11 files changed, 857 insertions, 116 deletions

diff --git a/Cargo.lock b/Cargo.lock
index a6038d36a..dbd7a746e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -13,9 +13,9 @@ dependencies = [
 
 [[package]]
 name = "adler"
-version = "0.2.3"
+version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ee2a4ec343196209d6594e19543ae87a39f96d5534d7174822a3ad825dd6ed7e"
+checksum = "bedc89c5c7b5550ffb9372eb5c5ffc7f9f705cc3f4a128bd4669b9745f555093"
 
 [[package]]
 name = "always-assert"
@@ -273,28 +273,26 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.2"
+version = "0.9.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d60ab4a8dba064f2fbb5aa270c28da5cf4bbd0e72dae1140a6b0353a779dbe00"
+checksum = "2584f639eb95fea8c798496315b297cf81b9b58b6d30ab066a75455333cf4b12"
 dependencies = [
  "cfg-if",
  "crossbeam-utils",
  "lazy_static",
- "loom",
  "memoffset",
  "scopeguard",
 ]
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.2"
+version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bae8f328835f8f5a6ceb6a7842a7f2d0c03692adb5c889347235d59194731fe3"
+checksum = "e7e9d99fa91428effe99c5c6d4634cdeba32b8cf784fc428a2a687f61a952c49"
 dependencies = [
  "autocfg",
  "cfg-if",
  "lazy_static",
- "loom",
 ]
 
 [[package]]
@@ -438,19 +436,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d79238883cf0307100b90aba4a755d8051a3182305dfe7f649a1e9dc0517006f"
 
 [[package]]
-name = "generator"
-version = "0.6.24"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9fed24fd1e18827652b4d55652899a1e9da8e54d91624dc3437a5bc3a9f9a9c"
-dependencies = [
- "cc",
- "libc",
- "log",
- "rustversion",
- "winapi",
-]
-
-[[package]]
 name = "gimli"
 version = "0.23.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -845,17 +830,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "loom"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d44c73b4636e497b4917eb21c33539efa3816741a2d3ff26c6316f1b529481a4"
-dependencies = [
- "cfg-if",
- "generator",
- "scoped-tls",
-]
-
-[[package]]
 name = "lsp-server"
 version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -944,9 +918,9 @@ dependencies = [
 
 [[package]]
 name = "miniz_oxide"
-version = "0.4.3"
+version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0f2d26ec3309788e423cfbf68ad1800f061638098d76a83681af979dc4eda19d"
+checksum = "a92518e98c078586bc6c934028adcca4c92a53d6a958196de835170a01d84e4b"
 dependencies = [
  "adler",
  "autocfg",
@@ -1040,9 +1014,9 @@ checksum = "a9a7ab5d64814df0fe4a4b5ead45ed6c5f181ee3ff04ba344313a6c80446c5d4"
 
 [[package]]
 name = "once_cell"
-version = "1.6.0"
+version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ad167a2f54e832b82dbe003a046280dceffe5227b5f79e08e363a29638cfddd"
+checksum = "10acf907b94fc1b1a152d08ef97e7759650268cf986bf127f387e602b02c7e5a"
 
 [[package]]
 name = "oorandom"
@@ -1400,9 +1374,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-ap-rustc_lexer"
-version = "707.0.0"
+version = "708.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e27206aceb3b2153a3c367727d534362a1ce63a43ece8fd878195738a83aaf6f"
+checksum = "2706fc7106c75eaea49efe9f35f719a6fdfdb95212122ec2b543659406bae7ea"
 dependencies = [
  "unicode-xid",
 ]
@@ -1420,12 +1394,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
 [[package]]
-name = "rustversion"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb5d2a036dc6d2d8fd16fde3498b04306e29bd193bf306a57427019b823d5acd"
-
-[[package]]
 name = "ryu"
 version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1717,9 +1685,9 @@ dependencies = [
 
