5 files changed, 475 insertions, 1 deletions

diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
index e4fa9ee36..6fe95da6a 100644
--- a/crates/ra_assists/src/doc_tests/generated.rs
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -726,3 +726,22 @@ use std::{collections::HashMap};
 "#####,
     )
 }
+
+#[test]
+fn doctest_unwrap_block() {
+    check(
+        "unwrap_block",
+        r#####"
+fn foo() {
+    if true {<|>
+        println!("foo");
+    }
+}
+"#####,
+        r#####"
+fn foo() {
+    <|>println!("foo");
+}
+"#####,
+    )
+}
diff --git a/crates/ra_assists/src/handlers/unwrap_block.rs b/crates/ra_assists/src/handlers/unwrap_block.rs
new file mode 100644
index 000000000..b98601f1c
--- /dev/null
+++ b/crates/ra_assists/src/handlers/unwrap_block.rs
@@ -0,0 +1,435 @@
+use crate::{Assist, AssistCtx, AssistId};
+
+use ast::LoopBodyOwner;
+use ra_fmt::unwrap_trivial_block;
+use ra_syntax::{ast, AstNode};
+
+// Assist: unwrap_block
+//
+// Removes the `mut` keyword.
+//
+// ```
+// fn foo() {
+//     if true {<|>
+//         println!("foo");
+//     }
+// }
+// ```
+// ->
+// ```
+// fn foo() {
+//     <|>println!("foo");
+// }
+// ```
+pub(crate) fn unwrap_block(ctx: AssistCtx) -> Option<Assist> {
+    let res = if let Some(if_expr) = ctx.find_node_at_offset::<ast::IfExpr>() {
+        // if expression
+        let mut expr_to_unwrap: Option<ast::Expr> = None;
+        for block_expr in if_expr.blocks() {
+            if let Some(block) = block_expr.block() {
+                let cursor_in_range =
+                    block.l_curly_token()?.text_range().contains_range(ctx.frange.range);
+
+                if cursor_in_range {
+                    let exprto = unwrap_trivial_block(block_expr);
+                    expr_to_unwrap = Some(exprto);
+                    break;
+                }
+            }
+        }
+        let expr_to_unwrap = expr_to_unwrap?;
+        // Find if we are in a else if block
+        let ancestor = ctx
+            .sema
+            .ancestors_with_macros(if_expr.syntax().clone())
+            .skip(1)
+            .find_map(ast::IfExpr::cast);
+
+        if let Some(ancestor) = ancestor {
+            Some((ast::Expr::IfExpr(ancestor), expr_to_unwrap))
+        } else {
+            Some((ast::Expr::IfExpr(if_expr), expr_to_unwrap))
+        }
+    } else if let Some(for_expr) = ctx.find_node_at_offset::<ast::ForExpr>() {
+        // for expression
+        let block_expr = for_expr.loop_body()?;
+        let block = block_expr.block()?;
+        let cursor_in_range = block.l_curly_token()?.text_range().contains_range(ctx.frange.range);
+
+        if cursor_in_range {
+            let expr_to_unwrap = unwrap_trivial_block(block_expr);
+
+            Some((ast::Expr::ForExpr(for_expr), expr_to_unwrap))
+        } else {
+            None
+        }
+    } else if let Some(while_expr) = ctx.find_node_at_offset::<ast::WhileExpr>() {
+        // while expression
+        let block_expr = while_expr.loop_body()?;
+        let block = block_expr.block()?;
+        let cursor_in_range = block.l_curly_token()?.text_range().contains_range(ctx.frange.range);
+
+        if cursor_in_range {
+            let expr_to_unwrap = unwrap_trivial_block(block_expr);
+
+            Some((ast::Expr::WhileExpr(while_expr), expr_to_unwrap))
+        } else {
+            None
+        }
+    } else if let Some(loop_expr) = ctx.find_node_at_offset::<ast::LoopExpr>() {
+        // loop expression
+        let block_expr = loop_expr.loop_body()?;
+        let block = block_expr.block()?;
+        let cursor_in_range = block.l_curly_token()?.text_range().contains_range(ctx.frange.range);
+
+        if cursor_in_range {
+            let expr_to_unwrap = unwrap_trivial_block(block_expr);
+
+            Some((ast::Expr::LoopExpr(loop_expr), expr_to_unwrap))
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
+    let (expr, expr_to_unwrap) = res?;
+    ctx.add_assist(AssistId("unwrap_block"), "Unwrap block", |edit| {
+        edit.set_cursor(expr.syntax().text_range().start());
+        edit.target(expr_to_unwrap.syntax().text_range());
+
+        let pat_start: &[_] = &[' ', '{', '\n'];
+        let expr_to_unwrap = expr_to_unwrap.to_string();
+        let expr_string = expr_to_unwrap.trim_start_matches(pat_start);
+        let mut expr_string_lines: Vec<&str> = expr_string.lines().collect();
+        expr_string_lines.pop(); // Delete last line
+
+        let expr_string = expr_string_lines
+            .into_iter()
+            .map(|line| line.replacen("    ", "", 1)) // Delete indentation
+            .collect::<Vec<String>>()
+            .join("\n");
+
+        edit.replace(expr.syntax().text_range(), expr_string);
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::helpers::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn simple_if() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                bar();
+                if true {<|>
+                    foo();
+
+                    //comment
+                    bar();
+                } else {
+                    println!("bar");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                bar();
+                <|>foo();
+
+                //comment
+                bar();
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_else() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                bar();
+                if true {
+                    foo();
+
+                    //comment
+                    bar();
+                } else {<|>
+                    println!("bar");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                bar();
+                <|>println!("bar");
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_else_if() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {<|>
+                    println!("bar");
+                } else {
+                    println!("foo");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                //bar();
+                <|>println!("bar");
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_bad_cursor_position() {
+        check_assist_not_applicable(
+            unwrap_block,
+            r#"
+            fn main() {
+                bar();<|>
+                if true {
+                    foo();
+
+                    //comment
+                    bar();
+                } else {
+                    println!("bar");
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn issue_example_with_if() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &Type) {
+                if let Some(ty) = &ctx.expected_type {<|>
+                    if let Some(Adt::Enum(enum_data)) = ty.as_adt() {
+                        let variants = enum_data.variants(ctx.db);
+
+                        let module = if let Some(module) = ctx.scope().module() {
+                            // Compute path from the completion site if available.
+                            module
+                        } else {
+                            // Otherwise fall back to the enum's definition site.
+                            enum_data.module(ctx.db)
+                        };
+
+                        for variant in variants {
+                            if let Some(path) = module.find_use_path(ctx.db, ModuleDef::from(variant)) {
+                                // Variants with trivial paths are already added by the existing completion logic,
+                                // so we should avoid adding these twice
+                                if path.segments.len() > 1 {
+                                    acc.add_enum_variant(ctx, variant, Some(path.to_string()));
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &Type) {
+                <|>if let Some(Adt::Enum(enum_data)) = ty.as_adt() {
+                    let variants = enum_data.variants(ctx.db);
+
+                    let module = if let Some(module) = ctx.scope().module() {
+                        // Compute path from the completion site if available.
+                        module
+                    } else {
+                        // Otherwise fall back to the enum's definition site.
+                        enum_data.module(ctx.db)
+                    };
+
+                    for variant in variants {
+                        if let Some(path) = module.find_use_path(ctx.db, ModuleDef::from(variant)) {
+                            // Variants with trivial paths are already added by the existing completion logic,
+                            // so we should avoid adding these twice
+                            if path.segments.len() > 1 {
+                                acc.add_enum_variant(ctx, variant, Some(path.to_string()));
+                            }
+                        }
+                    }
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_for() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                for i in 0..5 {<|>
+                    if true {
+                        foo();
+
+                        //comment
+                        bar();
+                    } else {
+                        println!("bar");
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                <|>if true {
+                    foo();
+
+                    //comment
+                    bar();
+                } else {
+                    println!("bar");
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_in_for() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                for i in 0..5 {
+                    if true {<|>
+                        foo();
+
+                        //comment
+                        bar();
+                    } else {
+                        println!("bar");
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                for i in 0..5 {
+                    <|>foo();
+
+                    //comment
+                    bar();
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_loop() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                loop {<|>
+                    if true {
+                        foo();
+
+                        //comment
+                        bar();
+                    } else {
+                        println!("bar");
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                <|>if true {
+                    foo();
+
+                    //comment
+                    bar();
+                } else {
+                    println!("bar");
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_while() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                while true {<|>
+                    if true {
+                        foo();
+
+                        //comment
+                        bar();
+                    } else {
+                        println!("bar");
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                <|>if true {
+                    foo();
+
+                    //comment
+                    bar();
+                } else {
+                    println!("bar");
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_in_while_bad_cursor_position() {
+        check_assist_not_applicable(
+            unwrap_block,
+            r#"
+            fn main() {
+                while true {
+                    if true {
+                        foo();<|>
+
+                        //comment
+                        bar();
+                    } else {
+                        println!("bar");
+                    }
+                }
+            }
+            "#,
+        );
+    }
+}
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 64bd87afb..c5df86600 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -143,6 +143,7 @@ mod handlers {
     mod split_import;
     mod add_from_impl_for_enum;
     mod reorder_fields;
+    mod unwrap_block;
 
