Add shaderc dependency lookup logic

docs/markdown/Dependencies.md

@@ -483,6 +483,18 @@ Meson substitutes `modules` to `wx-config` invocation, it generates
 - `compile_args` using `wx-config --cxxflags $modules...`
 - `link_args` using `wx-config --libs $modules...`
 
+## Shaderc
+
+*(added 0.51.0)*
+
+Shaderc currently does not ship with any means of detection. Nevertheless, Meson
+can try to detect it using `pkg-config`, but will default to looking for the
+appropriate library manually. If the `static` keyword argument is `true`,
+`shaderc_combined` is preferred. Otherwise, `shaderc_shared` is preferred. Note
+that it is not possible to obtain the shaderc version using this method.
+
+`method` may be `auto`, `pkg-config` or `system`.
+
 ### Example
 
 ```meson

mesonbuild/dependencies/__init__.py

@@ -18,7 +18,7 @@ from .base import (  # noqa: F401
     ExternalDependency, NotFoundDependency, ExternalLibrary, ExtraFrameworkDependency, InternalDependency,
     PkgConfigDependency, CMakeDependency, find_external_dependency, get_dep_identifier, packages, _packages_accept_language)
 from .dev import GMockDependency, GTestDependency, LLVMDependency, ValgrindDependency
-from .misc import (CoarrayDependency, HDF5Dependency, MPIDependency, NetCDFDependency, OpenMPDependency, Python3Dependency, ThreadDependency, PcapDependency, CupsDependency, LibWmfDependency, LibGCryptDependency)
+from .misc import (CoarrayDependency, HDF5Dependency, MPIDependency, NetCDFDependency, OpenMPDependency, Python3Dependency, ThreadDependency, PcapDependency, CupsDependency, LibWmfDependency, LibGCryptDependency, ShadercDependency)
 from .platform import AppleFrameworks
 from .ui import GLDependency, GnuStepDependency, Qt4Dependency, Qt5Dependency, SDL2Dependency, WxDependency, VulkanDependency
 
@@ -43,6 +43,7 @@ packages.update({
     'cups': CupsDependency,
     'libwmf': LibWmfDependency,
     'libgcrypt': LibGCryptDependency,
+    'shaderc': ShadercDependency,
 
     # From platform:
     'appleframeworks': AppleFrameworks,

mesonbuild/dependencies/misc.py

@@ -117,6 +117,7 @@ class HDF5Dependency(ExternalDependency):
             except Exception:
                 pass
 
+
 class NetCDFDependency(ExternalDependency):
 
     def __init__(self, environment, kwargs):
@@ -666,3 +667,49 @@ class LibGCryptDependency(ExternalDependency):
     @staticmethod
     def get_methods():
         return [DependencyMethods.PKGCONFIG, DependencyMethods.CONFIG_TOOL]
+
+
+class ShadercDependency(ExternalDependency):
+
+    def __init__(self, environment, kwargs):
+        super().__init__('shaderc', environment, None, kwargs)
+
+        static_lib = 'shaderc_combined'
+        shared_lib = 'shaderc_shared'
+
+        libs = [shared_lib, static_lib]
+        if self.static:
+            libs.reverse()
+
+        cc = self.get_compiler()
+
+        for lib in libs:
+            self.link_args = cc.find_library(lib, environment, [])
+            if self.link_args is not None:
+                self.is_found = True
+
+                if self.static and lib != static_lib:
+                    mlog.warning('Static library {!r} not found for dependency {!r}, may '
+                                 'not be statically linked'.format(static_lib, self.name))
+
+                break
+
+    def log_tried(self):
+        return 'system'
+
+    @classmethod
+    def _factory(cls, environment, kwargs):
+        methods = cls._process_method_kw(kwargs)
+        candidates = []
+
+        if DependencyMethods.SYSTEM in methods:
+            candidates.append(functools.partial(ShadercDependency, environment, kwargs))
+
+        if DependencyMethods.PKGCONFIG in methods:
+            candidates.append(functools.partial(PkgConfigDependency, 'shaderc', environment, kwargs))
+
+        return candidates
+
+    @staticmethod
+    def get_methods():
+        return [DependencyMethods.SYSTEM, DependencyMethods.PKGCONFIG]