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hyperpolymathJonathan D.A. Jewellclaude
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ABI: make Idris2 proofs genuinely compile + add machine-checked theorems (#49)
* Add SPDX header to LICENSE and set Cargo.toml license field The governance/licence-consistency check requires an SPDX-License-Identifier header on the LICENSE file and a `license` field in the manifest. The LICENSE body is MPL-2.0 text, so stamp `SPDX-License-Identifier: MPL-2.0` (matching the actual body) and set `license = "MPL-2.0"` (replacing `license-file`). Verified with standards/scripts/check-licence-consistency.sh (passes). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DF9CcCuL4YJoqs26eHsYiA * Fix Idris2 ABI proofs to genuinely compile under Idris2 0.7.0 The src/interface/abi/{Types,Layout,Foreign}.idr files were scaffolded from a template and never compiler-checked. This makes the formal ABI proofs actually typecheck and verify, mirroring the merged iseriser reference. Fixes: - DecEq for ConsentType, WCAGLevel, Result: replaced the non-compiling `decEq _ _ = No absurd` catch-all with explicit off-diagonal cases `decEq X Y = No (\case Refl impossible)`. - createHandle: solve the {auto 0 nonNull : So (ptr /= 0)} obligation via `choose (ptr /= 0)` instead of leaving the auto proof unsolved. - paddingFor: use `minus alignment (mod offset alignment)` (Nat has no Neg). - checkCABI: implemented a sound decision procedure (decDivides + decFieldsAligned) building real FieldsAligned witnesses; removed the ?fieldsAlignedProof hole. - offsetInBounds: changed the unsound universally-quantified `So (...)` return type to `Maybe (So (offset+size <= totalSize))` via choose. - thisPlatform: replaced the %runElab stub (needs ElabReflection) with `Linux`. - Concrete StructLayout values now supply erased auto-implicit proofs explicitly ({sizeCorrect = Oh}, {aligned = DivideBy k Refl}). - Pre-existing scaffold bugs: declared FormatKind before its use in I18nHook; fixed CPtr (Data.Bits.Bits is an interface, not Nat -> Type). - Renamed Vect binder n -> k to avoid implicit-bind/shadowing warnings. Buildability: - Moved flat files to src/interface/abi/Wokelangiser/ABI/{Types,Layout,Foreign}.idr so file paths match the Wokelangiser.ABI.* namespaces. - Added src/interface/abi/wokelangiser-abi.ipkg. New theorems (src/interface/abi/Wokelangiser/ABI/Proofs.idr): - consentRecordCompliant, accessibilityRecordCompliant, i18nRecordCompliant: CABICompliant witnesses built directly from per-field DivideBy proofs. - okIsZero, i18nErrorIsSeven: pin the result-code encoding. - auditTrailRoundTrips, aaaRoundTrips: encoding round-trips. `cd src/interface/abi && idris2 --build wokelangiser-abi.ipkg` exits 0 with zero errors and zero warnings. Added **/build/, *.ttc, *.ttm to .gitignore; no build artifacts committed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DF9CcCuL4YJoqs26eHsYiA --------- Co-authored-by: Jonathan D.A. Jewell <paraordinate@yahoo.co.uk> Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
1 parent 21400aa commit 2c12d32

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‎.gitignore‎

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@@ -18,6 +18,11 @@ Thumbs.db
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/dist/
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/out/
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# Idris2 build artifacts
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**/build/
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*.ttc
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*.ttm
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# Dependencies
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/node_modules/
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/vendor/

src/interface/abi/Foreign.idr renamed to src/interface/abi/Wokelangiser/ABI/Foreign.idr

File renamed without changes.

src/interface/abi/Layout.idr renamed to src/interface/abi/Wokelangiser/ABI/Layout.idr

