Layout root graph

[sbillig]

Replaces layout-hole handling type/provenance-based layout hole (aka const hole, eg const SALT: usize = _ ) inference to an explicit layout-root graph and layout-evidence ABI.

Each source layout parameter now has a stable identity, and each structural occurrence receives its own
slot assignment. Evidence is carried through HIR and MIR instead of being reconstructed later from types or provenance.

Bug fixes

• Fixed issue where repeated instances of a hole-bearing type within a single contract field would be assigned the same slot number. Eg maps: (StorageMap<u256, u256>, StorageMap<u256, u256>).
• Reserves explicit layout parameters before assigning inferred ones. Mixed layouts such as an explicit SALT = 1 followed by inferred maps can no longer collide, while intentionally duplicated explicit parameters still
  share.
• Correctly lays out static arrays of hole-bearing types, including nested and multidimensional arrays, using
  checked indexed root families.
• Preserves runtime bounds checks for dynamically indexed layout-only or zero-sized array elements.
• Rejects unresolved, ambiguous, overflowing, cyclic, or otherwise invalid layouts atomically instead of
  producing provisional or aliased layouts.

Storage layout LSP hover

Contract-name hover now shows the complete contract layout, grouped under Storage, Transient Storage, Immutable (code). Example:

struct CounterStore { global: u256, counts: StorageMap<Address, u256> }

// The contract itself: declares its storage and handles messages.
pub contract Counter uses (ctx: Ctx) {
    mut store: CounterStore,
    mut table: [[u256; 2]; 4],
    mut baz: Mutex<StorageMap<u256, u256, 0>,

shows:

Storage
  0: baz.value.SALT (explicit parameter, u256)
  1: store.global (inline field, u256)
  2: store.counts.SALT (inferred parameter, u256)
  3 + i0*2 + i1 (i0: 0..4, i1: 0..2): table[i0][i1] (inline field, u256)
  
Transient Storage
  0: baz.lock.SLOT (inferred parameter, u256)

Field hover shows the entries belonging to that field. Array layouts include their index formula and
dimensions, and invalid or blocked layouts explain why no assignment is available.

[chatgpt-codex-connector]

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[sbillig]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Swish!

Reviewed commit: 4379625361

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".