Add CEI pattern static analysis (#3168)

CEI stands for "Checks, Effects, Interactions". We check no storage
reads/writes (effects) occur after calling external contracts
(interaction). See this [blog
post](https://fravoll.github.io/solidity-patterns/checks_effects_interactions.html)
and [this
blogpost](https://chainsecurity.com/curve-lp-oracle-manipulation-post-mortem)
for more detail.

TODOs:
- [x] analyze libraries, scripts, and predicates (only contracts are
analyzed at the moment)
- [x] process assembly blocks
- [x] what is the effects of the `__revert` intrinsic
- [x] Treat nested code blocks
- [x] more tests
  * [x] Tests using `storage.var = ...`
  * [x] Tests using `asm` blocks directly
  * [x] Tests using complex control flow
* [x] Tests having multiple contract calls or multiple storage writes in
various scenarios
* [ ] Tests with nested code blocks (there is a very simple test, this
needs more testing in a separate PR)
- [x] check for storage reads after interaction 
   * [x] Storage read intrinsics
   * [x] `StorageAccess` expressions
   * [x] `asm` blocks using `srw` or `srwq`
* [x] `asm` blocks using
[`bal`](https://github.com/FuelLabs/fuel-specs/blob/master/specs/vm/instruction_set.md#bal-balance-of-contract-id)
because `bal` actually reads from storage
- [x] ~~CLI option or attribute to control the warnings~~ (an internal
discussion showed that we cannot do this at the moment, I guess this
should be handled as a separate issue)
- [ ] open an issue about unification of the currently existing storage
annotation checks and effects inference in this PR

close #10

Co-authored-by: Mohammad Fawaz <mohammadfawaz89@gmail.com>

sway-core/src/lib.rs

@@ -217,6 +217,11 @@ pub fn parsed_to_ast(
         errors.push(e);
     }
 
+    // CEI pattern analysis
+    let cei_analysis_warnings =
+        semantic_analysis::cei_pattern_analysis::analyze_program(&typed_program);
+    warnings.extend(cei_analysis_warnings);
+
     // Check that all storage initializers can be evaluated at compile time.
     let typed_wiss_res = typed_program.get_typed_program_with_initialized_storage_slots(
         &mut ctx,

sway-core/src/semantic_analysis.rs

@@ -1,5 +1,6 @@
 //! Type checking for Sway.
 pub mod ast_node;
+pub(crate) mod cei_pattern_analysis;
 mod module;
 pub mod namespace;
 mod node_dependencies;