected 2 arguments, found 1
+"#,
+        )
+    }
+
+    #[test]
+    fn enum_variant() {
+        check_diagnostics(
+            r#"
+enum En { Variant(u8, u16), }
+fn f() {
+    En::Variant(0);
+} //^^^^^^^^^^^^^^ expected 2 arguments, found 1
+"#,
+        )
+    }
+
+    #[test]
+    fn enum_variant_type_macro() {
+        check_diagnostics(
+            r#"
+macro_rules! Type {
+    () => { u32 };
+}
+enum Foo {
+    Bar(Type![])
+}
+impl Foo {
+    fn new() {
+        Foo::Bar(0);
+        Foo::Bar(0, 1);
+      //^^^^^^^^^^^^^^ expected 1 argument, found 2
+        Foo::Bar();
+      //^^^^^^^^^^ expected 1 argument, found 0
+    }
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn varargs() {
+        check_diagnostics(
+            r#"
+extern "C" {
+    fn fixed(fixed: u8);
+    fn varargs(fixed: u8, ...);
+    fn varargs2(...);
+}
+
+fn f() {
+    unsafe {
+        fixed(0);
+        fixed(0, 1);
+      //^^^^^^^^^^^ expected 1 argument, found 2
+        varargs(0);
+        varargs(0, 1);
+        varargs2();
+        varargs2(0);
+        varargs2(0, 1);
+    }
+}
+        "#,
+        )
+    }
+
+    #[test]
+    fn arg_count_lambda() {
+        check_diagnostics(
+            r#"
+fn main() {
+    let f = |()| ();
+    f();
+  //^^^ expected 1 argument, found 0
+    f(());
+    f((), ());
+  //^^^^^^^^^ expected 1 argument, found 2
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn cfgd_out_call_arguments() {
+        check_diagnostics(
+            r#"
+struct C(#[cfg(FALSE)] ());
+impl C {
+    fn new() -> Self {
+        Self(
+            #[cfg(FALSE)]
+            (),
+        )
+    }
+
+    fn method(&self) {}
+}
+
+fn main() {
+    C::new().method(#[cfg(FALSE)] 0);
+}
+            "#,
+        );
+    }
+
+    #[test]
+    fn cfgd_out_fn_params() {
+        check_diagnostics(
+            r#"
+fn foo(#[cfg(NEVER)] x: ()) {}
+
+struct S;
+
+impl S {
+    fn method(#[cfg(NEVER)] self) {}
+    fn method2(#[cfg(NEVER)] self, arg: u8) {}
+    fn method3(self, #[cfg(NEVER)] arg: u8) {}
+}
+
+extern "C" {
+    fn fixed(fixed: u8, #[cfg(NEVER)] ...);
+    fn varargs(#[cfg(not(NEVER))] ...);
+}
+
+fn main() {
+    foo();
+    S::method();
+    S::method2(0);
+    S::method3(S);
+    S.method3();
+    unsafe {
+        fixed(0);
+        varargs(1, 2, 3);
+    }
+}
+            "#,
+        )
+    }
+}