Add support for Column annotations for MockProver debugging

halo2_proofs/src/circuit.rs

@@ -206,6 +206,20 @@ impl<'r, F: Field> Region<'r, F> {
             .enable_selector(&|| annotation().into(), selector, offset)
     }
 
+    /// Allows the circuit implementor to name/annotate a Column within a Region context.
+    ///
+    /// This is useful in order to improve the amount of information that `prover.verify()`
+    /// and `prover.assert_satisfied()` can provide.
+    pub fn name_column<A, AR, T>(&mut self, annotation: A, column: T)
+    where
+        A: Fn() -> AR,
+        AR: Into<String>,
+        T: Into<Column<Any>>,
+    {
+        self.region
+            .name_column(&|| annotation().into(), column.into());
+    }
+
     /// Assign an advice column value (witness).
     ///
     /// Even though `to` has `FnMut` bounds, it is guaranteed to be called at most once.

halo2_proofs/src/circuit/floor_planner/single_pass.rs

@@ -279,6 +279,14 @@ impl<'r, 'a, F: Field, CS: Assignment<F> + 'a> RegionLayouter<F>
         )
     }
 
+    fn name_column<'v>(
+        &'v mut self,
+        annotation: &'v (dyn Fn() -> String + 'v),
+        column: Column<Any>,
+    ) {
+        self.layouter.cs.annotate_column(annotation, column);
+    }
+
     fn assign_advice<'v>(
         &'v mut self,
         annotation: &'v (dyn Fn() -> String + 'v),

halo2_proofs/src/circuit/floor_planner/v1.rs

@@ -481,6 +481,14 @@ impl<'r, 'a, F: Field, CS: Assignment<F> + 'a> RegionLayouter<F> for V1Region<'r
         Ok(())
     }
 
+    fn name_column<'v>(
+        &'v mut self,
+        _annotation: &'v (dyn Fn() -> String + 'v),
+        _column: Column<Any>,
+    ) {
+        // Do nothing
+    }
+
     fn constrain_equal(&mut self, left: Cell, right: Cell) -> Result<(), Error> {
         self.plan.cs.copy(
             left.column,

halo2_proofs/src/circuit/layouter.rs

@@ -48,6 +48,16 @@ pub trait RegionLayouter<F: Field>: fmt::Debug {
         offset: usize,
     ) -> Result<(), Error>;
 
+    /// Allows the circuit implementor to name/annotate a Column within a Region context.
+    ///
+    /// This is useful in order to improve the amount of information that `prover.verify()`
+    /// and `prover.assert_satisfied()` can provide.
+    fn name_column<'v>(
+        &'v mut self,
+        annotation: &'v (dyn Fn() -> String + 'v),
+        column: Column<Any>,
+    );
+
     /// Assign an advice column value (witness)
     fn assign_advice<'v>(
         &'v mut self,
@@ -275,6 +285,14 @@ impl<F: Field> RegionLayouter<F> for RegionShape {
         })
     }
 
+    fn name_column<'v>(
+        &'v mut self,
+        _annotation: &'v (dyn Fn() -> String + 'v),
+        _column: Column<Any>,
+    ) {
+        // Do nothing
+    }
+
     fn constrain_constant(&mut self, _cell: Cell, _constant: Assigned<F>) -> Result<(), Error> {
         // Global constants don't affect the region shape.
         Ok(())