12 files changed, 166 insertions, 1 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 0e1234b72..f9c34547e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -320,6 +320,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc4b29f4b9bb94bf267d57269fd0706d343a160937108e9619fe380645428abb"
 
 [[package]]
+name = "dot"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a74b6c4d4a1cff5f454164363c16b72fa12463ca6b31f4b5f2035a65fa3d5906"
+
+[[package]]
 name = "drop_bomb"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -588,6 +594,7 @@ version = "0.0.0"
 dependencies = [
  "cfg",
  "cov-mark",
+ "dot",
  "either",
  "expect-test",
  "hir",
diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
index f04bcf531..88f3d09d3 100644
--- a/crates/ide/Cargo.toml
+++ b/crates/ide/Cargo.toml
@@ -20,6 +20,7 @@ oorandom = "11.1.2"
 pulldown-cmark-to-cmark = "6.0.0"
 pulldown-cmark = { version = "0.8.0", default-features = false }
 url = "2.1.1"
+dot = "0.1.4"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 8e5b72044..34360501a 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -49,6 +49,7 @@ mod syntax_tree;
 mod typing;
 mod markdown_remove;
 mod doc_links;
+mod view_crate_graph;
 
 use std::sync::Arc;
 
@@ -287,6 +288,10 @@ impl Analysis {
         self.with_db(|db| view_hir::view_hir(&db, position))
     }
 
+    pub fn view_crate_graph(&self) -> Cancelable<Result<String, String>> {
+        self.with_db(|db| view_crate_graph::view_crate_graph(&db))
+    }
+
     pub fn expand_macro(&self, position: FilePosition) -> Cancelable<Option<ExpandedMacro>> {
         self.with_db(|db| expand_macro::expand_macro(db, position))
     }
diff --git a/crates/ide/src/view_crate_graph.rs b/crates/ide/src/view_crate_graph.rs
new file mode 100644
index 000000000..5e4ba881e
--- /dev/null
+++ b/crates/ide/src/view_crate_graph.rs
@@ -0,0 +1,111 @@
+use std::{
+    error::Error,
+    io::{Read, Write},
+    process::{Command, Stdio},
+    sync::Arc,
+};
+
+use dot::{Id, LabelText};
+use ide_db::{
+    base_db::{CrateGraph, CrateId, Dependency, SourceDatabase, SourceDatabaseExt},
+    RootDatabase,
+};
+use rustc_hash::FxHashSet;
+
+// Feature: View Crate Graph
+//
+// Renders the currently loaded crate graph as an SVG graphic. Requires the `dot` tool, which
+// is part of graphviz, to be installed.
+//
+// Only workspace crates are included, no crates.io dependencies or sysroot crates.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: View Crate Graph**
+// |===
+pub(crate) fn view_crate_graph(db: &RootDatabase) -> Result<String, String> {
+    let crate_graph = db.crate_graph();
+    let crates_to_render = crate_graph
+        .iter()
+        .filter(|krate| {
+            // Only render workspace crates
+            let root_id = db.file_source_root(crate_graph[*krate].root_file_id);
+            !db.source_root(root_id).is_library
+        })
+        .collect();
+    let graph = DotCrateGraph { graph: crate_graph, crates_to_render };
+
+    let mut dot = Vec::new();
+    dot::render(&graph, &mut dot).unwrap();
+
+    render_svg(&dot).map_err(|e| e.to_string())
+}
+
+fn render_svg(dot: &[u8]) -> Result<String, Box<dyn Error>> {
+    // We shell out to `dot` to render to SVG, as there does not seem to be a pure-Rust renderer.
+    let child = Command::new("dot")
+        .arg("-Tsvg")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .spawn()
+        .map_err(|err| format!("failed to spawn `dot`: {}", err))?;
+    child.stdin.unwrap().write_all(&dot)?;
+
+    let mut svg = String::new();
+    child.stdout.unwrap().read_to_string(&mut svg)?;
+    Ok(svg)
+}
+
+struct DotCrateGraph {
+    graph: Arc<CrateGraph>,
+    crates_to_render: FxHashSet<CrateId>,
+}
+
+type Edge<'a> = (CrateId, &'a Dependency);
+
+impl<'a> dot::GraphWalk<'a, CrateId, Edge<'a>> for DotCrateGraph {
+    fn nodes(&'a self) -> dot::Nodes<'a, CrateId> {
+        self.crates_to_render.iter().copied().collect()
+    }
+
+    fn edges(&'a self) -> dot::Edges<'a, Edge<'a>> {
+        self.crates_to_render
+            .iter()
+            .flat_map(|krate| {
+                self.graph[*krate]
+                    .dependencies
+                    .iter()
+                    .filter(|dep| self.crates_to_render.contains(&dep.crate_id))
+                    .map(move |dep| (*krate, dep))
+            })
+            .collect()
+    }
+
+    fn source(&'a self, edge: &Edge<'a>) -> CrateId {
+        edge.0
+    }
+
+    fn target(&'a self, edge: &Edge<'a>) -> CrateId {
+        edge.1.crate_id
+    }
+}
+
+impl<'a> dot::Labeller<'a, CrateId, Edge<'a>> for DotCrateGraph {
+    fn graph_id(&'a self) -> Id<'a> {
+        Id::new("rust_analyzer_crate_graph").unwrap()
+    }
+
+    fn node_id(&'a self, n: &CrateId) -> Id<'a> {
+        Id::new(format!("_{}", n.0)).unwrap()
+    }
+
+    fn node_shape(&'a self, _node: &CrateId) -> Option<LabelText<'a>> {
+        Some(LabelText::LabelStr("box".into()))
+    }
+
+    fn node_label(&'a self, n: &CrateId) -> LabelText<'a> {
+        let name = self.graph[*n].display_name.as_ref().map_or("(unnamed crate)", |name| &*name);
+        LabelText::LabelStr(name.into())
+    }
+}
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index f6e40f872..dafbab6d0 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -117,6 +117,12 @@ pub(crate) fn handle_view_hir(
     Ok(res)
 }
 
