[chore] add crate prefix to type_ids (#218)

* chore: add crate prefix to `type_id`s

* fix: module_path! url

* chore: add type_id warning to `Context::new` and `ContextCell::new`

halo2-base/README.md

@@ -69,7 +69,8 @@ During `synthesize()`, the advice values of all `Context`s are concatenated into
 
 For parallel witness generation, multiple `Context`s are created for each parallel operation. After parallel witness generation, these `Context`'s are combined to form a single "virtual column" as above. Note that while the witness generation can be multi-threaded, the ordering of the contents in each `Context`, and the order of the `Context`s themselves, must be deterministic.
 
-**Warning:** If you create your own `Context` in a new virtual region not provided by our libraries, you must ensure that the `type_id: &str` of the context is a globally unique identifier for the virtual region, distinct from the other `type_id` strings used to identify other virtual regions. In the future we will introduce a macro to check this uniqueness at compile time.
+**Warning:** If you create your own `Context` in a new virtual region not provided by our libraries, you must ensure that the `type_id: &str` of the context is a globally unique identifier for the virtual region, distinct from the other `type_id` strings used to identify other virtual regions. We suggest that you either include your crate name as a prefix in the `type_id` or use [`module_path!`](https://doc.rust-lang.org/std/macro.module_path.html) to generate a prefix.
+In the future we will introduce a macro to check this uniqueness at compile time.
 
 ### [**AssignedValue**](./src/lib.rs):
 

halo2-base/src/gates/flex_gate/threads/single_phase.rs

@@ -113,9 +113,9 @@ impl<F: ScalarField> SinglePhaseCoreManager<F> {
     /// A distinct tag for this particular type of virtual manager, which is different for each phase.
     pub fn type_of(&self) -> &'static str {
         match self.phase {
-            0 => "SinglePhaseCoreManager: FirstPhase",
-            1 => "SinglePhaseCoreManager: SecondPhase",
-            2 => "SinglePhaseCoreManager: ThirdPhase",
+            0 => "halo2-base:SinglePhaseCoreManager:FirstPhase",
+            1 => "halo2-base:SinglePhaseCoreManager:SecondPhase",
+            2 => "halo2-base:SinglePhaseCoreManager:ThirdPhase",
             _ => panic!("Unsupported phase"),
         }
     }

halo2-base/src/lib.rs

@@ -120,6 +120,9 @@ pub struct ContextCell {
 
 impl ContextCell {
     /// Creates a new [ContextCell] with the given `type_id`, `context_id`, and `offset`.
+    ///
+    /// **Warning:** If you create your own `Context` in a new virtual region not provided by our libraries, you must ensure that the `type_id: &str` of the context is a globally unique identifier for the virtual region, distinct from the other `type_id` strings used to identify other virtual regions. We suggest that you either include your crate name as a prefix in the `type_id` or use [`module_path!`](https://doc.rust-lang.org/std/macro.module_path.html) to generate a prefix.
+    /// In the future we will introduce a macro to check this uniqueness at compile time.
     pub fn new(type_id: &'static str, context_id: usize, offset: usize) -> Self {
         Self { type_id, context_id, offset }
     }
@@ -203,6 +206,9 @@ impl<F: ScalarField> Context<F> {
     /// Creates a new [Context] with the given `context_id` and witness generation enabled/disabled by the `witness_gen_only` flag.
     /// * `witness_gen_only`: flag to determine whether public key generation or only witness generation is being performed.
     /// * `context_id`: identifier to reference advice cells from this [Context] later.
+    ///
+    /// **Warning:** If you create your own `Context` in a new virtual region not provided by our libraries, you must ensure that the `type_id: &str` of the context is a globally unique identifier for the virtual region, distinct from the other `type_id` strings used to identify other virtual regions. We suggest that you either include your crate name as a prefix in the `type_id` or use [`module_path!`](https://doc.rust-lang.org/std/macro.module_path.html) to generate a prefix.
+    /// In the future we will introduce a macro to check this uniqueness at compile time.
     pub fn new(
         witness_gen_only: bool,
         phase: usize,

halo2-base/src/virtual_region/copy_constraints.rs

@@ -86,7 +86,8 @@ impl<F: Field + Ord> CopyConstraintManager<F> {
     }
 
     fn load_external_cell_impl(&mut self, cell: Option<Cell>) -> ContextCell {
-        let context_cell = ContextCell::new("External Raw Halo2 Cell", 0, self.external_cell_count);
+        let context_cell =
+            ContextCell::new("halo2-base:External Raw Halo2 Cell", 0, self.external_cell_count);
         self.external_cell_count += 1;
         if let Some(cell) = cell {
             self.assigned_advices.insert(context_cell, cell);