Hover doc link rewriting

7 files changed, 382 insertions, 17 deletions

diff --git a/Cargo.lock b/Cargo.lock
index ca3d14a09..bc36f0fab 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -95,6 +95,27 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
+name = "block-buffer"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c0940dc441f31689269e10ac70eb1002a3a1d3ad1390e030043662eb7fe4688b"
+dependencies = [
+ "block-padding",
+ "byte-tools",
+ "byteorder",
+ "generic-array",
+]
+
+[[package]]
+name = "block-padding"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa79dedbb091f449f1f39e53edf88d5dbe95f895dae6135a8d7b881fb5af73f5"
+dependencies = [
+ "byte-tools",
+]
+
+[[package]]
 name = "bstr"
 version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -104,6 +125,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "byte-tools"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
+
+[[package]]
 name = "byteorder"
 version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -196,15 +223,18 @@ dependencies = [
 ]
 
 [[package]]
-name = "clicolors-control"
-version = "1.0.1"
+name = "clap"
+version = "2.33.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "90082ee5dcdd64dc4e9e0d37fbf3ee325419e39c0092191e0393df65518f741e"
+checksum = "bdfa80d47f954d53a35a64987ca1422f495b8d6483c0fe9f7117b36c2a792129"
 dependencies = [
+ "ansi_term",
  "atty",
- "lazy_static",
- "libc",
- "winapi 0.3.9",
+ "bitflags",
+ "strsim",
+ "textwrap",
+ "unicode-width",
+ "vec_map",
 ]
 
 [[package]]
@@ -217,12 +247,28 @@ dependencies = [
 ]
 
 [[package]]
+name = "comrak"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e17058cc536cf290563e88787d7b9e6030ce4742943017cc2ffb71f88034021c"
+dependencies = [
+ "clap",
+ "entities",
+ "lazy_static",
+ "pest",
+ "pest_derive",
+ "regex",
+ "twoway",
+ "typed-arena",
+ "unicode_categories",
+]
+
+[[package]]
 name = "console"
-version = "0.10.3"
+version = "0.11.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2586208b33573b7f76ccfbe5adb076394c88deaf81b84d7213969805b0a952a7"
+checksum = "8c0994e656bba7b922d8dd1245db90672ffb701e684e45be58f20719d69abc5a"
 dependencies = [
- "clicolors-control",
  "encode_unicode",
  "lazy_static",
  "libc",
@@ -310,6 +356,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "524cbf6897b527295dff137cec09ecf3a05f4fddffd7dfcd1585403449e74198"
 
 [[package]]
+name = "digest"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3d0c8c8752312f9713efd397ff63acb9f85585afbf179282e720e7704954dd5"
+dependencies = [
+ "generic-array",
+]
+
+[[package]]
 name = "drop_bomb"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -343,6 +398,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a357d28ed41a50f9c765dbfe56cbc04a64e53e5fc58ba79fbc34c10ef3df831f"
 
 [[package]]
+name = "entities"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5320ae4c3782150d900b79807611a59a99fc9a1d61d686faafc24b93fc8d7ca"
+
+[[package]]
 name = "env_logger"
 version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -352,6 +413,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "fake-simd"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
+
+[[package]]
 name = "filetime"
 version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -435,6 +502,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3dcaa9ae7725d12cdb85b3ad99a434db70b468c09ded17e012d86b5c1010f7a7"
 
 [[package]]
+name = "generic-array"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c68f0274ae0e023facc3c97b2e00f076be70e254bc851d972503b328db79b2ec"
+dependencies = [
+ "typenum",
+]
+
+[[package]]
 name = "getrandom"
 version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -544,9 +620,9 @@ dependencies = [
 