 [[package]]
 name = "tracing"
-version = "0.1.24"
+version = "0.1.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f77d3842f76ca899ff2dbcf231c5c65813dea431301d6eb686279c15c4464f12"
+checksum = "01ebdc2bb4498ab1ab5f5b73c5803825e60199229ccba0698170e3be0e7f959f"
 dependencies = [
  "cfg-if",
  "pin-project-lite",
diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
index c7609e90d..c94fb580a 100644
--- a/crates/hir_expand/src/name.rs
+++ b/crates/hir_expand/src/name.rs
@@ -189,6 +189,7 @@ pub mod known {
         // Components of known path (function name)
         filter_map,
         next,
+        iter_mut,
         // Builtin macros
         file,
         column,
diff --git a/crates/ide_assists/src/handlers/auto_import.rs b/crates/ide_assists/src/handlers/auto_import.rs
index e93901cb3..dc38f90e9 100644
--- a/crates/ide_assists/src/handlers/auto_import.rs
+++ b/crates/ide_assists/src/handlers/auto_import.rs
@@ -33,9 +33,9 @@ use crate::{AssistContext, AssistId, AssistKind, Assists, GroupLabel};
 // use super::AssistContext;
 // ```
 //
-// .Merge Behaviour
+// .Merge Behavior
 //
-// It is possible to configure how use-trees are merged with the `importMergeBehaviour` setting.
+// It is possible to configure how use-trees are merged with the `importMergeBehavior` setting.
 // It has the following configurations:
 //
 // - `full`: This setting will cause auto-import to always completely merge use-trees that share the
@@ -46,7 +46,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists, GroupLabel};
 // - `none`: This setting will cause auto-import to never merge use-trees keeping them as simple
 //  paths.
 //
-// In `VS Code` the configuration for this is `rust-analyzer.assist.importMergeBehaviour`.
+// In `VS Code` the configuration for this is `rust-analyzer.assist.importMergeBehavior`.
 //
 // .Import Prefix
 //
diff --git a/crates/ide_assists/src/handlers/convert_for_to_iter_for_each.rs b/crates/ide_assists/src/handlers/convert_for_to_iter_for_each.rs
new file mode 100644
index 000000000..9fddf889c
--- /dev/null
+++ b/crates/ide_assists/src/handlers/convert_for_to_iter_for_each.rs
@@ -0,0 +1,301 @@
+use ast::LoopBodyOwner;
+use hir::known;
+use ide_db::helpers::FamousDefs;
+use stdx::format_to;
+use syntax::{ast, AstNode};
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: convert_for_to_iter_for_each
+//
+// Converts a for loop into a for_each loop on the Iterator.
+//
+// ```
+// fn main() {
+//     let x = vec![1, 2, 3];
+//     for $0v in x {
+//         let y = v * 2;
+//     }
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let x = vec![1, 2, 3];
+//     x.into_iter().for_each(|v| {
+//         let y = v * 2;
+//     });
+// }
+// ```
+pub(crate) fn convert_for_to_iter_for_each(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let for_loop = ctx.find_node_at_offset::<ast::ForExpr>()?;
+    let iterable = for_loop.iterable()?;
+    let pat = for_loop.pat()?;
+    let body = for_loop.loop_body()?;
+
+    acc.add(
+        AssistId("convert_for_to_iter_for_each", AssistKind::RefactorRewrite),
+        "Convert a for loop into an Iterator::for_each",
+        for_loop.syntax().text_range(),
+        |builder| {
+            let mut buf = String::new();
+
+            if let Some((expr_behind_ref, method)) =
+                is_ref_and_impls_iter_method(&ctx.sema, &iterable)
+            {
+                // We have either "for x in &col" and col implements a method called iter
+                //             or "for x in &mut col" and col implements a method called iter_mut
+                format_to!(buf, "{}.{}()", expr_behind_ref, method);
+            } else if impls_core_iter(&ctx.sema, &iterable) {
+                format_to!(buf, "{}", iterable);
+            } else {
+                if let ast::Expr::RefExpr(_) = iterable {
+                    format_to!(buf, "({}).into_iter()", iterable);
+                } else {
+                    format_to!(buf, "{}.into_iter()", iterable);
+                }
+            }
+
+            format_to!(buf, ".for_each(|{}| {});", pat, body);
+
+            builder.replace(for_loop.syntax().text_range(), buf)
+        },
+    )
+}
+
+/// If iterable is a reference where the expression behind the reference implements a method
+/// returning an Iterator called iter or iter_mut (depending on the type of reference) then return
+/// the expression behind the reference and the method name
+fn is_ref_and_impls_iter_method(
+    sema: &hir::Semantics<ide_db::RootDatabase>,
+    iterable: &ast::Expr,
+) -> Option<(ast::Expr, hir::Name)> {
+    let ref_expr = match iterable {
+        ast::Expr::RefExpr(r) => r,
+        _ => return None,
+    };
+    let wanted_method = if ref_expr.mut_token().is_some() { known::iter_mut } else { known::iter };
+    let expr_behind_ref = ref_expr.expr()?;
+    let typ = sema.type_of_expr(&expr_behind_ref)?;
+    let scope = sema.scope(iterable.syntax());
+    let krate = scope.module()?.krate();
+    let traits_in_scope = scope.traits_in_scope();
