fix(nix): split inter-hub-models into two Cabal library components
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GHC 9.10.3 crashes with Data.Binary.Get.runGet at position 287686318
invariantly when compiling all 476 inter-hub-models modules in a single
--make invocation. Split into two library components to force two
separate GHC compilations:

  models-inner (~63 modules): Generated.ActualTypes.* + Generated.Enums
    Pure type definitions; zero inter-hub-models dependencies.
  main library (~413 modules): entity ops + Include instances
    Depends on models-inner.

Longer-term this is the right architecture: explicit boundaries reduce
build cost, isolate changes, and make diagnostics cheaper.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-05-01 21:51:47 +02:00
parent 76347ae1b5
commit 5378eb881e

174
flake.nix
View File

@@ -110,42 +110,156 @@
let drv = hprev.mkDerivation args;
in if (args.pname or "") == "inter-hub-models"
then drv.overrideAttrs (old: {
# Root cause: "module M" re-export syntax in IHP-generated hubs
# causes GHC to embed the FULL interface of M into the hub's .hi.
# Generated.ActualTypes uses "module M" for 61 sub-modules; the
# resulting ActualTypes.hi hits the GHC 9.10.3 Data.Binary.Get
# 274 MB limit (crashes at position 287686318: not enough bytes)
# when WidgetVersionInclude reads it back. Same pattern applied to
# Generated.Types (119 entity re-exports) — made into empty stub
# with direct imports in inter-hub-lib instead.
# Fix for ActualTypes: remove the explicit (module M, ...) export
# list so GHC stores compact name-reference entries in the .hi.
# GHC 9.10.3 crash: Data.Binary.Get.runGet at position 287686318.
# Invariant regardless of flags. Workaround: split the 476-module
# inter-hub-models into two Cabal library components so GHC runs
# two separate --make invocations instead of one giant one.
#
# models-inner (~63 modules): Generated.ActualTypes.* + Enums.
# Pure type definitions; no inter-hub-models deps.
# main library (~413 modules): entity ops + Include instances.
# Depends on models-inner.
#
# Long-term intent: explicit module boundaries reduce build cost,
# isolate changes, and make diagnostics cheaper across the board.
configureFlags = (old.configureFlags or []) ++ [
"--ghc-option=-O0"
"--ghc-option=-fomit-interface-pragmas"
];
postUnpack = (old.postUnpack or "") + ''
# Strip "module M" re-export syntax from Generated.ActualTypes.
# With 61 "module M" entries GHC embeds every sub-interface
# into ActualTypes.hi, producing a file that hits the GHC 9.10.3
# Data.Binary.Get 274 MB limit (crashes at position 287686318)
# when WidgetVersionInclude reads it. Removing the explicit
# export list keeps the module semantically identical (all
# imports are still re-exported) but forces GHC to use
# compact name-reference entries instead of embedded copies.
_actual="$sourceRoot/build/Generated/ActualTypes.hs"
awk '/^module Generated\.ActualTypes /{print "module Generated.ActualTypes where"; next} {print}' \
"$_actual" > "$_actual.new" && mv "$_actual.new" "$_actual"
_types="$sourceRoot/build/Generated/Types.hs"
printf '%s\n' 'module Generated.Types () where' > "$_types"
# Remove Generated.Types from exposed-modules:
# reduces HPT entry count by 1 (476 instead of 477).
_cabal=$(ls "$sourceRoot"/*.cabal | head -1)
awk '/Generated\.Types$/ && !/TypesPart/{next} {print}' \
"$_cabal" > "$_cabal.new"
mv "$_cabal.new" "$_cabal"
_pname=$(grep '^name:' "$_cabal" | awk '{print $2}')
# Classify exposed-modules into inner vs outer.
# Inner: Generated.ActualTypes.X (capital X) and Generated.Enums
# these have zero inter-hub-models dependencies.
# Outer: everything else except Generated.Types (empty stub).
_inner=$(awk '
/^ exposed-modules:/{e=1;next}
e && /^ /{m=$1;
if (m~/^Generated\.ActualTypes\.[A-Z]/||m=="Generated.Enums")
print m;
next}
e{e=0}
' "$_cabal")
_outer=$(awk '
/^ exposed-modules:/{e=1;next}
e && /^ /{m=$1;
if (!(m~/^Generated\.ActualTypes\.[A-Z]/) &&
m!="Generated.Enums" && m!="Generated.Types")
print m;
next}
e{e=0}
' "$_cabal")
# Rewrite the cabal file with two library stanzas.
# Hard-coded deps/extensions match IHP default.nix template
# (pinned flake these won't drift without a flake update).
cat > "$_cabal" <<CABAL_EOF
cabal-version: 2.2
name: $_pname
version: 0.1.0
build-type: Simple
library models-inner
default-language: GHC2021
hs-source-dirs: build
build-depends:
base
, ihp
, basic-prelude
, text
, bytestring
, time
, uuid
, aeson
, postgresql-simple
, deepseq
, data-default
, scientific
, string-conversions
, hasql
, hasql-dynamic-statements
, hasql-implicits
, hasql-mapping
, hasql-postgresql-types
, hasql-pool
, unordered-containers
, postgresql-types
exposed-modules:
$(echo "$_inner" | sed 's/^/ /')
default-extensions:
OverloadedStrings
NoImplicitPrelude
ImplicitParams
TypeSynonymInstances
FlexibleInstances
FlexibleContexts
InstanceSigs
MultiParamTypeClasses
TypeFamilies
DataKinds
TypeOperators
UndecidableInstances
ConstraintKinds
StandaloneDeriving
DuplicateRecordFields
OverloadedLabels
OverloadedRecordDot
ghc-options: -Wno-unused-imports -Wno-dodgy-imports -Wno-unused-matches
library
default-language: GHC2021
hs-source-dirs: build
build-depends:
$_pname:models-inner
, base
, ihp
, basic-prelude
, text
, bytestring
, time
, uuid
, aeson
, postgresql-simple
, deepseq
, data-default
, scientific
, string-conversions
, hasql
, hasql-dynamic-statements
, hasql-implicits
, hasql-mapping
, hasql-postgresql-types
, hasql-pool
, unordered-containers
, postgresql-types
exposed-modules:
$(echo "$_outer" | sed 's/^/ /')
default-extensions:
OverloadedStrings
NoImplicitPrelude
ImplicitParams
TypeSynonymInstances
FlexibleInstances
FlexibleContexts
InstanceSigs
MultiParamTypeClasses
TypeFamilies
DataKinds
TypeOperators
UndecidableInstances
ConstraintKinds
StandaloneDeriving
DuplicateRecordFields
OverloadedLabels
OverloadedRecordDot
ghc-options: -Wno-unused-imports -Wno-dodgy-imports -Wno-unused-matches
CABAL_EOF
# Stub out Generated.Types (kept as file for inter-hub-lib)
printf '%s\n' 'module Generated.Types () where' \
> "$sourceRoot/build/Generated/Types.hs"
'';
})
else if (args.pname or "") == "inter-hub-lib"