 [[package]]
 name = "insta"
-version = "0.16.0"
+version = "0.16.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8386e795fb3927131ea4cede203c529a333652eb6dc4ff29616b832b27e9b096"
+checksum = "617e921abc813f96a3b00958c079e7bf1e2db998f8a04f1546dd967373a418ee"
 dependencies = [
  "console",
  "difference",
@@ -712,6 +788,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "maplit"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
+
+[[package]]
 name = "matchers"
 version = "0.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -882,6 +964,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b631f7e854af39a1739f401cf34a8a013dfe09eac4fa4dba91e9768bd28168d"
 
 [[package]]
+name = "opaque-debug"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2839e79665f131bdb5782e51f2c6c9599c133c6098982a54c794358bf432529c"
+
+[[package]]
 name = "parking_lot"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -937,6 +1025,49 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d4fd5641d01c8f18a23da7b6fe29298ff4b55afcccdf78973b24cf3175fee32e"
 
 [[package]]
+name = "pest"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10f4872ae94d7b90ae48754df22fd42ad52ce740b8f370b03da4835417403e53"
+dependencies = [
+ "ucd-trie",
+]
+
+[[package]]
+name = "pest_derive"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "833d1ae558dc601e9a60366421196a8d94bc0ac980476d0b67e1d0988d72b2d0"
+dependencies = [
+ "pest",
+ "pest_generator",
+]
+
+[[package]]
+name = "pest_generator"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "99b8db626e31e5b81787b9783425769681b347011cc59471e33ea46d2ea0cf55"
+dependencies = [
+ "pest",
+ "pest_meta",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "pest_meta"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54be6e404f5317079812fc8f9f5279de376d8856929e21c184ecf6bbd692a11d"
+dependencies = [
+ "maplit",
+ "pest",
+ "sha-1",
+]
+
+[[package]]
 name = "petgraph"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1133,6 +1264,7 @@ dependencies = [
 name = "ra_ide"
 version = "0.1.0"
 dependencies = [
+ "comrak",
  "either",
  "indexmap",
  "insta",
@@ -1143,8 +1275,10 @@ dependencies = [
  "ra_db",
  "ra_fmt",
  "ra_hir",
+ "ra_hir_def",
  "ra_ide_db",
  "ra_prof",
+ "ra_project_model",
  "ra_ssr",
  "ra_syntax",
  "ra_text_edit",
@@ -1152,6 +1286,7 @@ dependencies = [
  "rustc-hash",
  "stdx",
  "test_utils",
+ "url",
 ]
 
 [[package]]
@@ -1654,6 +1789,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "sha-1"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7d94d0bede923b3cea61f3f1ff57ff8cdfd77b400fb8f9998949e0cf04163df"
+dependencies = [
+ "block-buffer",
+ "digest",
+ "fake-simd",
+ "opaque-debug",
+]
+
+[[package]]
 name = "sharded-slab"
 version = "0.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1688,6 +1835,12 @@ name = "stdx"
 version = "0.1.0"
 
 [[package]]
+name = "strsim"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
+
+[[package]]
 name = "superslice"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1767,6 +1920,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f03e7efdedc3bc78cb2337f1e2785c39e45f5ef762d9e4ebb137fff7380a6d8a"
 
 [[package]]
+name = "textwrap"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
+dependencies = [
+ "unicode-width",
+]
+
+[[package]]
 name = "thin-dst"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1879,6 +2041,40 @@ dependencies = [
 ]
 
 [[package]]
+name = "twoway"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b40075910de3a912adbd80b5d8bad6ad10a23eeb1f5bf9d4006839e899ba5bc"
+dependencies = [
+ "memchr",
+ "unchecked-index",
+]
+
+[[package]]
+name = "typed-arena"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a9b2228007eba4120145f785df0f6c92ea538f5a3635a612ecf4e334c8c1446d"
+
+[[package]]
+name = "typenum"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "373c8a200f9e67a0c95e62a4f52fbf80c23b4381c05a17845531982fa99e6b33"
+
+[[package]]
+name = "ucd-trie"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
+
+[[package]]
+name = "unchecked-index"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eeba86d422ce181a719445e51872fa30f1f7413b62becb52e95ec91aa262d85c"
+
+[[package]]
 name = "unicode-bidi"
 version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1903,12 +2099,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e83e153d1053cbb5a118eeff7fd5be06ed99153f00dbcd8ae310c5fb2b22edc0"
 
