Keep space if arg does not follow punctuation when lint unused parens

compiler/rustc_lint/src/unused.rs

@@ -843,6 +843,10 @@ trait UnusedDelimLint {
  && !snip.ends_with(' ')
  {
  " "
+ } else if let Ok(snip) = sm.span_to_prev_source(value_span)
+ && snip.ends_with(|c: char| c.is_alphanumeric())
+ {
+ " "
  } else {
  ""
  };
@@ -852,6 +856,10 @@ trait UnusedDelimLint {
  && !snip.starts_with(' ')
  {
  " "
+ } else if let Ok(snip) = sm.span_to_prev_source(value_span)
+ && snip.starts_with(|c: char| c.is_alphanumeric())
+ {
+ " "
  } else {
  ""
  };

tests/ui/lint/unused_parens_follow_ident.fixed

@@ -0,0 +1,17 @@
+//@ run-rustfix
+
+#![deny(unused_parens)]
+
+macro_rules! wrap {
+ ($name:ident $arg:expr) => {
+ $name($arg);
+ };
+}
+
+fn main() {
+ wrap!(unary routine()); //~ ERROR unnecessary parentheses around function argument
+ wrap!(unary routine()); //~ ERROR unnecessary parentheses around function argument
+}
+
+fn unary(_: ()) {}
+fn routine() {}

tests/ui/lint/unused_parens_follow_ident.rs

@@ -0,0 +1,17 @@
+//@ run-rustfix
+
+#![deny(unused_parens)]
+
+macro_rules! wrap {
+ ($name:ident $arg:expr) => {
+ $name($arg);
+ };
+}
+
+fn main() {
+ wrap!(unary(routine())); //~ ERROR unnecessary parentheses around function argument
+ wrap!(unary (routine())); //~ ERROR unnecessary parentheses around function argument
+}
+
+fn unary(_: ()) {}
+fn routine() {}

tests/ui/lint/unused_parens_follow_ident.stderr

@@ -0,0 +1,31 @@
+error: unnecessary parentheses around function argument
+ --> $DIR/unused_parens_follow_ident.rs:12:16
+ |
+LL | wrap!(unary(routine()));
+ | ^ ^
+ |
+note: the lint level is defined here
+ --> $DIR/unused_parens_follow_ident.rs:3:9
+ |
+LL | #![deny(unused_parens)]
+ | ^^^^^^^^^^^^^
+help: remove these parentheses
+ |
+LL - wrap!(unary(routine()));
+LL + wrap!(unary routine());
+ |
+
+error: unnecessary parentheses around function argument
+ --> $DIR/unused_parens_follow_ident.rs:13:17
+ |
+LL | wrap!(unary (routine()));
+ | ^ ^
+ |
+help: remove these parentheses
+ |
+LL - wrap!(unary (routine()));
+LL + wrap!(unary routine());
+ |
+
+error: aborting due to 2 previous errors
+