Hoist trying several dependency detection methods up to find_external_dependency()

find_external_dependency() now makes and iterates over a list of callables
which are constructors with bound arguments for the dependency objects we
are going to attempt to make, so we can consolidate reporting on these
attempts and handling failures in that function.

1 files changed, 99 insertions, 102 deletions

diff --git a/mesonbuild/dependencies/ui.py b/mesonbuild/dependencies/ui.py
index 197d22c..e25d135 100644
--- a/mesonbuild/dependencies/ui.py
+++ b/mesonbuild/dependencies/ui.py
@@ -15,6 +15,7 @@
 # This file contains the detection logic for external dependencies that
 # are UI-related.
 
+import functools
 import os
 import re
 import subprocess
@@ -37,32 +38,34 @@ from .base import ConfigToolDependency
 class GLDependency(ExternalDependency):
     def __init__(self, environment, kwargs):
         super().__init__('gl', environment, None, kwargs)
-        if DependencyMethods.SYSTEM in self.methods:
-            if mesonlib.is_osx():
-                self.is_found = True
-                # FIXME: Use AppleFrameworks dependency
-                self.link_args = ['-framework', 'OpenGL']
-                # FIXME: Detect version using self.clib_compiler
-                self.version = '1'
-                return
-            if mesonlib.is_windows():
-                self.is_found = True
-                # FIXME: Use self.clib_compiler.find_library()
-                self.link_args = ['-lopengl32']
-                # FIXME: Detect version using self.clib_compiler
-                self.version = '1'
-                return
+
+        if mesonlib.is_osx():
+            self.is_found = True
+            # FIXME: Use AppleFrameworks dependency
+            self.link_args = ['-framework', 'OpenGL']
+            # FIXME: Detect version using self.clib_compiler
+            self.version = '1'
+            return
+        if mesonlib.is_windows():
+            self.is_found = True
+            # FIXME: Use self.clib_compiler.find_library()
+            self.link_args = ['-lopengl32']
+            # FIXME: Detect version using self.clib_compiler
+            self.version = '1'
+            return
 
     @classmethod
     def _factory(cls, environment, kwargs):
-        if DependencyMethods.PKGCONFIG in cls._process_method_kw(kwargs):
-            try:
-                pcdep = PkgConfigDependency('gl', environment, kwargs)
-                if pcdep.found():
-                    return pcdep
-            except Exception:
-                pass
-        return GLDependency(environment, kwargs)
+        methods = cls._process_method_kw(kwargs)
+        candidates = []
+
+        if DependencyMethods.PKGCONFIG in methods:
+            candidates.append(functools.partial(PkgConfigDependency, 'gl', environment, kwargs))
+
+        if DependencyMethods.SYSTEM in methods:
+            candidates.append(functools.partial(GLDependency), environment, kwargs)
+
+        return candidates
 
     @staticmethod
     def get_methods():
@@ -452,33 +455,27 @@ class SDL2Dependency(ExternalDependency):
     @classmethod
     def _factory(cls, environment, kwargs):
         methods = cls._process_method_kw(kwargs)
+        candidates = []
+
         if DependencyMethods.PKGCONFIG in methods:
-            try:
-                pcdep = PkgConfigDependency('sdl2', environment, kwargs)
-                if pcdep.found():
-                    return pcdep
-            except Exception as e:
-                mlog.debug('SDL 2 not found via pkgconfig. Trying next, error was:', str(e))
+            candidates.append(functools.partial(PkgConfigDependency, 'sdl2', environment, kwargs))
+
         if DependencyMethods.CONFIG_TOOL in methods:
-            try:
-                ctdep = ConfigToolDependency.factory(
-                    'sdl2', environment, None, kwargs, ['sdl2-config'], 'sdl2-config')
-                if ctdep.found():
-                    ctdep.compile_args = ctdep.get_config_value(['--cflags'], 'compile_args')
-                    ctdep.link_args = ctdep.get_config_value(['--libs'], 'link_args')
-                    return ctdep
-            except Exception as e:
-                mlog.debug('SDL 2 not found via sdl2-config. Trying next, error was:', str(e))
+            candidates.append(functools.partial(ConfigToolDependency.factory,
+                                                'sdl2', environment, None,
+                                                kwargs, ['sdl2-config'],
+                                                'sdl2-config'))
+#                if ctdep.found():
+#                    ctdep.compile_args = ctdep.get_config_value(['--cflags'], 'compile_args')
+#                    ctdep.link_args = ctdep.get_config_value(['--libs'], 'link_args')
+
         if DependencyMethods.EXTRAFRAMEWORK in methods:
             if mesonlib.is_osx():
-                fwdep = ExtraFrameworkDependency('sdl2', False, None, environment,
-                                                 kwargs.get('language', None), kwargs)
-                if fwdep.found():
-                    fwdep.version = '2'  # FIXME
-                    return fwdep
-            mlog.log('Dependency', mlog.bold('sdl2'), 'found:', mlog.red('NO'))
-
-        return SDL2Dependency(environment, kwargs)
+                candidates.append(functools.partial(ExtraFrameworkDependency,
+                                                    'sdl2', False, None, environment,
+                                                    kwargs.get('language', None), kwargs))
+                # fwdep.version = '2'  # FIXME
+        return candidates
 
     @staticmethod
     def get_methods():
@@ -518,73 +515,73 @@ class VulkanDependency(ExternalDependency):
     def __init__(self, environment, kwargs):
         super().__init__('vulkan', environment, None, kwargs)
 
