3.20: Shielded storage opcodes are emitted for pre-Mercury EVM versions#201
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cdrappi merged 2 commits intozellic-auditfrom Feb 16, 2026
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3.20: Shielded storage opcodes are emitted for pre-Mercury EVM versions#201cdrappi merged 2 commits intozellic-auditfrom
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Add comprehensive test coverage for shielded type validation across different EVM versions. Tests verify that shielded types are rejected on pre-Mercury EVM versions with error 9978. State storage variables: - shielded_storage_evm_version_paris.sol: Single suint256 on Paris - shielded_storage_evm_version_cancun.sol: Multiple shielded types on Cancun - shielded_storage_struct_evm_version.sol: Struct containing shielded type - shielded_storage_sbytes_evm_version.sol: Shielded byte array Other variable contexts: - shielded_local_variable_evm_version.sol: Local function variable - shielded_immutable_evm_version.sol: Immutable variable (error 7491) - shielded_constant_evm_version.sol: Constant variable (error 7491) Positive test: - shielded_storage_evm_version_mercury.sol: Confirms Mercury support All tests run with both legacy and via-IR pipelines (compileViaYul: true). Note: Immutable and constant tests expect error 7491 (existing validation) rather than 9978, as shielded types cannot be immutable or constant.
Prevent emission of CLOAD/CSTORE opcodes on pre-Mercury EVM versions when using shielded types (suint, sbool, saddress, sbytes) in ANY context. ## Problem Compiling with --evm-version paris (or any pre-Mercury version) incorrectly emitted cload/cstore opcodes for shielded types, causing "invalid opcode" runtime errors on pre-Mercury VMs. ## Solution: Two-Layer Defense ### Layer 1: Type Checker (libsolidity/analysis/TypeChecker.cpp) Add comprehensive early validation in visit(VariableDeclaration) to reject ALL uses of shielded types on pre-Mercury versions: **Checked contexts:** - State storage variables (regular, non-constant, non-immutable) - Local storage references/pointers - Local value-type variables (stack/memory) - Immutable variables (value types only) - Constant variables **Safety considerations:** - For immutables: only check if value type (non-value types already error at line 532) - For constants: always safe (must be value types) - For state variables: always safe (storage location guaranteed) - For local storage: safe (storage location) - For local value types: safe (no nested mapping issues) Error 9978 provides actionable message guiding users to --evm-version mercury. ### Layer 2: Codegen Assertions **Legacy Pipeline (libsolidity/codegen/LValue.cpp)** Add 6 defensive assertions to catch any cases that slip through: - GenericStorageItem::retrieveValue() - line 237 - GenericStorageItem::storeValue() - line 310 - GenericStorageItem::setToZero() - line 521 - StorageByteArrayElement::retrieveValue() - line 569 - StorageByteArrayElement::storeValue() - line 584 - StorageByteArrayElement::setToZero() - line 614 **Via-IR Pipeline (libsolidity/codegen/YulUtilFunctions.cpp)** Add assertions in key functions: - readFromStorageValueType() - line 2864 - resizeDynamicByteArrayFunction() - line 1448 - storageArrayPopFunction() - line 1648 - storageArrayPushZeroFunction() - line 1799 ## Coverage - All variable contexts (state, local, immutable, constant) - Arrays/structs containing shielded types (containsShieldedType check) - Shielded byte arrays (StorageByteArrayElement handlers) - Both legacy and via-IR compilation pipelines - All shielded type categories (suint, sbool, saddress, sbytes)
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