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@@ -14,37 +14,56 @@ module Wokelangiser.ABI.Layout
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import Wokelangiser.ABI.Types
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import Data.Vect
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import Data.So
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import Data.Nat
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import Decidable.Equality
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%default total
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--------------------------------------------------------------------------------
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-- Alignment Utilities
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--------------------------------------------------------------------------------
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24-
||| Calculate padding needed for alignment
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||| Calculate padding needed for alignment. Uses `minus` (Nat subtraction)
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||| because `Nat` has no `Neg` instance — `alignment - (...)` did not compile.
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public export
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paddingFor : (offset : Nat) -> (alignment : Nat) -> Nat
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paddingFor offset alignment =
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if offset `mod` alignment == 0
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then 0
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else alignment - (offset `mod` alignment)
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else minus alignment (offset `mod` alignment)
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||| Proof that alignment divides aligned size
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||| Proof that alignment divides aligned size: `m = k * n`.
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public export
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data Divides : Nat -> Nat -> Type where
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DivideBy : (k : Nat) -> {n : Nat} -> {m : Nat} -> (m = k * n) -> Divides n m
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||| Sound decision procedure for divisibility. Returns a genuine
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||| `Divides n m` witness when `n` evenly divides `m`, otherwise Nothing.
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||| Division by zero is undecidable here and yields Nothing.
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public export
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decDivides : (n : Nat) -> (m : Nat) -> Maybe (Divides n m)
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decDivides Z _ = Nothing
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decDivides (S k) m =
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let q = m `div` (S k) in
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case decEq m (q * (S k)) of
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Yes prf => Just (DivideBy q prf)
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No _ => Nothing
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||| Round up to next alignment boundary
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public export
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alignUp : (size : Nat) -> (alignment : Nat) -> Nat
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alignUp size alignment =
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size + paddingFor size alignment
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||| Proof that alignUp produces aligned result
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||| Sound divisibility check for an aligned size. The general theorem
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||| "alignUp size align is always divisible by align" needs div/mod lemmas
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||| from Data.Nat and is tracked as residual proof work; here we *decide* it
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||| via `decDivides`, which returns a genuine witness when it holds. For the
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||| concrete ABI layouts below, divisibility is proven outright (`DivideBy`).
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public export
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alignUpCorrect : (size : Nat) -> (align : Nat) -> (align > 0) -> Divides align (alignUp size align)
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alignUpCorrect size align prf =
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DivideBy ((size + paddingFor size align) `div` align) Refl
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alignUpDivides : (size : Nat) -> (align : Nat) ->
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Maybe (Divides align (alignUp size align))
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alignUpDivides size align = decDivides align (alignUp size align)
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--------------------------------------------------------------------------------
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-- Struct Field Layout
@@ -64,7 +83,7 @@ public export
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nextFieldOffset : Field -> Nat
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nextFieldOffset f = alignUp (f.offset + f.size) f.alignment
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67-
||| A struct layout is a list of fields with proofs
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||| A struct layout is a vector of fields with size and alignment proofs.
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public export
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record StructLayout where
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constructor MkStructLayout
@@ -76,7 +95,7 @@ record StructLayout where
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||| Calculate total struct size with padding
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public export
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calcStructSize : Vect n Field -> Nat -> Nat
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calcStructSize : Vect k Field -> Nat -> Nat
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calcStructSize [] align = 0
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calcStructSize (f :: fs) align =
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let lastOffset = foldl (\acc, field => nextFieldOffset field) f.offset fs
@@ -85,58 +104,48 @@ calcStructSize (f :: fs) align =
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||| Proof that field offsets are correctly aligned
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public export
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data FieldsAligned : Vect n Field -> Type where
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data FieldsAligned : Vect k Field -> Type where
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NoFields : FieldsAligned []
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ConsField :
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(f : Field) ->
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(rest : Vect n Field) ->
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(rest : Vect k Field) ->
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Divides f.alignment f.offset ->
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FieldsAligned rest ->
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FieldsAligned (f :: rest)
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||| Verify a struct layout is valid
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public export
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verifyLayout : (fields : Vect n Field) -> (align : Nat) -> Either String StructLayout
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verifyLayout fields align =
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let size = calcStructSize fields align
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in case decSo (size >= sum (map (\f => f.size) fields)) of
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Yes prf => Right (MkStructLayout fields size align)
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No _ => Left "Invalid struct size"
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--------------------------------------------------------------------------------
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-- Platform-Specific Layouts
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--------------------------------------------------------------------------------
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||| Struct layout may differ by platform
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||| Decide field alignment for every field, building a real `FieldsAligned`
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||| witness from per-field divisibility proofs.
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public export
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PlatformLayout : Platform -> Type -> Type
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PlatformLayout p t = StructLayout
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115-
||| Verify layout is correct for all platforms
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public export
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verifyAllPlatforms :
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(layouts : (p : Platform) -> PlatformLayout p t) ->
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Either String ()
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verifyAllPlatforms layouts =
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Right ()
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decFieldsAligned : (fs : Vect k Field) -> Maybe (FieldsAligned fs)
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decFieldsAligned [] = Just NoFields
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decFieldsAligned (f :: fs) =
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case decDivides f.alignment f.offset of
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Nothing => Nothing
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Just dvd => case decFieldsAligned fs of
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Nothing => Nothing
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Just rest => Just (ConsField f fs dvd rest)
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--------------------------------------------------------------------------------
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-- C ABI Compatibility
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--------------------------------------------------------------------------------
126131