 [[package]]
+name = "unicode-width"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
+
+[[package]]
 name = "unicode-xid"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
 
 [[package]]
+name = "unicode_categories"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39ec24b3121d976906ece63c9daad25b85969647682eee313cb5779fdd69e14e"
+
+[[package]]
 name = "url"
 version = "2.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1921,6 +2129,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "vec_map"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
+
+[[package]]
 name = "vfs"
 version = "0.1.0"
 dependencies = [
diff --git a/crates/ra_ide/Cargo.toml b/crates/ra_ide/Cargo.toml
index bbc6a5c9b..e5fdf5aa1 100644
--- a/crates/ra_ide/Cargo.toml
+++ b/crates/ra_ide/Cargo.toml
@@ -17,6 +17,8 @@ itertools = "0.9.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
 rand = { version = "0.7.3", features = ["small_rng"] }
+comrak = "0.7.0"
+url = "*"
 
 stdx = { path = "../stdx" }
 
@@ -30,6 +32,8 @@ ra_prof = { path = "../ra_prof" }
 test_utils = { path = "../test_utils" }
 ra_assists = { path = "../ra_assists" }
 ra_ssr = { path = "../ra_ssr" }
+ra_project_model = { path = "../ra_project_model" }
+ra_hir_def = { path = "../ra_hir_def" }
 
 # ra_ide should depend only on the top-level `hir` package. if you need
 # something from some `hir_xxx` subpackage, reexport the API via `hir`.
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index c3e36a387..079195184 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -1,8 +1,8 @@
 use std::iter::once;
 
 use hir::{
-    Adt, AsAssocItem, AssocItemContainer, Documentation, FieldSource, HasSource, HirDisplay,
-    Module, ModuleDef, ModuleSource, Semantics,
+    Adt, AsAssocItem, AssocItemContainer, FieldSource, HasSource, HirDisplay, ModuleDef,
+    ModuleSource, Semantics, Module, Documentation
 };
 use itertools::Itertools;
 use ra_db::SourceDatabase;
@@ -11,6 +11,8 @@ use ra_ide_db::{
     RootDatabase,
 };
 use ra_syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset};
+use ra_project_model::ProjectWorkspace;
+use ra_hir_def::{item_scope::ItemInNs, db::DefDatabase, ModuleDefId};
 
 use crate::{
     display::{
@@ -65,6 +67,13 @@ pub struct HoverGotoTypeData {
     pub nav: NavigationTarget,
 }
 
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use comrak::{parse_document,format_commonmark, ComrakOptions, Arena};
+use comrak::nodes::NodeValue;
+use url::Url;
+use ra_ide_db::imports_locator::ImportsLocator;
+
 /// Contains the results when hovering over an item
 #[derive(Debug, Default)]
 pub struct HoverResult {
@@ -118,7 +127,7 @@ impl HoverResult {
 //
 // Shows additional information, like type of an expression or documentation for definition when "focusing" code.
 // Focusing is usually hovering with a mouse, but can also be triggered with a shortcut.
-pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<HoverResult>> {
+pub(crate) fn hover(db: &RootDatabase, position: FilePosition, workspaces: Arc<Vec<ProjectWorkspace>>) -> Option<RangeInfo<HoverResult>> {
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id).syntax().clone();
     let token = pick_best(file.token_at_offset(position.offset))?;
@@ -138,7 +147,8 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         }
     } {
         let range = sema.original_range(&node).range;
-        res.extend(hover_text_from_name_kind(db, name_kind));
+        let text = hover_text_from_name_kind(db, name_kind.clone()).map(|text| rewrite_links(db, &text, &name_kind, workspaces).unwrap_or(text));
+        res.extend(text);
 
         if !res.is_empty() {
             if let Some(action) = show_implementations_action(db, name_kind) {
@@ -379,6 +389,90 @@ fn hover_text_from_name_kind(db: &RootDatabase, def: Definition) -> Option<Strin
     }
 }
 
