From 4576fbe6486c4fdc5162a5929e97803d0bc572f8 Mon Sep 17 00:00:00 2001
From: Brian Van Essen <vanessen1@llnl.gov>
Date: Tue, 3 May 2022 00:04:50 -0700
Subject: OpenCV and OpenBLAS: add external find support (#30240)

Added support for finding the OpenCV package via the find external
command. Included support for identifying variants based on available
shared libraries.

Added support to finding the OpenBLAS package via the find external
command.

Enabled packages to show that they can be discovered via the find
external command in the info message.

Updated the OpenCV and OpenBLAS packages to use the extensible search
mechanism for library extensions on multiple OS platforms.

Corrected how find externals works on Darwin for OpenCV and OpenBLAS
to accommodate that the version numbers are placed before the file
extension instead of after it, as on Linux.

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>
Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>
---
 .../repos/builtin/packages/openblas/package.py     | 14 ++++++
 var/spack/repos/builtin/packages/opencv/package.py | 52 ++++++++++++++++++++++
 2 files changed, 66 insertions(+)

(limited to 'var')

diff --git a/var/spack/repos/builtin/packages/openblas/package.py b/var/spack/repos/builtin/packages/openblas/package.py
index bc85dcb000..e44f8ffaa3 100644
--- a/var/spack/repos/builtin/packages/openblas/package.py
+++ b/var/spack/repos/builtin/packages/openblas/package.py
@@ -6,6 +6,8 @@
 import os
 import re
 
+from llnl.util.filesystem import library_extensions
+
 from spack import *
 from spack.package_test import compare_output_file, compile_c_and_execute
 
@@ -17,6 +19,8 @@ class Openblas(MakefilePackage):
     url      = 'https://github.com/xianyi/OpenBLAS/archive/v0.2.19.tar.gz'
     git      = 'https://github.com/xianyi/OpenBLAS.git'
 
+    libraries = ['libopenblas']
+
     version('develop', branch='develop')
     version('0.3.20', sha256='8495c9affc536253648e942908e88e097f2ec7753ede55aca52e5dead3029e3c')
     version('0.3.19', sha256='947f51bfe50c2a0749304fbe373e00e7637600b0a47b78a51382aeb30ca08562')
@@ -145,6 +149,16 @@ class Openblas(MakefilePackage):
 
     depends_on('perl', type='build')
 
+    @classmethod
+    def determine_version(cls, lib):
+        ver = None
+        for ext in library_extensions:
+            match = re.search(r'lib(\S*?)-r(\d+\.\d+\.\d+)\.%s' %
+                              ext, lib)
+            if match:
+                ver = match.group(2)
+        return ver
+
     @property
     def parallel(self):
         # unclear whether setting `-j N` externally was supported before 0.3
diff --git a/var/spack/repos/builtin/packages/opencv/package.py b/var/spack/repos/builtin/packages/opencv/package.py
index 9ae1492c71..bf96ed08d4 100644
--- a/var/spack/repos/builtin/packages/opencv/package.py
+++ b/var/spack/repos/builtin/packages/opencv/package.py
@@ -3,6 +3,10 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+import re
+
+from llnl.util.filesystem import library_extensions
+
 
 class Opencv(CMakePackage, CudaPackage):
     """OpenCV (Open Source Computer Vision Library) is an open source computer
@@ -233,10 +237,16 @@ class Opencv(CMakePackage, CudaPackage):
         "js_bindings_generator",
     ]
 
+    # Define the list of libraries objects that may be used
+    # to find an external installation and its variants
+    libraries = []
+
     # module variants
     for mod in modules:
         # At least one of these modules must be enabled to build OpenCV
         variant(mod, default=False, description="Include opencv_{0} module".format(mod))
+        lib = 'libopencv_' + mod
+        libraries.append(lib)
 
     # module conflicts and dependencies
     with when("+calib3d"):
@@ -873,6 +883,48 @@ class Opencv(CMakePackage, CudaPackage):
     conflicts("+win32ui", when="platform=linux", msg="Windows only")
     conflicts("+win32ui", when="platform=cray", msg="Windows only")
 
+    @classmethod
+    def determine_version(cls, lib):
+        ver = None
+        for ext in library_extensions:
+            pattern = None
+            if ext == 'dylib':
+                # Darwin switches the order of the version compared to Linux
+                pattern = re.compile(r'lib(\S*?)_(\S*)\.(\d+\.\d+\.\d+)\.%s' %
+                                     ext)
+            else:
+                pattern = re.compile(r'lib(\S*?)_(\S*)\.%s\.(\d+\.\d+\.\d+)' %
+                                     ext)
+            match = pattern.search(lib)
+            if match:
+                ver = match.group(3)
+        return ver
+
+    @classmethod
+    def determine_variants(cls, libs, version_str):
+        variants = []
+        remaining_modules = set(Opencv.modules)
+        for lib in libs:
+            for ext in library_extensions:
+                pattern = None
+                if ext == 'dylib':
+                    # Darwin switches the order of the version compared to Linux
+                    pattern = re.compile(r'lib(\S*?)_(\S*)\.(\d+\.\d+\.\d+)\.%s' %
+                                         ext)
+                else:
+                    pattern = re.compile(r'lib(\S*?)_(\S*)\.%s\.(\d+\.\d+\.\d+)' %
+                                         ext)
+                match = pattern.search(lib)
+                if match and not match.group(2) == 'core':
+                    variants.append('+' + match.group(2))
+                    remaining_modules.remove(match.group(2))
+
+        # If libraries are not found, mark those variants as disabled
+        for mod in remaining_modules:
+            variants.append('~' + mod)
+
+        return ' '.join(variants)
+
     def cmake_args(self):
         spec = self.spec
         args = [
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