verifyProof function as view as it does not modify storage (#20)

* fix: verifyProof function as view as it does not modify storage

* added instructions to run examples and tests, noted cargo version issue

* fix: add rust-toolchain configuration file to specify rust toolchain version to be used

* ci: install [email protected] for rust 1.77.0 compatibility

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
           cache-on-failure: true
 
       - name: Install solc
-        run: (hash svm 2>/dev/null || cargo install svm-rs) && svm install 0.8.21 && solc --version
+        run: (hash svm 2>/dev/null || cargo install svm-rs@0.5.4) && svm install 0.8.21 && solc --version
 
       - name: Run test
         run: cargo test --workspace --all-features --all-targets -- --nocapture

README.md

@@ -17,6 +17,17 @@ let (verifier_solidity, vk_solidity) = generator.render_separately().unwrap();
 
 Check [`examples/separately.rs`](./examples/separately.rs) for more details.
 
+> [!NOTE]
+> Currently example run only with rust `1.77.0` version due to a `cargo` update ([rust-lang/rust#123285](https://github.com/rust-lang/rust/issues/123285)).
+>
+> The `rust` toolchain version is specified in [rust-toolchain.toml](./rust-toolchain.toml) file.
+
+Run example with the following command:
+
+```bash
+cargo run --all-features --example separately
+```
+
 ### Generate verifier and verifying key in a single solidity contract
 
 ```rust
@@ -32,6 +43,20 @@ let calldata = encode_calldata(vk_address, &proof, &instances);
 
 Note that function selector is already included.
 
+## Test
+
+To run tests, use the following command:
+
+```bash
+cargo test --workspace --all-features --all-targets -- --nocapture
+```
+
+> [!NOTE]
+> Currently tests run only with rust `1.77.0` version due to a `cargo` update ([rust-lang/rust#123285](https://github.com/rust-lang/rust/issues/123285)).
+>
+> The `rust` toolchain version is specified in [rust-toolchain.toml](./rust-toolchain.toml) file.
+
+
 ## Limitations & Caveats
 
 - It only allows circuit with **less or equal than 1 instance column** and **no rotated query to this instance column**.

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.77.0"

templates/Halo2Verifier.sol

@@ -78,7 +78,7 @@ contract Halo2Verifier {
         {%- endmatch %}
         bytes calldata proof,
         uint256[] calldata instances
-    ) public returns (bool) {
+    ) public view returns (bool) {
         assembly {
             // Read EC point (x, y) at (proof_cptr, proof_cptr + 0x20),
             // and check if the point is on affine plane,