Auto merge of #69012 - Dylan-DPC:rollup-13qn0fq, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #68694 (Reduce the number of `RefCell`s in `InferCtxt`.)
 - #68966 (Improve performance of coherence checks)
 - #68976 (Make `num::NonZeroX::new` an unstable `const fn`)
 - #68992 (Correctly parse `mut a @ b`)
 - #69005 (Small graphviz improvements for the new dataflow framework)
 - #69006 (parser: Keep current and previous tokens precisely)

Failed merges:

r? @ghost

Author: bors

src/libcore/num/mod.rs

@@ -69,8 +69,9 @@ assert_eq!(size_of::<Option<core::num::", stringify!($Ty), ">>(), size_of::<", s
 
                 /// Creates a non-zero if the given value is not zero.
                 #[$stability]
+                #[rustc_const_unstable(feature = "const_nonzero_int_methods", issue = "53718")]
                 #[inline]
-                pub fn new(n: $Int) -> Option<Self> {
+                pub const fn new(n: $Int) -> Option<Self> {
                     if n != 0 {
                         // SAFETY: we just checked that there's no `0`
                         Some(unsafe { Self(n) })

src/libgraphviz/lib.rs

@@ -597,6 +597,8 @@ pub enum RenderOption {
     NoNodeLabels,
     NoEdgeStyles,
     NoNodeStyles,
+
+    Monospace,
 }
 
 /// Returns vec holding all the default render options.
@@ -626,6 +628,14 @@ where
     W: Write,
 {
     writeln!(w, "digraph {} {{", g.graph_id().as_slice())?;
+
+    // Global graph properties
+    if options.contains(&RenderOption::Monospace) {
+        writeln!(w, r#"    graph[fontname="monospace"];"#)?;
+        writeln!(w, r#"    node[fontname="monospace"];"#)?;
+        writeln!(w, r#"    edge[fontname="monospace"];"#)?;
+    }
+
     for n in g.nodes().iter() {
         write!(w, "    ")?;
         let id = g.node_id(n);