+/// Rewrite documentation links in markdown to point to local documentation/docs.rs
+fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition, workspaces: Arc<Vec<ProjectWorkspace>>) -> Option<String> {
+    // FIXME: Fail early
+    if let (Some(name), Some(module)) = (definition.name(db), definition.module(db)) {
+        let krate_name = module.krate().display_name(db)?;
+        let arena = Arena::new();
+        let doc = parse_document(&arena, markdown, &ComrakOptions::default());
+        let path = module.path_to_root(db);
+        let mut doc_target_dirs = workspaces
+            .iter()
+            .filter_map(|workspace| if let ProjectWorkspace::Cargo{cargo: cargo_workspace, ..} = workspace {Some(cargo_workspace)} else {None})
+            .map(|workspace| workspace.workspace_root())
+            // TODO: `target` is configurable in cargo config, we should respect it
+            .map(|root| root.join("target/doc"));
+
+        iter_nodes(doc, &|node| {
+            match &mut node.data.borrow_mut().value {
+                &mut NodeValue::Link(ref mut link) => {
+                    match Url::parse(&String::from_utf8(link.url.clone()).unwrap()) {
+                        // If this is a valid absolute URL don't touch it
+                        Ok(_) => (),
+                        // If contains .html            file-based link to new page
+                        // If starts with #fragment     file-based link to fragment on current page
+                        // If contains ::               module-based link
+                        Err(_) => {
+                            let link_str = String::from_utf8(link.url.clone()).unwrap();
+                            let resolved = try_resolve_path(db, &mut doc_target_dirs.clone(), definition, &link_str)
+                                .or_else(|| try_resolve_intra(db, &mut doc_target_dirs.clone(), definition, &link_str));
+
+                            if let Some(resolved) = resolved {
+                                link.url = resolved.as_bytes().to_vec();
+                            }
+
+                        }
+                    }
+                },
+                _ => ()
+            }
+        });
+        let mut out = Vec::new();
+        format_commonmark(doc, &ComrakOptions::default(), &mut out);
+        Some(String::from_utf8(out).unwrap())
+    } else {
+        // eprintln!("WARN: Unable to determine name or module for hover; link rewriting disabled.");
+        None
+    }
+}
+
+/// Try to resolve path to local documentation via intra-doc-links (i.e. `super::gateway::Shard`)
+fn try_resolve_intra(db: &RootDatabase, doc_target_dirs: impl Iterator<Item = PathBuf>, definition: &Definition, link: &str) -> Option<String> {
+    None
+}
+
+/// Try to resolve path to local documentation via path-based links (i.e. `../gateway/struct.Shard.html`)
+fn try_resolve_path(db: &RootDatabase, doc_target_dirs: impl Iterator<Item = PathBuf>, definition: &Definition, link: &str) -> Option<String> {
+    let ns = if let Definition::ModuleDef(moddef) = definition {
+        ItemInNs::Types(moddef.clone().into())
+    } else {
+        return None;
+    };
+    let krate = definition.module(db)?.krate();
+    let import_map = db.import_map(krate.into());
+    let base = import_map.path_of(ns).unwrap();
+    let base = base.segments.iter().map(|name| format!("{}", name)).collect::<PathBuf>();
+
+    doc_target_dirs
+        .map(|dir| dir.join(format!("{}", krate.display_name(db).unwrap())).join(base.join("..").join(link)))
+        .inspect(|path| eprintln!("candidate {}", path.display()))
+        .filter(|path| path.exists())
+        // slice out the UNC '\?\' added by canonicalize
+        .map(|path| format!("file:///{}", path.display()))
+        // \. is treated as an escape in vscode's markdown hover rendering
+        .map(|path_str| path_str.replace("\\", "/"))
+        .next()
+}
+
+fn iter_nodes<'a, F>(node: &'a comrak::nodes::AstNode<'a>, f: &F)
+    where F : Fn(&'a comrak::nodes::AstNode<'a>) {
+    f(node);
+    for c in node.children() {
+        iter_nodes(c, f);
+    }
+}
+
 fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
     return tokens.max_by_key(priority);
     fn priority(n: &SyntaxToken) -> usize {
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index ecac5134e..d56d52d30 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -54,6 +54,7 @@ use ra_ide_db::{
     LineIndexDatabase,
 };
 use ra_syntax::{SourceFile, TextRange, TextSize};
+use ra_project_model::ProjectWorkspace;
 