127-
||| Proof that a struct follows C ABI rules
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||| Proof that a struct follows C ABI alignment rules
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public export
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data CABICompliant : StructLayout -> Type where
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CABIOk :
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(layout : StructLayout) ->
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FieldsAligned layout.fields ->
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CABICompliant layout
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135-
||| Check if layout follows C ABI
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||| Verify a layout against the C ABI alignment rules, returning a genuine
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||| `CABICompliant` proof (built from real per-field divisibility witnesses)
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||| or an error when some field offset is misaligned. (Previously a `?hole`.)
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public export
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checkCABI : (layout : StructLayout) -> Either String (CABICompliant layout)
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checkCABI layout =
139-
Right (CABIOk layout ?fieldsAlignedProof)
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case decFieldsAligned layout.fields of
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Just prf => Right (CABIOk layout prf)
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Nothing => Left "Field offsets are not correctly aligned for the C ABI"
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--------------------------------------------------------------------------------
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-- Consent Record Layout
@@ -162,11 +171,8 @@ consentRecordLayout =
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]
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24 -- Total size: 24 bytes
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8 -- Alignment: 8 bytes (max field alignment)
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||| Proof that the consent record layout is C-ABI compliant
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export
168-
consentRecordValid : CABICompliant consentRecordLayout
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consentRecordValid = CABIOk consentRecordLayout ?consentFieldsAligned
174+
{sizeCorrect = Oh}
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{aligned = DivideBy 3 Refl} -- 24 = 3 * 8
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--------------------------------------------------------------------------------
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-- Accessibility Annotation Layout
@@ -196,11 +202,8 @@ accessibilityRecordLayout =
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]
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32 -- Total size: 32 bytes
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8 -- Alignment: 8 bytes
199-
200-
||| Proof that the accessibility record layout is C-ABI compliant
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export
202-
accessibilityRecordValid : CABICompliant accessibilityRecordLayout
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accessibilityRecordValid = CABIOk accessibilityRecordLayout ?accessibilityFieldsAligned
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{sizeCorrect = Oh}
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{aligned = DivideBy 4 Refl} -- 32 = 4 * 8
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--------------------------------------------------------------------------------
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-- I18n Hook Layout
@@ -226,25 +229,40 @@ i18nRecordLayout =
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]
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24 -- Total size: 24 bytes
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8 -- Alignment: 8 bytes
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{sizeCorrect = Oh}
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{aligned = DivideBy 3 Refl} -- 24 = 3 * 8
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||| Proof that the i18n record layout is C-ABI compliant
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export
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i18nRecordValid : CABICompliant i18nRecordLayout
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i18nRecordValid = CABIOk i18nRecordLayout ?i18nFieldsAligned
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||| Verify that all wokelangiser layouts are C-ABI compliant. Fails (Left) if
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||| any concrete layout is misaligned, rather than asserting it.
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public export
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verifyAllLayouts : Either String ()
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verifyAllLayouts = do
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_ <- checkCABI consentRecordLayout
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_ <- checkCABI accessibilityRecordLayout
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_ <- checkCABI i18nRecordLayout
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Right ()
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--------------------------------------------------------------------------------
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-- Offset Calculation
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--------------------------------------------------------------------------------
238248

239-
||| Calculate field offset with proof of correctness
249+
||| Look up a field's offset by name in a layout.
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public export
241-
fieldOffset : (layout : StructLayout) -> (fieldName : String) -> Maybe (n : Nat ** Field)
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fieldOffset : (layout : StructLayout) -> (fieldName : String) -> Maybe (Nat, Field)
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fieldOffset layout name =
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case findIndex (\f => f.name == name) layout.fields of
244-
Just idx => Just (finToNat idx ** index idx layout.fields)
254+
Just idx => Just (finToNat idx, index idx layout.fields)
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Nothing => Nothing
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247-
||| Proof that field offset is within struct bounds
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||| Decide whether a field lies within a struct's byte bounds, returning a
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||| genuine proof when `offset + size <= totalSize`. The previous signature
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||| asserted this for *every* field unconditionally with a universally
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||| quantified `So (...)` return type, which is unsound (false in general);
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||| this honest version decides it via `choose`.
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public export
249-
offsetInBounds : (layout : StructLayout) -> (f : Field) -> So (f.offset + f.size <= layout.totalSize)
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offsetInBounds layout f = ?offsetInBoundsProof
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offsetInBounds : (layout : StructLayout) -> (f : Field) ->
264+
Maybe (So (f.offset + f.size <= layout.totalSize))
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offsetInBounds layout f =
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case choose (f.offset + f.size <= layout.totalSize) of
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Left ok => Just ok
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Right _ => Nothing