+    let iter_trait = FamousDefs(sema, Some(krate)).core_iter_Iterator()?;
+    let has_wanted_method = typ.iterate_method_candidates(
+        sema.db,
+        krate,
+        &traits_in_scope,
+        Some(&wanted_method),
+        |_, func| {
+            if func.ret_type(sema.db).impls_trait(sema.db, iter_trait, &[]) {
+                return Some(());
+            }
+            None
+        },
+    );
+    has_wanted_method.and(Some((expr_behind_ref, wanted_method)))
+}
+
+/// Whether iterable implements core::Iterator
+fn impls_core_iter(sema: &hir::Semantics<ide_db::RootDatabase>, iterable: &ast::Expr) -> bool {
+    let it_typ = if let Some(i) = sema.type_of_expr(iterable) {
+        i
+    } else {
+        return false;
+    };
+    let module = if let Some(m) = sema.scope(iterable.syntax()).module() {
+        m
+    } else {
+        return false;
+    };
+    let krate = module.krate();
+    if let Some(iter_trait) = FamousDefs(sema, Some(krate)).core_iter_Iterator() {
+        return it_typ.impls_trait(sema.db, iter_trait, &[]);
+    }
+    false
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    const EMPTY_ITER_FIXTURE: &'static str = r"
+//- /lib.rs deps:core crate:empty_iter
+pub struct EmptyIter;
+impl Iterator for EmptyIter {
+    type Item = usize;
+    fn next(&mut self) -> Option<Self::Item> { None }
+}
+
+pub struct Empty;
+impl Empty {
+    pub fn iter(&self) -> EmptyIter { EmptyIter }
+    pub fn iter_mut(&self) -> EmptyIter { EmptyIter }
+}
+
+pub struct NoIterMethod;
+";
+
+    fn check_assist_with_fixtures(before: &str, after: &str) {
+        let before = &format!(
+            "//- /main.rs crate:main deps:core,empty_iter{}{}{}",
+            before,
+            FamousDefs::FIXTURE,
+            EMPTY_ITER_FIXTURE
+        );
+        check_assist(convert_for_to_iter_for_each, before, after);
+    }
+
+    #[test]
+    fn test_not_for() {
+        check_assist_not_applicable(
+            convert_for_to_iter_for_each,
+            r"
+let mut x = vec![1, 2, 3];
+x.iter_mut().$0for_each(|v| *v *= 2);
+        ",
+        )
+    }
+
+    #[test]
+    fn test_simple_for() {
+        check_assist(
+            convert_for_to_iter_for_each,
+            r"
+fn main() {
+    let x = vec![1, 2, 3];
+    for $0v in x {
+        v *= 2;
+    }
+}",
+            r"
+fn main() {
+    let x = vec![1, 2, 3];
+    x.into_iter().for_each(|v| {
+        v *= 2;
+    });
+}",
+        )
+    }
+
+    #[test]
+    fn test_for_borrowed() {
+        check_assist_with_fixtures(
+            r"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    for $0v in &x {
+        let a = v * 2;
+    }
+}
+",
+            r"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    x.iter().for_each(|v| {
+        let a = v * 2;
+    });
+}
+",
+        )
+    }
+
+    #[test]
+    fn test_for_borrowed_no_iter_method() {
+        check_assist_with_fixtures(
+            r"
+use empty_iter::*;
+fn main() {
+    let x = NoIterMethod;
+    for $0v in &x {
+        let a = v * 2;
+    }
+}
+",
+            r"
+use empty_iter::*;
+fn main() {
+    let x = NoIterMethod;
+    (&x).into_iter().for_each(|v| {
+        let a = v * 2;
+    });
+}
+",
+        )
+    }
+
+    #[test]
+    fn test_for_borrowed_mut() {
+        check_assist_with_fixtures(
+            r"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    for $0v in &mut x {
+        let a = v * 2;
+    }
+}
+",
+            r"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    x.iter_mut().for_each(|v| {
+        let a = v * 2;
+    });
+}
+",
+        )
+    }
+
+    #[test]
+    fn test_for_borrowed_mut_behind_var() {
+        check_assist(
+            convert_for_to_iter_for_each,
+            r"
+fn main() {
+    let x = vec![1, 2, 3];
+    let y = &mut x;
+    for $0v in y {
+        *v *= 2;
+    }
+}",
+            r"
+fn main() {
+    let x = vec![1, 2, 3];
+    let y = &mut x;
+    y.into_iter().for_each(|v| {
+        *v *= 2;
+    });
+}",
+        )
+    }
+
+    #[test]
+    fn test_already_impls_iterator() {
+        check_assist_with_fixtures(
+            r#"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    for$0 a in x.iter().take(1) {
+        println!("{}", a);
+    }
+}
+"#,
+            r#"
+use empty_iter::*;
+fn main() {
+    let x = Empty;
+    x.iter().take(1).for_each(|a| {
+        println!("{}", a);
+    });
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide_assists/src/handlers/flip_comma.rs b/crates/ide_assists/src/handlers/flip_comma.rs
index 18cf64a34..7f5e75d34 100644
--- a/crates/ide_assists/src/handlers/flip_comma.rs
+++ b/crates/ide_assists/src/handlers/flip_comma.rs
@@ -1,4 +1,4 @@
-use syntax::{algo::non_trivia_sibling, Direction, T};
+use syntax::{algo::non_trivia_sibling, Direction, SyntaxKind, T};
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 
@@ -28,6 +28,12 @@ pub(crate) fn flip_comma(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
         return None;
     }
 