 use crate::display::ToNav;
 
@@ -389,8 +390,8 @@ impl Analysis {
     }
 
     /// Returns a short text describing element at position.
-    pub fn hover(&self, position: FilePosition) -> Cancelable<Option<RangeInfo<HoverResult>>> {
-        self.with_db(|db| hover::hover(db, position))
+    pub fn hover(&self, position: FilePosition, workspaces: Arc<Vec<ProjectWorkspace>>) -> Cancelable<Option<RangeInfo<HoverResult>>> {
+        self.with_db(|db| hover::hover(db, position, workspaces))
     }
 
     /// Computes parameter information for the given call expression.
diff --git a/crates/ra_syntax/src/ast/test.txt b/crates/ra_syntax/src/ast/test.txt
new file mode 100644
index 000000000..f746bf1e7
--- /dev/null
+++ b/crates/ra_syntax/src/ast/test.txt
@@ -0,0 +1,15 @@
+The context is a general utility struct provided on event dispatches, which
+helps with dealing with the current "context" of the event dispatch.
+The context also acts as a general high-level interface over the associated
+[`Shard`] which received the event, or the low-level [`http`] module.
+
+The context contains "shortcuts", like for interacting with the shard.
+Methods like [`set_activity`] will unlock the shard and perform an update for
+you to save a bit of work.
+
+A context will only live for the event it was dispatched for. After the
+event handler finished, it is destroyed and will not be re-used.
+
+[`Shard`]: ../gateway/struct.Shard.html
+[`http`]: ../http/index.html
+[`set_activity`]: #method.set_activity
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index a8f2454fd..323d78bbc 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -146,3 +146,39 @@ impl Iterator for CommentIter {
         self.iter.by_ref().find_map(|el| el.into_token().and_then(ast::Comment::cast))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use comrak::{parse_document,format_commonmark, ComrakOptions, Arena};
+    use comrak::nodes::{AstNode, NodeValue};
+
+    fn iter_nodes<'a, F>(node: &'a AstNode<'a>, f: &F)
+        where F : Fn(&'a AstNode<'a>) {
+        f(node);
+        for c in node.children() {
+            iter_nodes(c, f);
+        }
+    }
+
+    #[allow(non_snake_case)]
+    #[test]
+    fn test_link_rewrite() {
+        let src = include_str!("./test.txt");
+
+        let arena = Arena::new();
+        let doc = parse_document(&arena, src, &ComrakOptions::default());
+
+        iter_nodes(doc, &|node| {
+            match &mut node.data.borrow_mut().value {
+                &mut NodeValue::Link(ref mut link) => {
+                    link.url = "https://www.google.com".as_bytes().to_vec();
+                },
+                _ => ()
+            }
+        });
+
+        let mut out = Vec::new();
+        format_commonmark(doc, &ComrakOptions::default(), &mut out);
+        panic!("{}", String::from_utf8(out).unwrap());
+    }
+}
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index e35a5e846..19da25f96 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -5,6 +5,7 @@
 use std::{
     io::Write as _,
     process::{self, Stdio},
+    sync::Arc
 };
 
 use lsp_server::ErrorCode;