     pub(crate) fn all() -> &'static [AssistHandler] {
         &[
@@ -181,6 +182,7 @@ mod handlers {
             replace_unwrap_with_match::replace_unwrap_with_match,
             split_import::split_import,
             add_from_impl_for_enum::add_from_impl_for_enum,
+            unwrap_block::unwrap_block,
             // These are manually sorted for better priorities
             add_missing_impl_members::add_missing_impl_members,
             add_missing_impl_members::add_missing_default_members,
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 93aa3d45f..1c1134bc5 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -43,7 +43,7 @@ impl ast::IfExpr {
         Some(res)
     }
 
-    fn blocks(&self) -> AstChildren<ast::BlockExpr> {
+    pub fn blocks(&self) -> AstChildren<ast::BlockExpr> {
         support::children(self.syntax())
     }
 }
diff --git a/docs/user/assists.md b/docs/user/assists.md
index 6c6943622..02323772c 100644
--- a/docs/user/assists.md
+++ b/docs/user/assists.md
@@ -695,3 +695,21 @@ use std::┃collections::HashMap;
 // AFTER
 use std::{collections::HashMap};
 ```
+
+## `unwrap_block`
+
+Removes the `mut` keyword.
+
+```rust
+// BEFORE
+fn foo() {
+    if true {┃
+        println!("foo");
+    }
+}
+
+// AFTER
+fn foo() {
+    ┃println!("foo");
+}
+```