Add alex to build-tool-depends remove separate code gen (#8980)

* Add alex to build-tool-depends and remove separate code gen

- Pass latin-1 encoding is passed as input pragma
- Cabal hard-codes -g for alex so we don't need to worry about --ghc
- Rework bootstrap, adding per-component building
- Update bootstrap plans

* [bootstrap] warn the user if cabal config is not found

* [bootstrap] regenerate bootstrap plans once more

* [bootstrap] regenerate bootstrap files after #9139

Cabal-syntax/Cabal-syntax.cabal

@@ -58,6 +58,8 @@ library
   if impl(ghc >= 8.0) && impl(ghc < 8.8)
     ghc-options: -Wnoncanonical-monadfail-instances
 
+  build-tool-depends: alex:alex
+
   exposed-modules:
     Distribution.Backpack
     Distribution.CabalSpecVersion

templates/Lexer.x → Cabal-syntax/src/Distribution/Fields/Lexer.x

@@ -19,18 +19,6 @@ module Distribution.Fields.Lexer
   ,bol_section, in_section, in_field_layout, in_field_braces
   ,mkLexState) where
 
--- [Note: bootstrapping parsec parser]
---
--- We manually produce the `Lexer.hs` file from `boot/Lexer.x` (make lexer)
--- because bootstrapping cabal-install would be otherwise tricky.
--- Alex is (atm) tricky package to build, cabal-install has some magic
--- to move bundled generated files in place, so rather we don't depend
--- on it before we can build it ourselves.
--- Therefore there is one thing less to worry in bootstrap.sh, which is a win.
---
--- See also https://github.com/haskell/cabal/issues/4633
---
-
 import Prelude ()
 import qualified Prelude as Prelude
 import Distribution.Compat.Prelude
@@ -53,6 +41,8 @@ import qualified Data.Text.Encoding.Error as T
 }
 -- Various character classes
 
+%encoding "latin1"
+
 $space           = \          -- single space char
 $ctlchar         = [\x0-\x1f \x7f]
 $printable       = \x0-\xff # $ctlchar   -- so no \n \r

Makefile

@@ -25,19 +25,6 @@ style-modified: ## Run the code styler on modified files
 	@git ls-files --modified Cabal Cabal-syntax cabal-install \
 		| grep '.hs$$' | xargs -P $(PROCS) -I {} fourmolu -q -i {}
 
-# source generation: Lexer
-
-LEXER_HS:=Cabal-syntax/src/Distribution/Fields/Lexer.hs
-
-lexer : $(LEXER_HS)
-
-$(LEXER_HS) : templates/Lexer.x
-	alex --latin1 --ghc -o $@ $^
-	@rm -f Lexer.tmp
-	echo '{- FOURMOLU_DISABLE -}' >> Lexer.tmp
-	cat -s $@ >> Lexer.tmp
-	mv Lexer.tmp $@
-
 # source generation: SPDX
 
 SPDX_LICENSE_HS:=Cabal-syntax/src/Distribution/SPDX/LicenseId.hs

bootstrap/bootstrap.py

@@ -64,6 +64,7 @@ class PackageSource(Enum):
     ('revision', Optional[int]),
     ('cabal_sha256', Optional[SHA256Hash]),
     ('flags', List[str]),
+    ('component', Optional[str])
 ])
 
 BootstrapInfo = NamedTuple('BootstrapInfo', [
@@ -189,9 +190,9 @@ def install_dep(dep: BootstrapDep, ghc: Compiler) -> None:
 
     sdist_dir = resolve_dep(dep)
 
-    install_sdist(dist_dir, sdist_dir, ghc, dep.flags)
+    install_sdist(dist_dir, sdist_dir, ghc, dep.flags, dep.component)
 
-def install_sdist(dist_dir: Path, sdist_dir: Path, ghc: Compiler, flags: List[str]):
+def install_sdist(dist_dir: Path, sdist_dir: Path, ghc: Compiler, flags: List[str], component):
     prefix = PSEUDOSTORE.resolve()
     flags_option = ' '.join(flags)
     setup_dist_dir = dist_dir / 'setup'
@@ -205,10 +206,12 @@ def install_sdist(dist_dir: Path, sdist_dir: Path, ghc: Compiler, flags: List[st
         f'--package-db={PKG_DB.resolve()}',
         f'--prefix={prefix}',
         f'--bindir={BINDIR.resolve()}',
+        f'--extra-prog-path={BINDIR.resolve()}',
         f'--with-compiler={ghc.ghc_path}',
         f'--with-hc-pkg={ghc.ghc_pkg_path}',
         f'--with-hsc2hs={ghc.hsc2hs_path}',
         f'--flags={flags_option}',
+        f'{component or ""}'
     ]
 
     def check_call(args: List[str]) -> None:

bootstrap/cabal.project

@@ -3,6 +3,3 @@
 
 packages: .
 optimization: False
-
-allow-newer:
-  cabal-install-parsers:Cabal-syntax