Indentation of multi post-comments to a list item

src/formatting/lists.rs

@@ -8,7 +8,7 @@ use unicode_segmentation::UnicodeSegmentation;
 
 use crate::config::{lists::*, Config, IndentStyle};
 use crate::formatting::{
-    comment::{find_comment_end, rewrite_comment, FindUncommented},
+    comment::{comment_style, find_comment_end, rewrite_comment, FindUncommented},
     rewrite::RewriteContext,
     shape::{Indent, Shape},
     utils::{
@@ -421,6 +421,33 @@ where
             result.push_str(formatting.separator);
         }
 
+        // Note about post-comments indentation:
+        // In the original code the the item separator may follow some comments that
+        // may span over some lines.  E.g.:
+        //     item1 /* 1st comment line 1
+        //            * line 2 */
+        //           /* 2nd comment */,
+        //     item2,
+        //
+        // In this case, rustfmt moves the separator right after the item:
+        //     item1, /* 1st comment line 1
+        //             * line 2 */
+        //            /* 2nd comment */
+        //     item2,
+        //
+        // In this code, only the 1st comment is regarded as post comment of item1.
+        // 2nd comment is regarded as pre-comment of item2, therefore the output
+        // of another round of formatting this code is:
+        //     item1, /* 1st comment line 1
+        //             * line 2 */
+        //     /* 2nd comment */
+        //     item2,
+        //
+        // i.e. 2nd comment is now indented as pre-comment.
+        //
+        // This why in the code below a first multiline post-comment is indented
+        // differently then the other post-comments.
+
         if tactic != DefinitiveListTactic::Horizontal && item.post_comment.is_some() {
             let comment = item.post_comment.as_ref().unwrap();
             let overhead = last_line_width(&result) + first_line_width(comment.trim());
@@ -444,19 +471,88 @@ where
                 };
                 let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
                 let offset = formatting.shape.indent + overhead;
-                let comment_shape = Shape::legacy(width, offset);
-
-                // Use block-style only for the last item or multiline comments.
-                let block_style = !formatting.ends_with_newline && last
-                    || comment.trim().contains('\n')
-                    || comment.trim().len() > width;
-
-                rewrite_comment(
-                    comment.trim_start(),
-                    block_style,
-                    comment_shape,
-                    formatting.config,
-                )
+                let comment_start_trimmed = comment.trim_start();
+
+                // Find if first comment is single line and the end of the first comment
+                // when it is a multi-line block comment (since the first post-comment
+                // is added to the same line of the list item, its indentation is important
+                // only when it is a multiline comment).
+                let style = comment_style(
+                    comment_start_trimmed,
+                    formatting.config.normalize_comments(),
+                );
+                let (first_comment_single_line, first_comment_end) =
+                    if !formatting.config.normalize_comments() && style.is_line_comment() {
+                        // Line comment (not normalizaed)
+                        (true, None)
+                    } else if style.is_block_comment() {
+                        match find_comment_end(&comment_start_trimmed) {
+                            Some(i) => {
+                                if comment_start_trimmed[..i].contains('\n') {
+                                    // Multiline-comment (may be because of normalization)
+                                    (false, Some(i))
+                                } else {
+                                    // One line coment (Block or normalizaed Line)
+                                    (true, None)
+                                }
+                            }
+                            _ => (false, None), // Unknow comment end
+                        }
+                    } else {
+                        (false, None) // Unexpected case - non-block comment with normalization
+                    };
+
+                // Closure for formatting post-comment with specific Shape
+                let rewrite_post_comment_with_shape = |cmt: &str, shape: Shape| {
+                    // Use block-style only for the last item or multiline comments.
+                    let block_style = !formatting.ends_with_newline && last
+                        || cmt.trim().contains('\n')
+                        || cmt.trim().len() > width;
+                    rewrite_comment(&cmt, block_style, shape, formatting.config)
+                };
+
+                // Properly indent first and other comments
+                match (first_comment_single_line, first_comment_end) {
+                    (_, None) => {
+                        // First comment not multiline - same indentation for all comments
+                        let comment_shape =
+                            if first_comment_single_line && comment_start_trimmed.contains("\n") {
+                                formatting.shape
+                            } else {
+                                Shape::legacy(width, offset)
+                            };
+                        rewrite_post_comment_with_shape(comment_start_trimmed, comment_shape)
+                    }
+                    (false, Some(comment_end)) => {
+                        // Separate indentation for first multi-line block comment
+                        let formatted_first_comment = rewrite_comment(
+                            &comment_start_trimmed[..comment_end],
+                            true,
+                            Shape::legacy(width, offset),
+                            formatting.config,
+                        )?;
+                        let second_comment_start = comment_start_trimmed[comment_end..]
+                            .find(|c: char| !c.is_whitespace())
+                            .map_or(None, |i| Some(i + comment_end));
+                        let formatted_all_comments = match second_comment_start {
+                            Some(i) => {
+                                let second_comment = comment_start_trimmed[i..].to_string();
+                                let formatted = rewrite_post_comment_with_shape(
+                                    &second_comment,
+                                    formatting.shape,
+                                )?;
+                                let indent = formatting
+                                    .shape
+                                    .indent
+                                    .to_string_with_newline(formatting.config);
+                                format!("{}{}{}", formatted_first_comment, indent, formatted)
+                            }
+                            _ => formatted_first_comment,
+                        };
+                        Some(formatted_all_comments)
+                    }
+                    (_, _) => unreachable!(),
+                }
             };
 
