5 files changed, 119 insertions, 18 deletions

diff --git a/crates/ra_assists/src/assists/add_derive.rs b/crates/ra_assists/src/assists/add_derive.rs
index 77ecc33c9..d3ba634c4 100644
--- a/crates/ra_assists/src/assists/add_derive.rs
+++ b/crates/ra_assists/src/assists/add_derive.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
-
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast::{self, AstNode, AttrsOwner},
@@ -9,6 +7,22 @@ use ra_syntax::{
 
 use crate::{Assist, AssistCtx, AssistId};
 
+// Assist: add_derive
+// Adds a new `#[derive()]` clause to a struct or enum.
+// ```
+// struct Point {
+//     x: u32,
+//     y: u32,<|>
+// }
+// ```
+// ->
+// ```
+// #[derive()]
+// struct Point {
+//     x: u32,
+//     y: u32,
+// }
+// ```
 pub(crate) fn add_derive(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
     let node_start = derive_insertion_offset(&nominal)?;
diff --git a/crates/ra_assists/src/assists/add_explicit_type.rs b/crates/ra_assists/src/assists/add_explicit_type.rs
index 8c83dc987..33b7bea7f 100644
--- a/crates/ra_assists/src/assists/add_explicit_type.rs
+++ b/crates/ra_assists/src/assists/add_explicit_type.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
-
 use hir::{db::HirDatabase, HirDisplay, Ty};
 use ra_syntax::{
     ast::{self, AstNode, LetStmt, NameOwner},
@@ -8,7 +6,19 @@ use ra_syntax::{
 
 use crate::{Assist, AssistCtx, AssistId};
 
-/// Add explicit type assist.
+// Assist: add_explicit_type
+// Specify type for a let binding
+// ```
+// fn main() {
+//     let x<|> = 92;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let x: i32 = 92;
+// }
+// ```
 pub(crate) fn add_explicit_type(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let stmt = ctx.node_at_offset::<LetStmt>()?;
     let expr = stmt.initializer()?;
diff --git a/crates/ra_assists/src/assists/add_impl.rs b/crates/ra_assists/src/assists/add_impl.rs
index 94801fbc9..40bc5c464 100644
--- a/crates/ra_assists/src/assists/add_impl.rs
+++ b/crates/ra_assists/src/assists/add_impl.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
-
 use format_buf::format;
 use hir::db::HirDatabase;
 use join_to_string::join;
@@ -10,6 +8,23 @@ use ra_syntax::{
 
 use crate::{Assist, AssistCtx, AssistId};
 
+// Assist: add_impl
+// Adds a new inherent impl for a type
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,<|>
+// }
+// ```
+// ->
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,
+// }
+//
+// impl<T: Clone> Ctx<T> {
+//
+// }
+// ```
 pub(crate) fn add_impl(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
     let name = nominal.name()?;
diff --git a/crates/ra_assists/src/assists/add_missing_impl_members.rs b/crates/ra_assists/src/assists/add_missing_impl_members.rs
index 565b96fb5..36fa6f9ea 100644
--- a/crates/ra_assists/src/assists/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/assists/add_missing_impl_members.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
-
 use hir::{db::HirDatabase, HasSource};
 use ra_syntax::{
     ast::{self, edit, make, AstNode, NameOwner},
@@ -14,6 +12,32 @@ enum AddMissingImplMembersMode {
     NoDefaultMethods,
 }
 
+// Assist: add_impl_missing_members
+// Adds scaffold for required impl members
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {<|>
+//
+// }
+// ```
+// ->
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     fn foo(&self) { unimplemented!() }
+//
+// }
+// ```
 pub(crate) fn add_missing_impl_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     add_missing_impl_members_inner(
         ctx,
@@ -23,6 +47,36 @@ pub(crate) fn add_missing_impl_members(ctx: AssistCtx<impl HirDatabase>) -> Opti
     )
 }
 
+// Assist: add_impl_default_members
+// Adds scaffold for overriding default impl members
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     Type X = ();
+//     fn foo(&self) {}<|>
+//
+// }
+// ```
+// ->
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     Type X = ();
+//     fn foo(&self) {}
+//     fn bar(&self) {}
+//
+// }
+// ```
 pub(crate) fn add_missing_default_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     add_missing_impl_members_inner(
         ctx,
diff --git a/crates/ra_assists/src/assists/apply_demorgan.rs b/crates/ra_assists/src/assists/apply_demorgan.rs
index 5f2b0dd18..a072f63e7 100644
--- a/crates/ra_assists/src/assists/apply_demorgan.rs
+++ b/crates/ra_assists/src/assists/apply_demorgan.rs
@@ -1,18 +1,26 @@
-//! This contains the functions associated with the demorgan assist.
-//! This assist transforms boolean expressions of the form `!a || !b` into
-//! `!(a && b)`.
 use hir::db::HirDatabase;
 use ra_syntax::ast::{self, AstNode};
 use ra_syntax::SyntaxNode;
 
 use crate::{Assist, AssistCtx, AssistId};
 
-/// Assist for applying demorgan's law
-///
-/// This transforms expressions of the form `!l || !r` into `!(l && r)`.
-/// This also works with `&&`. This assist can only be applied with the cursor
-/// on either `||` or `&&`, with both operands being a negation of some kind.
-/// This means something of the form `!x` or `x != y`.
+// Assist: apply_demorgan
+// Apply [De Morgan's law](https://en.wikipedia.org/wiki/De_Morgan%27s_laws).
+// This transforms expressions of the form `!l || !r` into `!(l && r)`.
+// This also works with `&&`. This assist can only be applied with the cursor
+// on either `||` or `&&`, with both operands being a negation of some kind.
+// This means something of the form `!x` or `x != y`.
+// ```
+// fn main() {
+//     if x != 4 ||<|> !y {}
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     if !(x == 4 && y) {}
+// }
+// ```
 pub(crate) fn apply_demorgan(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let expr = ctx.node_at_offset::<ast::BinExpr>()?;
     let op = expr.op_kind()?;