Add check before suggest removing parens

Author: mu001999

compiler/rustc_hir_typeck/src/callee.rs

@@ -599,6 +599,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 = self.typeck_results.borrow().qpath_res(qpath, callee_expr.hir_id)
             // Only suggest removing parens if there are no arguments
             && arg_exprs.is_empty()
+            && call_expr.span.contains(callee_expr.span)
         {
             let descr = match kind {
                 def::CtorOf::Struct => "struct",

tests/ui/suggestions/issue-114701.rs

@@ -0,0 +1,15 @@
+enum Enum<T> { , SVariant { v: T }, UVariant } //~ ERROR expected identifier, found `,`
+
+macro_rules! is_variant {
+    (TSVariant, ) => (!);
+    (SVariant, ) => (!);
+    (UVariant, $expr:expr) => (is_variant!(@check UVariant, {}, $expr));
+    (@check $variant:ident, $matcher:tt, $expr:expr) => (
+        assert!(if let Enum::$variant::<()> $matcher = $expr () else { false }, //~ ERROR this `if` expression
+                );
+    );
+}
+
+fn main() {
+    is_variant!(UVariant, Enum::<()>::UVariant); //~ ERROR expected function
+}

tests/ui/suggestions/issue-114701.stderr

@@ -0,0 +1,48 @@
+error: expected identifier, found `,`
+  --> $DIR/issue-114701.rs:1:16
+   |
+LL | enum Enum<T> { , SVariant { v: T }, UVariant }
+   |                ^
+   |                |
+   |                expected identifier
+   |                help: remove this comma
+
+error: this `if` expression is missing a block after the condition
+  --> $DIR/issue-114701.rs:8:17
+   |
+LL |         assert!(if let Enum::$variant::<()> $matcher = $expr () else { false },
+   |                 ^^
+...
+LL |     is_variant!(UVariant, Enum::<()>::UVariant);
+   |     ------------------------------------------- in this macro invocation
+   |
+help: add a block here
+  --> $DIR/issue-114701.rs:8:64
+   |
+LL |         assert!(if let Enum::$variant::<()> $matcher = $expr () else { false },
+   |                                                                ^
+...
+LL |     is_variant!(UVariant, Enum::<()>::UVariant);
+   |     ------------------------------------------- in this macro invocation
+   = note: this error originates in the macro `is_variant` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: remove the `if` if you meant to write a `let...else` statement
+   |
+LL -         assert!(if let Enum::$variant::<()> $matcher = $expr () else { false },
+LL +         assert!(let Enum::$variant::<()> $matcher = $expr () else { false },
+   |
+
+error[E0618]: expected function, found `Enum<()>`
+  --> $DIR/issue-114701.rs:14:27
+   |
+LL | enum Enum<T> { , SVariant { v: T }, UVariant }
+   |                                     -------- `Enum::UVariant` defined here
+...
+LL |         assert!(if let Enum::$variant::<()> $matcher = $expr () else { false },
+   |                                                        -------- call expression requires function
+...
+LL |     is_variant!(UVariant, Enum::<()>::UVariant);
+   |                           ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0618`.