+    // Don't apply a "flip" inside the macro call
+    // since macro input are just mere tokens
+    if comma.ancestors().any(|it| it.kind() == SyntaxKind::MACRO_CALL) {
+        return None;
+    }
+
     acc.add(
         AssistId("flip_comma", AssistKind::RefactorRewrite),
         "Flip comma",
@@ -43,7 +49,7 @@ pub(crate) fn flip_comma(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
 mod tests {
     use super::*;
 
-    use crate::tests::{check_assist, check_assist_target};
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn flip_comma_works_for_function_parameters() {
@@ -81,4 +87,20 @@ mod tests {
             ",",
         );
     }
+
+    #[test]
+    fn flip_comma_works() {
+        check_assist(
+            flip_comma,
+            r#"fn main() {((1, 2),$0 (3, 4));}"#,
+            r#"fn main() {((3, 4), (1, 2));}"#,
+        )
+    }
+
+    #[test]
+    fn flip_comma_not_applicable_for_macro_input() {
+        // "Flip comma" assist shouldn't be applicable inside the macro call
+        // See https://github.com/rust-analyzer/rust-analyzer/issues/7693
+        check_assist_not_applicable(flip_comma, r#"bar!(a,$0 b)"#);
+    }
 }
diff --git a/crates/ide_assists/src/handlers/generate_enum_match_method.rs b/crates/ide_assists/src/handlers/generate_enum_is_method.rs
index aeb887e71..7e181a480 100644
--- a/crates/ide_assists/src/handlers/generate_enum_match_method.rs
+++ b/crates/ide_assists/src/handlers/generate_enum_is_method.rs
@@ -1,14 +1,13 @@
-use stdx::{format_to, to_lower_snake_case};
+use stdx::to_lower_snake_case;
 use syntax::ast::VisibilityOwner;
 use syntax::ast::{self, AstNode, NameOwner};
-use test_utils::mark;
 
 use crate::{
-    utils::{find_impl_block_end, find_struct_impl, generate_impl_text},
+    utils::{add_method_to_adt, find_struct_impl},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
-// Assist: generate_enum_match_method
+// Assist: generate_enum_is_method
 //
 // Generate an `is_` method for an enum variant.
 //
@@ -34,79 +33,52 @@ use crate::{
 //     }
 // }
 // ```
-pub(crate) fn generate_enum_match_method(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+pub(crate) fn generate_enum_is_method(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let variant = ctx.find_node_at_offset::<ast::Variant>()?;
     let variant_name = variant.name()?;
-    let parent_enum = variant.parent_enum();
-    if !matches!(variant.kind(), ast::StructKind::Unit) {
-        mark::hit!(test_gen_enum_match_on_non_unit_variant_not_implemented);
-        return None;
-    }
+    let parent_enum = ast::Adt::Enum(variant.parent_enum());
+    let pattern_suffix = match variant.kind() {
+        ast::StructKind::Record(_) => " { .. }",
+        ast::StructKind::Tuple(_) => "(..)",
+        ast::StructKind::Unit => "",
+    };
 
     let enum_lowercase_name = to_lower_snake_case(&parent_enum.name()?.to_string());
-    let fn_name = to_lower_snake_case(&variant_name.to_string());
+    let fn_name = format!("is_{}", &to_lower_snake_case(variant_name.text()));
 
