1 files changed, 86 insertions, 0 deletions
diff --git a/third_party/rust/bindgen/ir/dot.rs b/third_party/rust/bindgen/ir/dot.rs
new file mode 100644
index 0000000000..f7d07f19e2
--- /dev/null
+++ b/third_party/rust/bindgen/ir/dot.rs
@@ -0,0 +1,86 @@
+//! Generating Graphviz `dot` files from our IR.
+
+use super::context::{BindgenContext, ItemId};
+use super::traversal::Trace;
+use std::fs::File;
+use std::io::{self, Write};
+use std::path::Path;
+
+/// A trait for anything that can write attributes as `<table>` rows to a dot
+/// file.
+pub trait DotAttributes {
+    /// Write this thing's attributes to the given output. Each attribute must
+    /// be its own `<tr>...</tr>`.
+    fn dot_attributes<W>(
+        &self,
+        ctx: &BindgenContext,
+        out: &mut W,
+    ) -> io::Result<()>
+    where
+        W: io::Write;
+}
+
+/// Write a graphviz dot file containing our IR.
+pub fn write_dot_file<P>(ctx: &BindgenContext, path: P) -> io::Result<()>
+where
+    P: AsRef<Path>,
+{
+    let file = File::create(path)?;
+    let mut dot_file = io::BufWriter::new(file);
+    writeln!(&mut dot_file, "digraph {{")?;
+
+    let mut err: Option<io::Result<_>> = None;
+
+    for (id, item) in ctx.items() {
+        let is_allowlisted = ctx.allowlisted_items().contains(&id);
+
+        writeln!(
+            &mut dot_file,
+            r#"{} [fontname="courier", color={}, label=< <table border="0" align="left">"#,
+            id.as_usize(),
+            if is_allowlisted { "black" } else { "gray" }
+        )?;
+        item.dot_attributes(ctx, &mut dot_file)?;
+        writeln!(&mut dot_file, r#"</table> >];"#)?;
+
+        item.trace(
+            ctx,
+            &mut |sub_id: ItemId, edge_kind| {
+                if err.is_some() {
+                    return;
+                }
+
+                match writeln!(
+                    &mut dot_file,
+                    "{} -> {} [label={:?}, color={}];",
+                    id.as_usize(),
+                    sub_id.as_usize(),
+                    edge_kind,
+                    if is_allowlisted { "black" } else { "gray" }
+                ) {
+                    Ok(_) => {}
+                    Err(e) => err = Some(Err(e)),
+                }
+            },
+            &(),
+        );
+
+        if let Some(err) = err {
+            return err;
+        }
+
+        if let Some(module) = item.as_module() {
+            for child in module.children() {
+                writeln!(
+                    &mut dot_file,
+                    "{} -> {} [style=dotted, color=gray]",
+                    item.id().as_usize(),
+                    child.as_usize()
+                )?;
+            }
+        }
+    }
+
+    writeln!(&mut dot_file, "}}")?;
+    Ok(())
+}