Fix println_empty_string suggestion caused error when there is a , after arg

Author: relaxcn

clippy_lints/src/write/empty_string.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::macros::MacroCall;
-use clippy_utils::source::expand_past_previous_comma;
+use clippy_utils::source::{expand_past_next_comma, expand_past_previous_comma};
 use clippy_utils::sym;
 use rustc_ast::{FormatArgs, FormatArgsPiece};
 use rustc_errors::Applicability;
@@ -17,6 +17,10 @@ pub(super) fn check(cx: &LateContext<'_>, format_args: &FormatArgs, macro_call:
 
             WRITELN_EMPTY_STRING
         } else {
+            span = Some(expand_past_next_comma(cx, span))
+                .filter(|s| macro_call.span.contains(*s))
+                .unwrap_or(span);
+
             PRINTLN_EMPTY_STRING
         };
 

clippy_utils/src/source.rs

@@ -759,6 +759,16 @@ pub fn expand_past_previous_comma(sess: &impl HasSession, span: Span) -> Span {
     extended.with_lo(extended.lo() - BytePos(1))
 }
 
+/// Expand a span to include a following comma
+/// ```rust,ignore
+/// println!("" ,)   -> println!("" ,)
+///          ^^                  ^^^^
+/// ```
+pub fn expand_past_next_comma(sess: &impl HasSession, span: Span) -> Span {
+    let extended = sess.sess().source_map().span_extend_to_next_char(span, ',', true);
+    extended.with_hi(extended.hi() + BytePos(1))
+}
+
 /// Converts `expr` to a `char` literal if it's a `str` literal containing a single
 /// character (or a single byte with `ascii_only`)
 pub fn str_literal_to_char_literal(

tests/ui/println_empty_string.fixed

@@ -19,3 +19,42 @@ fn main() {
         //~^ println_empty_string
     }
 }
+
+#[rustfmt::skip]
+fn issue_16167() {
+    println!(  );
+    //~^ println_empty_string
+    match "a" {
+        _ => println!(),
+        //~^ println_empty_string
+    }
+
+    eprintln!();
+    //~^^ println_empty_string
+    match "a" {
+        _ => eprintln!(), // tab
+        //~^ println_empty_string
+    }
+
+    //~v println_empty_string
+    println!(
+        
+    );
+    match "a" {
+        //~v println_empty_string
+        _ => println!(
+            
+        ),
+    }
+
+    //~v println_empty_string
+    eprintln!(
+        
+    );
+    match "a" {
+        //~v println_empty_string
+        _ => eprintln!(
+            
+        ),
+    }
+}

tests/ui/println_empty_string.rs

@@ -19,3 +19,53 @@ fn main() {
         //~^ println_empty_string
     }
 }
+
+#[rustfmt::skip]
+fn issue_16167() {
+    println!("",  );
+    //~^ println_empty_string
+    match "a" {
+        _ => println!(""     ,),
+        //~^ println_empty_string
+    }
+
+    eprintln!(""
+        ,);
+    //~^^ println_empty_string
+    match "a" {
+        _ => eprintln!(""	,), // tab
+        //~^ println_empty_string
+    }
+
+    //~v println_empty_string
+    println!(
+        "\
+                \
+                " /* comment */ ,
+    );
+    match "a" {
+        //~v println_empty_string
+        _ => println!(
+            "\
+                    \
+                    "
+                    // comment
+                    ,
+        ),
+    }
+
+    //~v println_empty_string
+    eprintln!(
+        "\
+                \
+                ",
+    );
+    match "a" {
+        //~v println_empty_string
+        _ => eprintln!(
+            "\
+                    \
+                    ",
+        ),
+    }
+}

tests/ui/println_empty_string.stderr

@@ -33,5 +33,88 @@ 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:25:5
+   |
+LL |     println!("",  );
+   |     ^^^^^^^^^---^^^
+   |              |
+   |              help: remove the empty string
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string.rs:28:14
+   |
+LL |         _ => println!(""     ,),
+   |              ^^^^^^^^^--------^
+   |                       |
+   |                       help: remove the empty string
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:32:5
+   |
+LL |        eprintln!(""
+   |   _____^         -
+   |  |_______________|
+LL | ||         ,);
+   | ||_________-^
+   | |__________|
+   |            help: remove the empty string
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:36:14
+   |
+LL |         _ => eprintln!(""    ,), // tab
+   |              ^^^^^^^^^^-------^
+   |                        |
+   |                        help: remove the empty string
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string.rs:41:5
+   |
+LL | /      println!(
+LL | |/         "\
+LL | ||                 \
+LL | ||                 " /* comment */ ,
+   | ||_________________________________- help: remove the empty string
+LL | |      );
+   | |______^
+
+error: empty string literal in `println!`
+  --> tests/ui/println_empty_string.rs:48:14
+   |
+LL |            _ => println!(
+   |  _______________^
+LL | |/             "\
+LL | ||                     \
+LL | ||                     "
+LL | ||                     // comment
+LL | ||                     ,
+   | ||_____________________- help: remove the empty string
+LL | |          ),
+   | |__________^
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:58:5
+   |
+LL | /      eprintln!(
+LL | |/         "\
+LL | ||                 \
+LL | ||                 ",
+   | ||__________________- help: remove the empty string
+LL | |      );
+   | |______^
+
+error: empty string literal in `eprintln!`
+  --> tests/ui/println_empty_string.rs:65:14
+   |
+LL |            _ => eprintln!(
+   |  _______________^
+LL | |/             "\
+LL | ||                     \
+LL | ||                     ",
+   | ||______________________- help: remove the empty string
+LL | |          ),
+   | |__________^
+
+error: aborting due to 12 previous errors