Fix println_empty_string suggestion caused error (#16201)

Closes: rust-lang/rust-clippy#16167
changelog: [`println_empty_string`]: fix suggestion caused error when
there is a comma after arg.

Closes: rust-lang/rust-clippy#16251
changelog: [`writeln_empty_string`]: fix suggestion caused error when
there is a comma in the comment before arg.

clippy_lints/src/write/empty_string.rs

@@ -1,37 +1,43 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::macros::MacroCall;
 use clippy_utils::source::expand_past_previous_comma;
-use clippy_utils::sym;
+use clippy_utils::{span_extract_comments, sym};
 use rustc_ast::{FormatArgs, FormatArgsPiece};
 use rustc_errors::Applicability;
-use rustc_lint::LateContext;
+use rustc_lint::{LateContext, LintContext};
 
 use super::{PRINTLN_EMPTY_STRING, WRITELN_EMPTY_STRING};
 
 pub(super) fn check(cx: &LateContext<'_>, format_args: &FormatArgs, macro_call: &MacroCall, name: &str) {
     if let [FormatArgsPiece::Literal(sym::LF)] = &format_args.template[..] {
-        let mut span = format_args.span;
-
-        let lint = if name == "writeln" {
-            span = expand_past_previous_comma(cx, span);
-
-            WRITELN_EMPTY_STRING
-        } else {
-            PRINTLN_EMPTY_STRING
-        };
+        let is_writeln = name == "writeln";
 
         span_lint_and_then(
             cx,
-            lint,
+            if is_writeln {
+                WRITELN_EMPTY_STRING
+            } else {
+                PRINTLN_EMPTY_STRING
+            },
             macro_call.span,
             format!("empty string literal in `{name}!`"),
             |diag| {
-                diag.span_suggestion(
-                    span,
-                    "remove the empty string",
-                    String::new(),
-                    Applicability::MachineApplicable,
-                );
+                if span_extract_comments(cx.sess().source_map(), macro_call.span).is_empty() {
+                    let closing_paren = cx.sess().source_map().span_extend_to_prev_char_before(
+                        macro_call.span.shrink_to_hi(),
+                        ')',
+                        false,
+                    );
+                    let mut span = format_args.span.with_hi(closing_paren.lo());
+                    if is_writeln {
+                        span = expand_past_previous_comma(cx, span);
+                    }
+
+                    diag.span_suggestion(span, "remove the empty string", "", Applicability::MachineApplicable);
+                } else {
+                    // If there is a comment in the span of macro call, we don't provide an auto-fix suggestion.
+                    diag.span_note(format_args.span, "remove the empty string");
+                }
             },
         );
     }

tests/ui/crashes/ice-10148.stderr

@@ -2,7 +2,7 @@ error: empty string literal in `println!`
   --> tests/ui/crashes/ice-10148.rs:8:5
    |
 LL |     println!(with_span!(""something ""));
-   |     ^^^^^^^^^^^^^^^^^^^^-----------^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^---------------^
    |                         |
    |                         help: remove the empty string
    |

tests/ui/println_empty_string.fixed

@@ -19,3 +19,23 @@ fn main() {
         //~^ println_empty_string
     }
 }
+
+#[rustfmt::skip]
+fn issue_16167() {
+    //~v println_empty_string
+    println!(
+        );
+
+    match "a" {
+        _ => println!(), // there is a space between "" and comma
+        //~^ println_empty_string
+    }
+
+    eprintln!(); // there is a tab between "" and comma
+    //~^ println_empty_string
+
+    match "a" {
+        _ => eprintln!(), // tab and space between "" and comma
+        //~^ println_empty_string
+    }
+}

tests/ui/println_empty_string.rs

@@ -19,3 +19,27 @@ fn main() {
         //~^ println_empty_string
     }
 }
+
+#[rustfmt::skip]
+fn issue_16167() {
+    //~v println_empty_string
+    println!(
+        "\
+            \
+            "
+            ,
+    );
+
+    match "a" {
+        _ => println!("" ,), // there is a space between "" and comma
+        //~^ println_empty_string
+    }
+
+    eprintln!(""	,); // there is a tab between "" and comma
+    //~^ println_empty_string
+
+    match "a" {
+        _ => eprintln!(""	 ,), // tab and space between "" and comma
+        //~^ println_empty_string
+    }
+}

tests/ui/println_empty_string.stderr

@@ -33,5 +33,42 @@ LL |         _ => eprintln!(""),
    |                        |
    |                        help: remove the empty string
 