+pub(crate) fn handle_view_crate_graph(snap: GlobalStateSnapshot, (): ()) -> Result<String> {
+    let _p = profile::span("handle_view_crate_graph");
+    let res = snap.analysis.view_crate_graph()??;
+    Ok(res)
+}
+
 pub(crate) fn handle_expand_macro(
     snap: GlobalStateSnapshot,
     params: lsp_ext::ExpandMacroParams,
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index b8835a534..3bd098058 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -61,6 +61,14 @@ impl Request for ViewHir {
     const METHOD: &'static str = "rust-analyzer/viewHir";
 }
 
+pub enum ViewCrateGraph {}
+
+impl Request for ViewCrateGraph {
+    type Params = ();
+    type Result = String;
+    const METHOD: &'static str = "rust-analyzer/viewCrateGraph";
+}
+
 pub enum ExpandMacro {}
 
 impl Request for ExpandMacro {
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index ce7ece559..c7bd7eee1 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -513,6 +513,7 @@ impl GlobalState {
             .on::<lsp_ext::AnalyzerStatus>(handlers::handle_analyzer_status)
             .on::<lsp_ext::SyntaxTree>(handlers::handle_syntax_tree)
             .on::<lsp_ext::ViewHir>(handlers::handle_view_hir)
+            .on::<lsp_ext::ViewCrateGraph>(handlers::handle_view_crate_graph)
             .on::<lsp_ext::ExpandMacro>(handlers::handle_expand_macro)
             .on::<lsp_ext::ParentModule>(handlers::handle_parent_module)
             .on::<lsp_ext::Runnables>(handlers::handle_runnables)
diff --git a/docs/dev/lsp-extensions.md b/docs/dev/lsp-extensions.md
index f0f981802..8fcd72d5d 100644
--- a/docs/dev/lsp-extensions.md
+++ b/docs/dev/lsp-extensions.md
@@ -1,5 +1,5 @@
 <!---
-lsp_ext.rs hash: 28a9d5a24b7ca396
+lsp_ext.rs hash: 6e57fc1b345b00e9
 
 If you need to change the above hash to make the test pass, please check if you
 need to adjust this doc as well and ping this issue:
@@ -486,6 +486,16 @@ Primarily for debugging, but very useful for all people working on rust-analyzer
 Returns a textual representation of the HIR of the function containing the cursor.
 For debugging or when working on rust-analyzer itself.
 
+## View Crate Graph
+
+**Method:** `rust-analyzer/viewCrateGraph`
+
+**Request:** `null`
+
+**Response:** `string`
+
+Renders rust-analyzer's crate graph as an SVG image.
+
 ## Expand Macro
 
 **Method:** `rust-analyzer/expandMacro`
diff --git a/editors/code/package.json b/editors/code/package.json
index f35d30898..0f38a1673 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -110,6 +110,11 @@
                 "category": "Rust Analyzer"
             },
             {
+                "command": "rust-analyzer.viewCrateGraph",
+                "title": "View Crate Graph",
+                "category": "Rust Analyzer"
+            },
+            {
                 "command": "rust-analyzer.expandMacro",
                 "title": "Expand macro recursively",
                 "category": "Rust Analyzer"
diff --git a/editors/code/src/commands.ts b/editors/code/src/commands.ts
index 4092435db..8ab259af2 100644
--- a/editors/code/src/commands.ts
+++ b/editors/code/src/commands.ts
@@ -429,6 +429,14 @@ export function viewHir(ctx: Ctx): Cmd {
     };
 }
 
+export function viewCrateGraph(ctx: Ctx): Cmd {
+    return async () => {
+        const panel = vscode.window.createWebviewPanel("rust-analyzer.crate-graph", "rust-analyzer crate graph", vscode.ViewColumn.Two);
+        const svg = await ctx.client.sendRequest(ra.viewCrateGraph);
+        panel.webview.html = svg;
+    };
+}
+
 // Opens the virtual file that will show the syntax tree
 //
 // The contents of the file come from the `TextDocumentContentProvider`
diff --git a/editors/code/src/lsp_ext.ts b/editors/code/src/lsp_ext.ts
index f78de894b..aa745a65c 100644
--- a/editors/code/src/lsp_ext.ts
+++ b/editors/code/src/lsp_ext.ts
@@ -27,6 +27,8 @@ export const syntaxTree = new lc.RequestType<SyntaxTreeParams, string, void>("ru
 
 export const viewHir = new lc.RequestType<lc.TextDocumentPositionParams, string, void>("rust-analyzer/viewHir");
 
+export const viewCrateGraph = new lc.RequestType0<string, void>("rust-analyzer/viewCrateGraph");
+
 export interface ExpandMacroParams {
     textDocument: lc.TextDocumentIdentifier;
     position: lc.Position;
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 643fb643f..516322d03 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -106,6 +106,7 @@ async function tryActivate(context: vscode.ExtensionContext) {
     ctx.registerCommand('parentModule', commands.parentModule);
     ctx.registerCommand('syntaxTree', commands.syntaxTree);
     ctx.registerCommand('viewHir', commands.viewHir);
+    ctx.registerCommand('viewCrateGraph', commands.viewCrateGraph);
     ctx.registerCommand('expandMacro', commands.expandMacro);
     ctx.registerCommand('run', commands.run);
     ctx.registerCommand('copyRunCommandLine', commands.copyRunCommandLine);