Standard contracts not fully rebuilt when a contract is removed

[Darion Cassel]

Issue

If a contract is fully removed from the standard contracts foreign_contracts file, after rebuilding standard contracts, the results of MIRAI's analysis seem to indicate that the contract is still there.

Steps to Reproduce

This example is done on the move-binary-format crate (https://github.com/darioncassel/libra/tree/main/language/move-binary-format). Before any of the steps below are followed, the function verify_impl does not have unsatisfied preconditions, but analysis of it may time out.

1. Add contract with a known-false precondition.

--- a/standard_contracts/src/foreign_contracts.rs
+++ b/standard_contracts/src/foreign_contracts.rs
@@ -3735,6 +3735,21 @@ pub mod move_binary_format {
             }
         }
     }
+
+    pub mod check_bounds {
+        pub mod implement {
+            pub struct PartialVMResult<T> {
+                _result: T,
+            }
+    
+            pub struct BoundsChecker {}
+    
+            pub fn verify_impl(_self: &mut BoundsChecker) -> PartialVMResult<()> {
+                precondition!(false);
+                result!()
+            }
+        }
+    }
 }

2. Rebuild standard contracts and install MIRAI.

./rebuild_std.sh
./install_mirai.sh

2. Run analysis on language/move-binary-format/ from fully clean state.

cargo clean
RUSTFLAGS="-Z always_encode_mir" cargo build
touch src/lib.rs && RUSTFLAGS="-Z always_encode_mir" RUSTC_WRAPPER=mirai MIRAI_FLAGS="--diag=verify" cargo build

Result: The contract is reached and found to be unsatisfied as expected.

warning: unsatisfied precondition, defined in standard_contracts/src/foreign_contracts.rs:3748:17: 3748:38
  --> language/move-binary-format/src/check_bounds.rs:86:9
   |
86 |         bounds_check.verify_impl()
   |         ^^^^^^^^^^^^^^^^^^

3. Remove that contract, rebuild standard contracts, and install MIRAI.

./rebuild_std.sh
./install_mirai.sh

4. Run the analysis.

cargo clean
RUSTFLAGS="-Z always_encode_mir" cargo build
touch src/lib.rs && RUSTFLAGS="-Z always_encode_mir" RUSTC_WRAPPER=mirai MIRAI_FLAGS="--diag=verify" cargo build

Result:

warning: unsatisfied precondition, defined in standard_contracts/src/foreign_contracts.rs:3748:17: 3748:38
  --> language/move-binary-format/src/check_bounds.rs:55:9
   |
55 |         bounds_check.verify_impl()?;
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^

Expected Behavior

There should not be an unsatisfied precondition for verify_impl at step 4 because the contract was removed in step 3.

Actual Results

The unsatisfied precondition (precondition!(false)) results in a warning that still references foreign_contracts.rs even though the contract was removed.

Environment

Rust version (rustc --version): rustc 1.55.0-nightly (7c3872e6b 2021-06-24)

[Herman Venter]

I find myself wondering if the second call to ./install_mirai.sh does a rebuild of MIRAI. I.e. perhaps cargo install does not figure out that updating binaries/summary_store.tar invalidates the current binary for MIRAI and so the second call to cargo install just uses the same bits as the first call.

[Darion Cassel]

Perhaps, but I think that is less likely because if I use git to manually revert just the summary_store.tar file and then follow that same rebuild process (including install_mirai.sh) the contract no longer shows up in the analysis.