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Mirror the regular contract-storage design (the parameterised pointer type storage(a) and its classes) for EVM transient storage, using the tload/tstore opcodes instead of sload/sstore. The pointer type is named tstorage(a) so that `transient` stays free to become a storage-location keyword. Layout metadata is location-independent, so StorageSize and the generic CanStore/Assign/LVA/RVA/IdxAccess/mapping machinery are reused from std rather than duplicated. New pieces are the parts that actually touch the opcodes: the TransientType class and its value-type instances, CanStore instances for tstorage value types, mappings, and strings/bytes, the byte-array helpers, and the readTransient / ltidx / rtidx accessors. Add a transient counter dispatch example and register it in the suite. Assisted-By: Claude Opus 4.8 <noreply@anthropic.com>
Introduce a `transient` keyword and the contract-field syntax `name : transient T`, which marks a field as living in EVM transient storage. A StorageLocation marker (Storage | Transient) is threaded from the surface AST through name resolution into the resolved AST and on to the field-access desugarer. Lowering is not yet implemented: the field-access desugarer rejects transient fields with a clear "not implemented yet" message. So the syntax parses and type-resolves but fails at desugaring, which is the seam where transient lowering (tstorage-based CStructField instances) will later plug in. Because `transient` is now reserved, the standard-library module can no longer be imported as `std.transient`; rename it to `std.tstorage` (the type it provides is already `tstorage`) and update the counter example. Parser tests cover both plain and initialized transient fields; test/examples/dispatch/transient_field.solc demonstrates the end-to-end syntax (intentionally unregistered, as it fails at desugaring). Assisted-By: Claude Opus 4.8 <noreply@anthropic.com>
FieldAccess now translates a `transient` field of type t to tstorage(t) in its generated CStructField instance (a regular field still maps to storage(t)), replacing the previous "not implemented" desugaring error. The storage-kind distinction is an output of the CStructField context, not the MemberAccessProxy main type, so a second location-specific LVA/RVA instance would overlap the storage one. Instead, generalize the std LVA/RVA instances to abstract over the reference constructor: a `refType` bound by CStructField(refType, off), refType:Typedef(word) and refType:CanStore(loadType), built from the slot offset via Typedef.abs. FieldAccess selects the location purely by the refType it emits. test/examples/dispatch/transient_field.solc now compiles and is a registered dispatch test; set/get on the transient field lower to tstore/tload (verified: a write+read in one call round-trips). Assisted-By: Claude Opus 4.8 <noreply@anthropic.com>
The dispatch test only compiles the contract; this adds an executing
end-to-end test via the testrunner/contest path that asserts EVM
behaviour.
Add a `roundtrip` method (write then read the transient field in one
call) and transient_field.json with three assertions:
- roundtrip(77) returns 77 (tstore then tload within one tx);
- set(99) succeeds;
- a later get() returns 0, because transient storage is cleared at the
end of each transaction (EIP-1153).
The last assertion is what distinguishes transient from persistent
storage: if the field were lowered to sstore/sload, get() would return
99 and the test would fail. Wired into run_contests.sh (run by
`nix flake check`).
Assisted-By: Claude Opus 4.8 <noreply@anthropic.com>
6 tasks
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Adds support for EVM transient storage, mirroring the existing persistent-storage design.
What's included:
tstorage(a)type andTransientTypeclass (backed bytload/tstore), withCanStoreinstances for scalars, mappings, strings, and bytes. Layout metadata (StorageSize) is reused from std, since transient and persistent storage share the same slot layout.transientkeyword - contract fields can now be declared name : transient T to place them in transient storage. AStorageLocationmarker (Storage | Transient) threads through the AST from parser to desugarer.FieldAccesslowers a transient field totstorage(t)instead ofstorage(t). The std LVA/RVA contract-field instances were generalized over the reference type so a single instance serves both locations (a second instance would overlap onMemberAccessProxy).transient_field.{solc,json}verifies the semantics via thetestrunner: a write+read within one call returns the value, while a value written in one transaction reads back as 0 in a later one, confirming per-transaction clearing.Fields default to persistent storage, so existing contracts are unaffected.