Adding externals for bison and flex (#18358)

* Adding externals for bison and flex

Added because bison actually pulls in a ton of stuff.

* Need to escape parentheses.

* Need to add re package.

* Adding re package.

var/spack/repos/builtin/packages/bison/package.py

@@ -6,6 +6,7 @@
 from spack import *
 from spack.operating_systems.mac_os import macos_version
 import sys
+import re
 
 
 class Bison(AutotoolsPackage, GNUMirrorPackage):
@@ -16,6 +17,8 @@ class Bison(AutotoolsPackage, GNUMirrorPackage):
     homepage = "https://www.gnu.org/software/bison/"
     gnu_mirror_path = "bison/bison-3.6.4.tar.gz"
 
+    executables = ['^bison$']
+
     version('3.6.4', sha256='8183de64b5383f3634942c7b151bf2577f74273b2731574cdda8a8f3a0ab13e9')
     version('3.6.3', sha256='4b4c4943931e811f1073006ce3d8ee022a02b11b501e9cbf4def3613b24a3e63')
     version('3.6.2', sha256='e28ed3aad934de2d1df68be209ac0b454f7b6d3c3d6d01126e5cd2cbadba089a')
@@ -49,3 +52,9 @@ class Bison(AutotoolsPackage, GNUMirrorPackage):
         patch('secure_snprintf.patch', level=0, when='@3.0.4')
 
     build_directory = 'spack-build'
+
+    @classmethod
+    def determine_version(cls, exe):
+        output = Executable(exe)('--version', output=str, error=str)
+        match = re.search(r'bison \(GNU Bison\)\s+(\S+)', output)
+        return match.group(1) if match else None

var/spack/repos/builtin/packages/flex/package.py

@@ -5,6 +5,7 @@
 
 from spack import *
 import os
+import re
 
 
 class Flex(AutotoolsPackage):
@@ -13,6 +14,8 @@ class Flex(AutotoolsPackage):
     homepage = "https://github.com/westes/flex"
     url = "https://github.com/westes/flex/releases/download/v2.6.1/flex-2.6.1.tar.gz"
 
+    executables = ['^flex$']
+
     version('2.6.4', sha256='e87aae032bf07c26f85ac0ed3250998c37621d95f8bd748b31f15b33c45ee995')
     version('2.6.3', sha256='68b2742233e747c462f781462a2a1e299dc6207401dac8f0bbb316f48565c2aa')
     # Avoid flex '2.6.2' (major bug)
@@ -43,6 +46,25 @@ class Flex(AutotoolsPackage):
     # - https://github.com/westes/flex/issues/241
     patch('https://github.com/westes/flex/commit/24fd0551333e7eded87b64dd36062da3df2f6380.patch', sha256='09c22e5c6fef327d3e48eb23f0d610dcd3a35ab9207f12e0f875701c677978d3', when='@2.6.4')
 
+    @classmethod
+    def determine_version(cls, exe):
+        output = Executable(exe)('--version', output=str, error=str)
+        match = re.search(r'flex\s+(\S+)', output)
+        return match.group(1) if match else None
+
+    @classmethod
+    def determine_variants(cls, exes, version):
+        results = []
+        for exe in exes:
+            variants = ''
+            path = os.path.dirname(exe)
+            if 'lex' in os.listdir(path):
+                variants += "+lex"
+            else:
+                variants += "~lex"
+            results.append(variants)
+        return results
+
     @when('@:2.6.0,2.6.4')
     def autoreconf(self, spec, prefix):
         autogen = Executable('./autogen.sh')