-error: aborting due to 4 previous errors
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string.rs:26:5
+   |
+LL | /      println!(
+LL | |/         "\
+LL | ||             \
+LL | ||             "
+LL | ||             ,
+LL | ||     );
+   | ||____-^
+   |  |____|
+   |       help: remove the empty string
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string.rs:34:14
+   |
+LL |         _ => println!("" ,), // there is a space between "" and comma
+   |              ^^^^^^^^^----^
+   |                       |
+   |                       help: remove the empty string
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:38:5
+   |
+LL |     eprintln!(""    ,); // there is a tab between "" and comma
+   |     ^^^^^^^^^^-------^
+   |               |
+   |               help: remove the empty string
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:42:14
+   |
+LL |         _ => eprintln!(""     ,), // tab and space between "" and comma
+   |              ^^^^^^^^^^--------^
+   |                        |
+   |                        help: remove the empty string
+
+error: aborting due to 8 previous errors
 

tests/ui/println_empty_string_unfixable.rs

@@ -0,0 +1,30 @@
+#![allow(clippy::match_single_binding)]
+
+// If there is a comment in the span of macro call, we don't provide an auto-fix suggestion.
+#[rustfmt::skip]
+fn issue_16167() {
+    //~v println_empty_string
+    println!("" /* comment */);
+    //~v println_empty_string
+    eprintln!("" /* comment */);
+
+    //~v println_empty_string
+    println!( // comment
+                "");
+    //~v println_empty_string
+    eprintln!( // comment
+                "");
+
+    //~v println_empty_string
+    println!("", /* comment */);
+
+    //~v println_empty_string
+    println!(
+        "\
+            \
+            ",
+
+    // there is a comment in the macro span regardless of its position
+
+    );
+}

tests/ui/println_empty_string_unfixable.stderr

@@ -0,0 +1,85 @@
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string_unfixable.rs:7:5
+   |
+LL |     println!("" /* comment */);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:7:14
+   |
+LL |     println!("" /* comment */);
+   |              ^^
+   = note: `-D clippy::println-empty-string` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::println_empty_string)]`
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string_unfixable.rs:9:5
+   |
+LL |     eprintln!("" /* comment */);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:9:15
+   |
+LL |     eprintln!("" /* comment */);
+   |               ^^
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string_unfixable.rs:12:5
+   |
+LL | /     println!( // comment
+LL | |                 "");
+   | |___________________^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:13:17
+   |
+LL |                 "");
+   |                 ^^
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string_unfixable.rs:15:5
+   |
+LL | /     eprintln!( // comment
+LL | |                 "");
+   | |___________________^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:16:17
+   |
+LL |                 "");
+   |                 ^^
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string_unfixable.rs:19:5
+   |
+LL |     println!("", /* comment */);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:19:14
+   |
+LL |     println!("", /* comment */);
+   |              ^^
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string_unfixable.rs:22:5
+   |
+LL | /     println!(
+LL | |         "\
+LL | |             \
+LL | |             ",
+...  |
+LL | |     );
+   | |_____^
+   |
+note: remove the empty string
+  --> tests/ui/println_empty_string_unfixable.rs:23:9
+   |
+LL | /         "\
+LL | |             \
+LL | |             ",
+   | |_____________^
+
+error: aborting due to 6 previous errors
+

tests/ui/writeln_empty_string_unfixable.rs

@@ -0,0 +1,26 @@
+#![allow(unused_must_use)]
+#![warn(clippy::writeln_empty_string)]
+
+use std::io::Write;
+
+// If there is a comment in the span of macro call, we don't provide an auto-fix suggestion.
+#[rustfmt::skip]
+fn issue_16251() {
+    let mut v = Vec::new();
+
+    writeln!(v, /* comment */ "");
+    //~^ writeln_empty_string
+
+    writeln!(v, "" /* comment */);
+    //~^ writeln_empty_string
+
+    //~v writeln_empty_string
+    writeln!(v,
+        "\
+            \
+            "
+
+    // there is a comment in the macro span regardless of its position
+
+    );
+}

tests/ui/writeln_empty_string_unfixable.stderr

@@ -0,0 +1,47 @@
+error: empty string literal in `writeln!`
+  --> tests/ui/writeln_empty_string_unfixable.rs:11:5
+   |
+LL |     writeln!(v, /* comment */ "");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: remove the empty string
+  --> tests/ui/writeln_empty_string_unfixable.rs:11:31
+   |
+LL |     writeln!(v, /* comment */ "");
+   |                               ^^
+   = note: `-D clippy::writeln-empty-string` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::writeln_empty_string)]`
+
+error: empty string literal in `writeln!`
+  --> tests/ui/writeln_empty_string_unfixable.rs:14:5
+   |
+LL |     writeln!(v, "" /* comment */);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: remove the empty string
+  --> tests/ui/writeln_empty_string_unfixable.rs:14:17
+   |
+LL |     writeln!(v, "" /* comment */);
+   |                 ^^
+
+error: empty string literal in `writeln!`
+  --> tests/ui/writeln_empty_string_unfixable.rs:18:5
+   |
+LL | /     writeln!(v,
+LL | |         "\
+LL | |             \
+LL | |             "
+...  |
+LL | |     );
+   | |_____^
+   |
+note: remove the empty string
+  --> tests/ui/writeln_empty_string_unfixable.rs:19:9
+   |
+LL | /         "\
+LL | |             \
+LL | |             "
+   | |_____________^
+
+error: aborting due to 3 previous errors
+