Make graphviz font configurable

Alternative to PR ##76776.

To change the graphviz output to use an alternative `fontname` value,
add a command line option like: `rustc --graphviz-font=monospace`.

Author: richkadel

compiler/rustc_graphviz/src/lib.rs

@@ -591,14 +591,14 @@ pub trait GraphWalk<'a> {
     fn target(&'a self, edge: &Self::Edge) -> Self::Node;
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug)]
 pub enum RenderOption {
     NoEdgeLabels,
     NoNodeLabels,
     NoEdgeStyles,
     NoNodeStyles,
 
-    Monospace,
+    Fontname(String),
     DarkTheme,
 }
 
@@ -633,11 +633,14 @@ where
     // Global graph properties
     let mut graph_attrs = Vec::new();
     let mut content_attrs = Vec::new();
-    if options.contains(&RenderOption::Monospace) {
-        let font = r#"fontname="Courier, monospace""#;
-        graph_attrs.push(font);
-        content_attrs.push(font);
-    };
+    let font;
+    if let Some(fontname) = options.iter().find_map(|option| {
+        if let RenderOption::Fontname(fontname) = option { Some(fontname) } else { None }
+    }) {
+        font = format!(r#"fontname="{}""#, fontname);
+        graph_attrs.push(&font[..]);
+        content_attrs.push(&font[..]);
+    }
     if options.contains(&RenderOption::DarkTheme) {
         graph_attrs.push(r#"bgcolor="black""#);
         content_attrs.push(r#"color="white""#);

compiler/rustc_mir/src/dataflow/framework/engine.rs

@@ -306,7 +306,8 @@ where
     let mut buf = Vec::new();
 
     let graphviz = graphviz::Formatter::new(body, def_id, results, style);
-    let mut render_opts = vec![dot::RenderOption::Monospace];
+    let mut render_opts =
+        vec![dot::RenderOption::Fontname(tcx.sess.opts.debugging_opts.graphviz_font.clone())];
     if tcx.sess.opts.debugging_opts.graphviz_dark_mode {
         render_opts.push(dot::RenderOption::DarkTheme);
     }

compiler/rustc_mir/src/util/graphviz.rs

@@ -55,9 +55,9 @@ where
     writeln!(w, "{} {}Mir_{} {{", kind, cluster, def_name)?;
 
     // Global graph properties
-    let font = r#"fontname="Courier, monospace""#;
-    let mut graph_attrs = vec![font];
-    let mut content_attrs = vec![font];
+    let font = format!(r#"fontname="{}""#, tcx.sess.opts.debugging_opts.graphviz_font);
+    let mut graph_attrs = vec![&font[..]];
+    let mut content_attrs = vec![&font[..]];
 
     let dark_mode = tcx.sess.opts.debugging_opts.graphviz_dark_mode;
     if dark_mode {

compiler/rustc_session/src/options.rs

@@ -909,6 +909,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "set the optimization fuel quota for a crate"),
     graphviz_dark_mode: bool = (false, parse_bool, [UNTRACKED],
         "use dark-themed colors in graphviz output (default: no)"),
+    graphviz_font: String = ("Courier, monospace".to_string(), parse_string, [UNTRACKED],
+        "use the given `fontname` in graphviz output (default: `Courier, monospace`)"),
     hir_stats: bool = (false, parse_bool, [UNTRACKED],
         "print some statistics about AST and HIR (default: no)"),
     human_readable_cgu_names: bool = (false, parse_bool, [TRACKED],