     // Return early if we've found an existing new fn
-    let impl_def = find_struct_impl(
-        &ctx,
-        &ast::Adt::Enum(parent_enum.clone()),
-        format!("is_{}", fn_name).as_str(),
-    )?;
+    let impl_def = find_struct_impl(&ctx, &parent_enum, &fn_name)?;
 
     let target = variant.syntax().text_range();
     acc.add(
-        AssistId("generate_enum_match_method", AssistKind::Generate),
+        AssistId("generate_enum_is_method", AssistKind::Generate),
         "Generate an `is_` method for an enum variant",
         target,
         |builder| {
-            let mut buf = String::with_capacity(512);
-
-            if impl_def.is_some() {
-                buf.push('\n');
-            }
-
             let vis = parent_enum.visibility().map_or(String::new(), |v| format!("{} ", v));
-            format_to!(
-                buf,
+            let method = format!(
                 "    /// Returns `true` if the {} is [`{}`].
-    {}fn is_{}(&self) -> bool {{
-        matches!(self, Self::{})
+    {}fn {}(&self) -> bool {{
+        matches!(self, Self::{}{})
     }}",
-                enum_lowercase_name,
-                variant_name,
-                vis,
-                fn_name,
-                variant_name
+                enum_lowercase_name, variant_name, vis, fn_name, variant_name, pattern_suffix,
             );
 
-            let start_offset = impl_def
-                .and_then(|impl_def| find_impl_block_end(impl_def, &mut buf))
-                .unwrap_or_else(|| {
-                    buf = generate_impl_text(&ast::Adt::Enum(parent_enum.clone()), &buf);
-                    parent_enum.syntax().text_range().end()
-                });
-
-            builder.insert(start_offset, buf);
+            add_method_to_adt(builder, &parent_enum, impl_def, &method);
         },
     )
 }
 
 #[cfg(test)]
 mod tests {
-    use test_utils::mark;
-
     use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
-    fn check_not_applicable(ra_fixture: &str) {
-        check_assist_not_applicable(generate_enum_match_method, ra_fixture)
-    }
-
     #[test]
-    fn test_generate_enum_match_from_variant() {
+    fn test_generate_enum_is_from_variant() {
         check_assist(
-            generate_enum_match_method,
+            generate_enum_is_method,
             r#"
 enum Variant {
     Undefined,
@@ -129,8 +101,9 @@ impl Variant {
     }
 
     #[test]
-    fn test_generate_enum_match_already_implemented() {
-        check_not_applicable(
+    fn test_generate_enum_is_already_implemented() {
+        check_assist_not_applicable(
+            generate_enum_is_method,
             r#"
 enum Variant {
     Undefined,
@@ -147,22 +120,59 @@ impl Variant {
     }
 
     #[test]
-    fn test_add_from_impl_no_element() {
-        mark::check!(test_gen_enum_match_on_non_unit_variant_not_implemented);
-        check_not_applicable(
+    fn test_generate_enum_is_from_tuple_variant() {
+        check_assist(
+            generate_enum_is_method,
             r#"
 enum Variant {
     Undefined,
     Minor(u32)$0,
     Major,
 }"#,
+            r#"enum Variant {
+    Undefined,
+    Minor(u32),
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor(..))
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_from_record_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor { foo: i32 }$0,
+    Major,
+}"#,
+            r#"enum Variant {
+    Undefined,
+    Minor { foo: i32 },
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor { .. })
+    }
+}"#,
         );
     }
 
     #[test]
-    fn test_generate_enum_match_from_variant_with_one_variant() {
+    fn test_generate_enum_is_from_variant_with_one_variant() {
         check_assist(
-            generate_enum_match_method,
+            generate_enum_is_method,
             r#"enum Variant { Undefi$0ned }"#,
             r#"
 enum Variant { Undefined }
@@ -177,9 +187,9 @@ impl Variant {
     }
 
     #[test]
-    fn test_generate_enum_match_from_variant_with_visibility_marker() {
+    fn test_generate_enum_is_from_variant_with_visibility_marker() {
         check_assist(
-            generate_enum_match_method,
+            generate_enum_is_method,
             r#"
 pub(crate) enum Variant {
     Undefined,
@@ -202,9 +212,9 @@ impl Variant {
     }
 