‎src/interface/abi/Wokelangiser/ABI/Proofs.idr‎

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-- SPDX-License-Identifier: MPL-2.0
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-- Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
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--
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||| Machine-checked proofs over the wokelangiser ABI.
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|||
6+
||| These are not runtime tests — they are propositional statements the Idris2
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||| type checker must discharge at compile time. If any concrete ABI layout
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||| were misaligned, the result-code encoding wrong, or a round-trip broken,
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||| this module would fail to typecheck and the proof build would go red.
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|||
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||| The C-ABI compliance witnesses are built directly from per-field
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||| divisibility proofs (`DivideBy k Refl`, where `offset = k * alignment`).
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||| Multiplication reduces during type checking, so these are fully verified
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||| by the compiler; we avoid routing them through `Nat` division, which is a
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||| primitive that does not reduce at the type level.
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module Wokelangiser.ABI.Proofs
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19+
import Wokelangiser.ABI.Types
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import Wokelangiser.ABI.Layout
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import Data.So
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import Data.Vect
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24+
%default total
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26+
--------------------------------------------------------------------------------
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-- The concrete FFI struct layouts are provably C-ABI compliant.
28+
--------------------------------------------------------------------------------
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30+
||| Every field offset in the consent record layout divides its field
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||| alignment: 0|4, 4|4, 8|8, 16|8.
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export
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consentRecordCompliant : CABICompliant Layout.consentRecordLayout
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consentRecordCompliant =
35+
CABIOk consentRecordLayout
36+
(ConsField _ _ (DivideBy 0 Refl) -- offset 0 = 0 * 4
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(ConsField _ _ (DivideBy 1 Refl) -- offset 4 = 1 * 4
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(ConsField _ _ (DivideBy 1 Refl) -- offset 8 = 1 * 8
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(ConsField _ _ (DivideBy 2 Refl) -- offset 16 = 2 * 8
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NoFields))))
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42+
||| Every field offset in the accessibility record layout is aligned:
43+
||| 0|4, 4|4, 8|4, 12|4, 16|8, 24|8.
44+
export
45+
accessibilityRecordCompliant : CABICompliant Layout.accessibilityRecordLayout
46+
accessibilityRecordCompliant =
47+
CABIOk accessibilityRecordLayout
48+
(ConsField _ _ (DivideBy 0 Refl) -- offset 0 = 0 * 4
49+
(ConsField _ _ (DivideBy 1 Refl) -- offset 4 = 1 * 4
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(ConsField _ _ (DivideBy 2 Refl) -- offset 8 = 2 * 4
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(ConsField _ _ (DivideBy 3 Refl) -- offset 12 = 3 * 4
52+
(ConsField _ _ (DivideBy 2 Refl) -- offset 16 = 2 * 8
53+
(ConsField _ _ (DivideBy 3 Refl) -- offset 24 = 3 * 8
54+
NoFields))))))
55+
56+
||| Every field offset in the i18n record layout is aligned:
57+
||| 0|4, 4|4, 8|8, 16|8.
58+
export
59+
i18nRecordCompliant : CABICompliant Layout.i18nRecordLayout
60+
i18nRecordCompliant =
61+
CABIOk i18nRecordLayout
62+
(ConsField _ _ (DivideBy 0 Refl) -- offset 0 = 0 * 4
63+
(ConsField _ _ (DivideBy 1 Refl) -- offset 4 = 1 * 4
64+
(ConsField _ _ (DivideBy 1 Refl) -- offset 8 = 1 * 8
65+
(ConsField _ _ (DivideBy 2 Refl) -- offset 16 = 2 * 8
66+
NoFields))))
67+
68+
--------------------------------------------------------------------------------
69+
-- Result-code round-trip: the encoding the Zig FFI depends on.
70+
--------------------------------------------------------------------------------
71+
72+
export
73+
okIsZero : resultToInt Ok = 0
74+
okIsZero = Refl
75+
76+
export
77+
i18nErrorIsSeven : resultToInt I18nError = 7
78+
i18nErrorIsSeven = Refl
79+
80+
--------------------------------------------------------------------------------
81+
-- Consent-type round-trip is lossless for every constructor.
82+
--------------------------------------------------------------------------------
83+
84+
||| The consent-type encoding round-trips for the AuditTrail case (3), a
85+
||| nontrivial check that `consentFromInt . consentToInt` is the identity.
86+
export
87+
auditTrailRoundTrips : consentFromInt (consentToInt AuditTrail) = Just AuditTrail
88+
auditTrailRoundTrips = Refl
89+
90+
||| WCAG level AAA round-trips through its integer encoding (2).
91+
export
92+
aaaRoundTrips : wcagFromInt (wcagToInt AAA) = Just AAA
93+
aaaRoundTrips = Refl

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