meson: add new version, external find support (#19658)

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

@@ -16,6 +16,9 @@ class Meson(PythonPackage):
 
     maintainers = ['michaelkuhn']
 
+    version('0.56.0', sha256='a9ca7adf66dc69fbb7e583f7c7aef16b9fe56ec2874a3d58747e69a3affdf300')
+    version('0.55.3', sha256='2b276df50c5b13ccdbfb14d3333141e9e7985aca31b60400b3f3e0be2ee6897e')
+    version('0.55.2', sha256='56244896e56c2b619f819d047b6de412ecc5250975ee8717f1e329113d178e06')
     version('0.55.1', sha256='c7ebf2fff5934a974c7edd1aebb5fc9c3e1da5ae3184a29581fde917638eea39')
     version('0.55.0', sha256='9034c943c8cf4d734c0e18e5ba038dd762fcdcc614c45b41703305da8382e90c')
     version('0.54.3', sha256='c25caff342b5368bfe33fab6108f454fcf12e2f2cef70817205872ddef669e8b')
@@ -37,4 +40,11 @@ class Meson(PythonPackage):
     # rpath modification completely to make sure that Spack's rpath changes
     # are not reverted.
     patch('rpath-0.49.patch', when='@0.49:0.53')
-    patch('rpath-0.54.patch', when='@0.54:')
+    patch('rpath-0.54.patch', when='@0.54:0.55')
+    patch('rpath-0.56.patch', when='@0.56')
+
+    executables = ['^meson$']
+
+    @classmethod
+    def determine_version(cls, exe):
+        return Executable(exe)('--version', output=str, error=str).rstrip()

var/spack/repos/builtin/packages/meson/rpath-0.56.patch

@@ -0,0 +1,20 @@
+--- a/mesonbuild/scripts/depfixer.py	2020-10-30 03:25:24.000000000 -0500
++++ b/mesonbuild/scripts/depfixer.py	2020-11-01 14:24:44.000000000 -0600
+@@ -13,6 +13,7 @@
+ # limitations under the License.
+ 
+ 
++import os
+ import sys, struct
+ import shutil, subprocess
+ import typing as T
+@@ -454,6 +455,9 @@
+ 
+ def fix_rpath(fname: str, rpath_dirs_to_remove: T.List[bytes], new_rpath: T.Union[str, bytes], final_path: str, install_name_mappings: T.Dict[str, str], verbose: bool = True) -> None:
+     global INSTALL_NAME_TOOL
++    # Do not strip rpath when run from within Spack
++    if 'SPACK_RPATH_DIRS' in os.environ:
++        return
+     # Static libraries, import libraries, debug information, headers, etc
+     # never have rpaths
+     # DLLs and EXE currently do not need runtime path fixing