             let mut formatted_comment = rewrite_post_comment(&mut item_max_width)?;
@@ -699,6 +795,11 @@ pub(crate) fn get_comment_end(
                 find_comment_end(&post_snippet[i..]).unwrap() + i,
                 separator_index + 1,
             ),
+            // Comment is preceeded by new line and followed by a separator.
+            (Some(i), Some(_)) if separator_index > i => cmp::max(
+                find_comment_end(&post_snippet[i..]).unwrap() + i,
+                separator_index + 1,
+            ),
             // Potential *single* line comment.
             (_, Some(j)) if j > separator_index => j + 1,
             _ => post_snippet.len(),

tests/source/issue-3847.rs

@@ -0,0 +1,205 @@
+// Tests for multi one-line post-comments of list item
+// (related cases when `normalize_comments` is set are already included in other test files).
+
+// Original cases from issue #3847
+type T1 = Result<
+    u32 // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        // diam ac cursus. Aliquam condimentum in erat quis pretium.
+        // accumsan urna. Cras volutpat sit amet quam.
+        ,
+    bool,
+>;
+type T2 = Result<
+    u32, // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+         // diam ac cursus. Aliquam condimentum in erat quis pretium.
+         // accumsan urna. Cras volutpat sit amet quam.
+    bool,
+>;
+
+// Additional test cases with lists
+fn main() {
+	let a = ["GOOD"        // Comment1
+	                       // Comment2
+				   ,
+				   ];
+	let b = ["WASBAD"        // Comment1
+	                       // Comment2
+						   ,
+				   "CCC",
+				   ];
+}
+
+// Tests with one multi-line block comment
+type T3_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */
+		 ,
+    bool,
+>;
+type T4_good = Result<
+    u32, /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */
+    bool,
+>;
+
+fn main() {
+	let a = ["WASGOOD1"              /* Comment1
+	                         * Comment2 */
+				   ,
+			"WASGOOD2",               /* Comment1
+			                * Comment2 */
+			"CCC",
+			];
+}
+
+// Tests with one-line block-comments
+type T5_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+        /* diam ac cursus. Aliquam condimentum in erat quis pretium. */
+        /* accumsan urna. Cras volutpat sit amet quam. */
+		 ,
+    bool,
+>;
+type T6_good = Result<
+    u32, /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+        /* diam ac cursus. Aliquam condimentum in erat quis pretium. */
+        /* accumsan urna. Cras volutpat sit amet quam. */
+    bool,
+>;
+
+// Tests with mix one-line and multi-linecomments - one-line is first
+type T8_good = Result<
+    u32 // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */,
+    bool,
+>;
+type T9_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+        /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */
+        // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        ,
+        bool,
+>;
+type T9_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */,
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    bool,
+>;
+
+// Tests with mix one-line and multi-linecomments - multi-line is first
+type T10_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */
+        // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        ,
+    bool,
+>;
+type T11_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        * diam ac cursus. Aliquam condimentum in erat quis pretium.
+        * accumsan urna. Cras volutpat sit amet quam. */
+        /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */,
+        // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+        bool,
+>;
+type T12_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    ,
+    bool,
+>;
+type T12_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */,
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    bool,
+>;
+type T13_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. */    /*Cras volutpat sit amet quam. */
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    ,
+    bool,
+>;
+
+// Tests with mix one-line and multi-linecomments -
+// multi-line is first with newline between comments
+type T14_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */
+
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */,
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    bool,
+>;
+type T15_good = Result<
+    u32 /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */
+
+
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    ,
+    bool,
+>;
+
+// Tests with first comment is not in same line of item
+type T16_good = Result<
+    u32 
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    /* diam ac cursus. Aliquam condimentum in erat quis pretium. */
+    /* accumsan urna. Cras volutpat sit amet quam. */,
+    bool,
+>;
+type T17_good = Result<
+u32 
+/* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+/* diam ac cursus. Aliquam condimentum in erat quis pretium. */
+/* accumsan urna. Cras volutpat sit amet quam. */
+,
+bool,
+>;
+type T18_good = Result<
+    u32 
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    /* diam ac cursus. Aliquam condimentum in erat quis pretium. */,
+    /* accumsan urna. Cras volutpat sit amet quam. */
+    bool,
+>;
+type T19_good = Result<
+    u32
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */,
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    bool,
+>;
+type T20_good = Result<
+    u32
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    * diam ac cursus. Aliquam condimentum in erat quis pretium.
+    * accumsan urna. Cras volutpat sit amet quam. */
+    /* Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam */,
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam
+    bool,
+>;