     #[test]
-    fn test_multiple_generate_enum_match_from_variant() {
+    fn test_multiple_generate_enum_is_from_variant() {
         check_assist(
-            generate_enum_match_method,
+            generate_enum_is_method,
             r#"
 enum Variant {
     Undefined,
diff --git a/crates/ide_assists/src/handlers/generate_enum_projection_method.rs b/crates/ide_assists/src/handlers/generate_enum_projection_method.rs
new file mode 100644
index 000000000..871bcab50
--- /dev/null
+++ b/crates/ide_assists/src/handlers/generate_enum_projection_method.rs
@@ -0,0 +1,331 @@
+use itertools::Itertools;
+use stdx::to_lower_snake_case;
+use syntax::ast::VisibilityOwner;
+use syntax::ast::{self, AstNode, NameOwner};
+
+use crate::{
+    utils::{add_method_to_adt, find_struct_impl},
+    AssistContext, AssistId, AssistKind, Assists,
+};
+
+// Assist: generate_enum_try_into_method
+//
+// Generate an `try_into_` method for an enum variant.
+//
+// ```
+// enum Value {
+//  Number(i32),
+//  Text(String)$0,
+// }
+// ```
+// ->
+// ```
+// enum Value {
+//  Number(i32),
+//  Text(String),
+// }
+//
+// impl Value {
+//     fn try_into_text(self) -> Result<String, Self> {
+//         if let Self::Text(v) = self {
+//             Ok(v)
+//         } else {
+//             Err(self)
+//         }
+//     }
+// }
+// ```
+pub(crate) fn generate_enum_try_into_method(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_enum_projection_method(
+        acc,
+        ctx,
+        "generate_enum_try_into_method",
+        "Generate an `try_into_` method for an enum variant",
+        ProjectionProps {
+            fn_name_prefix: "try_into",
+            self_param: "self",
+            return_prefix: "Result<",
+            return_suffix: ", Self>",
+            happy_case: "Ok",
+            sad_case: "Err(self)",
+        },
+    )
+}
+
+// Assist: generate_enum_as_method
+//
+// Generate an `as_` method for an enum variant.
+//
+// ```
+// enum Value {
+//  Number(i32),
+//  Text(String)$0,
+// }
+// ```
+// ->
+// ```
+// enum Value {
+//  Number(i32),
+//  Text(String),
+// }
+//
+// impl Value {
+//     fn as_text(&self) -> Option<&String> {
+//         if let Self::Text(v) = self {
+//             Some(v)
+//         } else {
+//             None
+//         }
+//     }
+// }
+// ```
+pub(crate) fn generate_enum_as_method(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_enum_projection_method(
+        acc,
+        ctx,
+        "generate_enum_as_method",
+        "Generate an `as_` method for an enum variant",
+        ProjectionProps {
+            fn_name_prefix: "as",
+            self_param: "&self",
+            return_prefix: "Option<&",
+            return_suffix: ">",
+            happy_case: "Some",
+            sad_case: "None",
+        },
+    )
+}
+
+struct ProjectionProps {
+    fn_name_prefix: &'static str,
+    self_param: &'static str,
+    return_prefix: &'static str,
+    return_suffix: &'static str,
+    happy_case: &'static str,
+    sad_case: &'static str,
+}
+
+fn generate_enum_projection_method(
+    acc: &mut Assists,
+    ctx: &AssistContext,
+    assist_id: &'static str,
+    assist_description: &str,
+    props: ProjectionProps,
+) -> Option<()> {
+    let variant = ctx.find_node_at_offset::<ast::Variant>()?;
+    let variant_name = variant.name()?;
+    let parent_enum = ast::Adt::Enum(variant.parent_enum());
+
+    let (pattern_suffix, field_type, bound_name) = match variant.kind() {
+        ast::StructKind::Record(record) => {
+            let (field,) = record.fields().collect_tuple()?;
+            let name = field.name()?.to_string();
+            let ty = field.ty()?;
+            let pattern_suffix = format!(" {{ {} }}", name);
+            (pattern_suffix, ty, name)
+        }
+        ast::StructKind::Tuple(tuple) => {
+            let (field,) = tuple.fields().collect_tuple()?;
+            let ty = field.ty()?;
+            ("(v)".to_owned(), ty, "v".to_owned())
+        }
+        ast::StructKind::Unit => return None,
+    };
+
+    let fn_name = format!("{}_{}", props.fn_name_prefix, &to_lower_snake_case(variant_name.text()));
+
+    // Return early if we've found an existing new fn
+    let impl_def = find_struct_impl(&ctx, &parent_enum, &fn_name)?;
+
+    let target = variant.syntax().text_range();
+    acc.add(AssistId(assist_id, AssistKind::Generate), assist_description, target, |builder| {
+        let vis = parent_enum.visibility().map_or(String::new(), |v| format!("{} ", v));
+        let method = format!(
+            "    {0}fn {1}({2}) -> {3}{4}{5} {{
+        if let Self::{6}{7} = self {{
+            {8}({9})
+        }} else {{
+            {10}
+        }}
+    }}",
+            vis,
+            fn_name,
+            props.self_param,
+            props.return_prefix,
+            field_type.syntax(),
+            props.return_suffix,
+            variant_name,
+            pattern_suffix,
+            props.happy_case,
+            bound_name,
+            props.sad_case,
+        );
+
+        add_method_to_adt(builder, &parent_enum, impl_def, &method);
