From 504f0aaf15ce8baa2886a258faf56592495bbc51 Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Thu, 4 Jul 2019 21:00:44 +0100
Subject: [PATCH] rust: make ExecutionContext optional in EvmcVm.execute()

---
 bindings/rust/evmc-declare-tests/src/lib.rs |  2 +-
 bindings/rust/evmc-declare/src/lib.rs       | 16 +++++++++-------
 bindings/rust/evmc-vm/src/container.rs      |  2 +-
 bindings/rust/evmc-vm/src/lib.rs            |  2 +-
 examples/example-rust-vm/src/lib.rs         |  2 +-
 5 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/bindings/rust/evmc-declare-tests/src/lib.rs b/bindings/rust/evmc-declare-tests/src/lib.rs
index 38fd2f3e7..d95a0f7e3 100644
--- a/bindings/rust/evmc-declare-tests/src/lib.rs
+++ b/bindings/rust/evmc-declare-tests/src/lib.rs
@@ -21,7 +21,7 @@ impl EvmcVm for FooVM {
         &self,
         _code: &[u8],
         _message: &ExecutionMessage,
-        _context: &ExecutionContext,
+        _context: Option<&ExecutionContext>,
     ) -> ExecutionResult {
         ExecutionResult::success(1337, None)
     }
diff --git a/bindings/rust/evmc-declare/src/lib.rs b/bindings/rust/evmc-declare/src/lib.rs
index c74527816..ca507eda1 100644
--- a/bindings/rust/evmc-declare/src/lib.rs
+++ b/bindings/rust/evmc-declare/src/lib.rs
@@ -22,14 +22,14 @@
 //!             ExampleVM {}
 //!     }
 //!
-//!     fn execute(&self, code: &[u8], message: &evmc_vm::ExecutionMessage, context: &evmc_vm::ExecutionContext) -> evmc_vm::ExecutionResult {
+//!     fn execute(&self, code: &[u8], message: &evmc_vm::ExecutionMessage, context: Option<&evmc_vm::ExecutionContext>) -> evmc_vm::ExecutionResult {
 //!             evmc_vm::ExecutionResult::success(1337, None)
 //!     }
 //! }
 //! ```
 
 // Set a higher recursion limit because parsing certain token trees might fail with the default of 64.
-#![recursion_limit = "128"]
+#![recursion_limit = "160"]
 
 extern crate proc_macro;
 
@@ -338,14 +338,16 @@ fn build_execute_fn(names: &VMNameSet) -> proc_macro2::TokenStream {
             use evmc_vm::EvmcVm;
 
             assert!(!instance.is_null());
-            // TODO: context is optional in case of the "precompiles" capability
-            assert!(!context.is_null());
             assert!(!msg.is_null());
 
             let execution_message: ::evmc_vm::ExecutionMessage = unsafe { msg.as_ref().unwrap().into() };
 
-            let execution_context = unsafe {
-                ::evmc_vm::ExecutionContext::new(context.as_mut().expect("EVMC context is null"))
+            let execution_context: Option<::evmc_vm::ExecutionContext> = if context.is_null() {
+                None
+            } else {
+                Some(unsafe {
+                    ::evmc_vm::ExecutionContext::new(context.as_mut().expect("EVMC context is null"))
+                })
             };
 
             let empty_code = [0u8;0];
@@ -363,7 +365,7 @@ fn build_execute_fn(names: &VMNameSet) -> proc_macro2::TokenStream {
             };
 
             let result = ::std::panic::catch_unwind(|| {
-                container.execute(code_ref, &execution_message, &execution_context)
+                container.execute(code_ref, &execution_message, execution_context.as_ref())
             });
 
             let result = if result.is_err() {
diff --git a/bindings/rust/evmc-vm/src/container.rs b/bindings/rust/evmc-vm/src/container.rs
index aa22d3523..54c8eaf97 100644
--- a/bindings/rust/evmc-vm/src/container.rs
+++ b/bindings/rust/evmc-vm/src/container.rs
@@ -61,7 +61,7 @@ mod tests {
             &self,
             _code: &[u8],
             _message: &ExecutionMessage,
-            _context: &ExecutionContext,
+            _context: Option<&ExecutionContext>,
         ) -> ExecutionResult {
             ExecutionResult::failure()
         }
diff --git a/bindings/rust/evmc-vm/src/lib.rs b/bindings/rust/evmc-vm/src/lib.rs
index 682dea09e..c708b1304 100644
--- a/bindings/rust/evmc-vm/src/lib.rs
+++ b/bindings/rust/evmc-vm/src/lib.rs
@@ -21,7 +21,7 @@ pub trait EvmcVm {
         &self,
         code: &[u8],
         message: &ExecutionMessage,
-        context: &ExecutionContext,
+        context: Option<&ExecutionContext>,
     ) -> ExecutionResult;
 }
 
diff --git a/examples/example-rust-vm/src/lib.rs b/examples/example-rust-vm/src/lib.rs
index e48ab7194..c226e7c4a 100644
--- a/examples/example-rust-vm/src/lib.rs
+++ b/examples/example-rust-vm/src/lib.rs
@@ -18,7 +18,7 @@ impl EvmcVm for ExampleRustVM {
         &self,
         _code: &[u8],
         message: &ExecutionMessage,
-        context: &ExecutionContext,
+        context: Option<&ExecutionContext>,
     ) -> ExecutionResult {
         let is_create = message.kind() == evmc_sys::evmc_call_kind::EVMC_CREATE;