Merge #8207

8207: Show dbg remove assist on empty contents r=edwin0cheng a=ivan770

Closes #8185

Co-authored-by: ivan770 <leshenko.ivan770@gmail.com>
Co-authored-by: ivan770 <ivan@ivan770.me>

crates/ide_assists/src/handlers/remove_dbg.rs

@@ -1,5 +1,5 @@
 use syntax::{
-    ast::{self, AstNode},
+    ast::{self, AstNode, AstToken},
     match_ast, SyntaxElement, TextRange, TextSize, T,
 };
 
@@ -24,7 +24,39 @@ pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let macro_call = ctx.find_node_at_offset::<ast::MacroCall>()?;
     let new_contents = adjusted_macro_contents(&macro_call)?;
 
-    let macro_text_range = macro_call.syntax().text_range();
+    let parent = macro_call.syntax().parent();
+
+    let macro_text_range = if let Some(it) = parent.as_ref() {
+        if new_contents.is_empty() {
+            match_ast! {
+                match it {
+                    ast::BlockExpr(it) => {
+                        macro_call.syntax()
+                            .prev_sibling_or_token()
+                            .and_then(whitespace_start)
+                            .map(|start| TextRange::new(start, macro_call.syntax().text_range().end()))
+                            .unwrap_or(macro_call.syntax().text_range())
+                    },
+                    ast::ExprStmt(it) => {
+                        let start = it
+                            .syntax()
+                            .prev_sibling_or_token()
+                            .and_then(whitespace_start)
+                            .unwrap_or(it.syntax().text_range().start());
+                        let end = it.syntax().text_range().end();
+
+                        TextRange::new(start, end)
+                    },
+                    _ => macro_call.syntax().text_range()
+                }
+            }
+        } else {
+            macro_call.syntax().text_range()
+        }
+    } else {
+        macro_call.syntax().text_range()
+    };
+
     let macro_end = if macro_call.semicolon_token().is_some() {
         macro_text_range.end() - TextSize::of(';')
     } else {
@@ -36,11 +68,22 @@ pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
         "Remove dbg!()",
         macro_text_range,
         |builder| {
-            builder.replace(TextRange::new(macro_text_range.start(), macro_end), new_contents);
+            builder.replace(
+                TextRange::new(macro_text_range.start(), macro_end),
+                if new_contents.is_empty() && parent.and_then(ast::LetStmt::cast).is_some() {
+                    ast::make::expr_unit().to_string()
+                } else {
+                    new_contents
+                },
+            );
         },
     )
 }
 
+fn whitespace_start(it: SyntaxElement) -> Option<TextSize> {
+    Some(it.into_token().and_then(ast::Whitespace::cast)?.syntax().text_range().start())
+}
+
 fn adjusted_macro_contents(macro_call: &ast::MacroCall) -> Option<String> {
     let contents = get_valid_macrocall_contents(&macro_call, "dbg")?;
     let macro_text_with_brackets = macro_call.token_tree()?.syntax().text();
@@ -94,16 +137,12 @@ fn get_valid_macrocall_contents(
     let mut contents_between_brackets = children_with_tokens.collect::<Vec<_>>();
     let last_child = contents_between_brackets.pop()?;
 
-    if contents_between_brackets.is_empty() {
-        None
-    } else {
     match (first_child.kind(), last_child.kind()) {
         (T!['('], T![')']) | (T!['['], T![']']) | (T!['{'], T!['}']) => {
             Some(contents_between_brackets)
         }
         _ => None,
     }
-    }
 }
 
 fn needs_parentheses_around_macro_contents(macro_contents: Vec<SyntaxElement>) -> bool {
@@ -415,6 +454,50 @@ fn main() {
 }"#,
             r#"fn foo() {
     match &x {}
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_remove_empty_dbg() {
+        check_assist(remove_dbg, r#"fn foo() { $0dbg!(); }"#, r#"fn foo() { }"#);
+        check_assist(
+            remove_dbg,
+            r#"
+fn foo() {
+    $0dbg!();
+}
+"#,
+            r#"
+fn foo() {
+}
+"#,
+        );
+        check_assist(
+            remove_dbg,
+            r#"
+fn foo() {
+    let test = $0dbg!();
+}"#,
+            r#"
+fn foo() {
+    let test = ();
+}"#,
+        );
+        check_assist(
+            remove_dbg,
+            r#"
+fn foo() {
+    let t = {
+        println!("Hello, world");
+        $0dbg!()
+    };
+}"#,
+            r#"
+fn foo() {
+    let t = {
+        println!("Hello, world");
+    };
 }"#,
         );
     }