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn test_generate_enum_try_into_tuple_variant() {
+        check_assist(
+            generate_enum_try_into_method,
+            r#"
+enum Value {
+    Number(i32),
+    Text(String)$0,
+}"#,
+            r#"enum Value {
+    Number(i32),
+    Text(String),
+}
+
+impl Value {
+    fn try_into_text(self) -> Result<String, Self> {
+        if let Self::Text(v) = self {
+            Ok(v)
+        } else {
+            Err(self)
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_try_into_already_implemented() {
+        check_assist_not_applicable(
+            generate_enum_try_into_method,
+            r#"enum Value {
+    Number(i32),
+    Text(String)$0,
+}
+
+impl Value {
+    fn try_into_text(self) -> Result<String, Self> {
+        if let Self::Text(v) = self {
+            Ok(v)
+        } else {
+            Err(self)
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_try_into_unit_variant() {
+        check_assist_not_applicable(
+            generate_enum_try_into_method,
+            r#"enum Value {
+    Number(i32),
+    Text(String),
+    Unit$0,
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_try_into_record_with_multiple_fields() {
+        check_assist_not_applicable(
+            generate_enum_try_into_method,
+            r#"enum Value {
+    Number(i32),
+    Text(String),
+    Both { first: i32, second: String }$0,
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_try_into_tuple_with_multiple_fields() {
+        check_assist_not_applicable(
+            generate_enum_try_into_method,
+            r#"enum Value {
+    Number(i32),
+    Text(String, String)$0,
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_try_into_record_variant() {
+        check_assist(
+            generate_enum_try_into_method,
+            r#"enum Value {
+    Number(i32),
+    Text { text: String }$0,
+}"#,
+            r#"enum Value {
+    Number(i32),
+    Text { text: String },
+}
+
+impl Value {
+    fn try_into_text(self) -> Result<String, Self> {
+        if let Self::Text { text } = self {
+            Ok(text)
+        } else {
+            Err(self)
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_as_tuple_variant() {
+        check_assist(
+            generate_enum_as_method,
+            r#"
+enum Value {
+    Number(i32),
+    Text(String)$0,
+}"#,
+            r#"enum Value {
+    Number(i32),
+    Text(String),
+}
+
+impl Value {
+    fn as_text(&self) -> Option<&String> {
+        if let Self::Text(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_as_record_variant() {
+        check_assist(
+            generate_enum_as_method,
+            r#"enum Value {
+    Number(i32),
+    Text { text: String }$0,
+}"#,
+            r#"enum Value {
+    Number(i32),
+    Text { text: String },
+}
+
+impl Value {
+    fn as_text(&self) -> Option<&String> {
+        if let Self::Text { text } = self {
+            Some(text)
+        } else {
+            None
+        }
+    }
+}"#,
+        );
+    }
+}
diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index 7067cf8b6..4c067d451 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -114,6 +114,7 @@ mod handlers {
     mod apply_demorgan;
     mod auto_import;
     mod change_visibility;
+    mod convert_for_to_iter_for_each;
     mod convert_integer_literal;
     mod early_return;
     mod expand_glob_import;
@@ -127,7 +128,8 @@ mod handlers {
     mod flip_trait_bound;
     mod generate_default_from_enum_variant;
     mod generate_derive;
-    mod generate_enum_match_method;
+    mod generate_enum_is_method;
+    mod generate_enum_projection_method;
     mod generate_from_impl_for_enum;
     mod generate_function;
     mod generate_getter;
@@ -175,6 +177,7 @@ mod handlers {
             apply_demorgan::apply_demorgan,
             auto_import::auto_import,
             change_visibility::change_visibility,
+            convert_for_to_iter_for_each::convert_for_to_iter_for_each,
             convert_integer_literal::convert_integer_literal,
             early_return::convert_to_guarded_return,
             expand_glob_import::expand_glob_import,
@@ -187,7 +190,9 @@ mod handlers {
             flip_trait_bound::flip_trait_bound,
             generate_default_from_enum_variant::generate_default_from_enum_variant,
             generate_derive::generate_derive,
-            generate_enum_match_method::generate_enum_match_method,
+            generate_enum_is_method::generate_enum_is_method,
+            generate_enum_projection_method::generate_enum_try_into_method,
+            generate_enum_projection_method::generate_enum_as_method,
             generate_from_impl_for_enum::generate_from_impl_for_enum,
             generate_function::generate_function,
             generate_getter::generate_getter,
diff --git a/crates/ide_assists/src/tests/generated.rs b/crates/ide_assists/src/tests/generated.rs
index 701091a6b..7f6dbbccf 100644
--- a/crates/ide_assists/src/tests/generated.rs
+++ b/crates/ide_assists/src/tests/generated.rs
@@ -193,6 +193,29 @@ pub(crate) fn frobnicate() {}
 }
 