-        if DependencyMethods.SYSTEM in self.methods:
-            try:
-                self.vulkan_sdk = os.environ['VULKAN_SDK']
-                if not os.path.isabs(self.vulkan_sdk):
-                    raise DependencyException('VULKAN_SDK must be an absolute path.')
-            except KeyError:
-                self.vulkan_sdk = None
-
-            if self.vulkan_sdk:
-                # TODO: this config might not work on some platforms, fix bugs as reported
-                # we should at least detect other 64-bit platforms (e.g. armv8)
+        try:
+            self.vulkan_sdk = os.environ['VULKAN_SDK']
+            if not os.path.isabs(self.vulkan_sdk):
+                raise DependencyException('VULKAN_SDK must be an absolute path.')
+        except KeyError:
+            self.vulkan_sdk = None
+
+        if self.vulkan_sdk:
+            # TODO: this config might not work on some platforms, fix bugs as reported
+            # we should at least detect other 64-bit platforms (e.g. armv8)
+            lib_name = 'vulkan'
+            if mesonlib.is_windows():
+                lib_name = 'vulkan-1'
+                lib_dir = 'Lib32'
+                inc_dir = 'Include'
+                if detect_cpu({}) == 'x86_64':
+                    lib_dir = 'Lib'
+            else:
                 lib_name = 'vulkan'
-                if mesonlib.is_windows():
-                    lib_name = 'vulkan-1'
-                    lib_dir = 'Lib32'
-                    inc_dir = 'Include'
-                    if detect_cpu({}) == 'x86_64':
-                        lib_dir = 'Lib'
-                else:
-                    lib_name = 'vulkan'
-                    lib_dir = 'lib'
-                    inc_dir = 'include'
+                lib_dir = 'lib'
+                inc_dir = 'include'
 
-                # make sure header and lib are valid
-                inc_path = os.path.join(self.vulkan_sdk, inc_dir)
-                header = os.path.join(inc_path, 'vulkan', 'vulkan.h')
-                lib_path = os.path.join(self.vulkan_sdk, lib_dir)
-                find_lib = self.clib_compiler.find_library(lib_name, environment, lib_path)
+            # make sure header and lib are valid
+            inc_path = os.path.join(self.vulkan_sdk, inc_dir)
+            header = os.path.join(inc_path, 'vulkan', 'vulkan.h')
+            lib_path = os.path.join(self.vulkan_sdk, lib_dir)
+            find_lib = self.clib_compiler.find_library(lib_name, environment, lib_path)
 
-                if not find_lib:
-                    raise DependencyException('VULKAN_SDK point to invalid directory (no lib)')
+            if not find_lib:
+                raise DependencyException('VULKAN_SDK point to invalid directory (no lib)')
 
-                if not os.path.isfile(header):
-                    raise DependencyException('VULKAN_SDK point to invalid directory (no include)')
+            if not os.path.isfile(header):
+                raise DependencyException('VULKAN_SDK point to invalid directory (no include)')
 
-                self.type_name = 'vulkan_sdk'
-                self.is_found = True
-                self.compile_args.append('-I' + inc_path)
-                self.link_args.append('-L' + lib_path)
-                self.link_args.append('-l' + lib_name)
+            self.type_name = 'vulkan_sdk'
+            self.is_found = True
+            self.compile_args.append('-I' + inc_path)
+            self.link_args.append('-L' + lib_path)
+            self.link_args.append('-l' + lib_name)
 
-                # TODO: find a way to retrieve the version from the sdk?
-                # Usually it is a part of the path to it (but does not have to be)
-                self.version = '1'
+            # TODO: find a way to retrieve the version from the sdk?
+            # Usually it is a part of the path to it (but does not have to be)
+            self.version = '1'
+            return
+        else:
+            # simply try to guess it, usually works on linux
+            libs = self.clib_compiler.find_library('vulkan', environment, [])
+            if libs is not None and self.clib_compiler.has_header('vulkan/vulkan.h', '', environment):
+                self.type_name = 'system'
+                self.is_found = True
+                self.version = 1 # TODO
+                for lib in libs:
+                    self.link_args.append(lib)
                 return
-            else:
-                # simply try to guess it, usually works on linux
-                libs = self.clib_compiler.find_library('vulkan', environment, [])
-                if libs is not None and self.clib_compiler.has_header('vulkan/vulkan.h', '', environment):
-                    self.type_name = 'system'
-                    self.is_found = True
-                    self.version = 1 # TODO
-                    for lib in libs:
-                        self.link_args.append(lib)
-                    return
 
     @classmethod
     def _factory(cls, environment, kwargs):
-        if DependencyMethods.PKGCONFIG in cls._process_method_kw(kwargs):
-            try:
-                pcdep = PkgConfigDependency('vulkan', environment, kwargs)
-                if pcdep.found():
-                    return pcdep
-            except Exception:
-                pass
+        methods = cls._process_method_kw(kwargs)
+        candidates = []
 
-        return VulkanDependency(environment, kwargs)
+        if DependencyMethods.PKGCONFIG in methods:
+            candidates.append(functools.partial(PkgConfigDependency, 'vulkan', environment, kwargs))
+
+        if DependencyMethods.PKGCONFIG in methods:
+            candidates.append(functools.partial(VulkanDependency, environment, kwargs))
+
+        return candidates
 
     @staticmethod
     def get_methods():