 #[test]
+fn doctest_convert_for_to_iter_for_each() {
+    check_doc_test(
+        "convert_for_to_iter_for_each",
+        r#####"
+fn main() {
+    let x = vec![1, 2, 3];
+    for $0v in x {
+        let y = v * 2;
+    }
+}
+"#####,
+        r#####"
+fn main() {
+    let x = vec![1, 2, 3];
+    x.into_iter().for_each(|v| {
+        let y = v * 2;
+    });
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_convert_integer_literal() {
     check_doc_test(
         "convert_integer_literal",
@@ -460,9 +483,38 @@ struct Point {
 }
 
 #[test]
-fn doctest_generate_enum_match_method() {
+fn doctest_generate_enum_as_method() {
+    check_doc_test(
+        "generate_enum_as_method",
+        r#####"
+enum Value {
+ Number(i32),
+ Text(String)$0,
+}
+"#####,
+        r#####"
+enum Value {
+ Number(i32),
+ Text(String),
+}
+
+impl Value {
+    fn as_text(&self) -> Option<&String> {
+        if let Self::Text(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_generate_enum_is_method() {
     check_doc_test(
-        "generate_enum_match_method",
+        "generate_enum_is_method",
         r#####"
 enum Version {
  Undefined,
@@ -488,6 +540,35 @@ impl Version {
 }
 
 #[test]
+fn doctest_generate_enum_try_into_method() {
+    check_doc_test(
+        "generate_enum_try_into_method",
+        r#####"
+enum Value {
+ Number(i32),
+ Text(String)$0,
+}
+"#####,
+        r#####"
+enum Value {
+ Number(i32),
+ Text(String),
+}
+
+impl Value {
+    fn try_into_text(self) -> Result<String, Self> {
+        if let Self::Text(v) = self {
+            Ok(v)
+        } else {
+            Err(self)
+        }
+    }
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_generate_from_impl_for_enum() {
     check_doc_test(
         "generate_from_impl_for_enum",
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index 276792bc1..880ab6fe3 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -21,7 +21,7 @@ use syntax::{
 };
 
 use crate::{
-    assist_context::AssistContext,
+    assist_context::{AssistBuilder, AssistContext},
     ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
 };
 
@@ -464,3 +464,25 @@ fn generate_impl_text_inner(adt: &ast::Adt, trait_text: Option<&str>, code: &str
 
     buf
 }
+
+pub(crate) fn add_method_to_adt(
+    builder: &mut AssistBuilder,
+    adt: &ast::Adt,
+    impl_def: Option<ast::Impl>,
+    method: &str,
+) {
+    let mut buf = String::with_capacity(method.len() + 2);
+    if impl_def.is_some() {
+        buf.push('\n');
+    }
+    buf.push_str(method);
+
+    let start_offset = impl_def
+        .and_then(|impl_def| find_impl_block_end(impl_def, &mut buf))
+        .unwrap_or_else(|| {
+            buf = generate_impl_text(&adt, &buf);
+            adt.syntax().text_range().end()
+        });
+
+    builder.insert(start_offset, buf);
+}
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index e41171b57..d836c5d1a 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 itertools = "0.10.0"
 rowan = "0.12.2"
-rustc_lexer = { version = "707.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer = { version = "708.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 arrayvec = "0.5.1"
 once_cell = "1.3.1"