dependencies/misc: don't special case threads

Instad of having special casing of threads in the backends and
everywehre else, do what we did for openmp, create a real
dependency. Then make use of the fact that dependencies can now have
sub dependencies to add threads.

7 files changed, 9 insertions, 29 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index d752ac4..124d40f 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -643,8 +643,6 @@ class Backend:
                 commands += dep.get_exe_args(compiler)
             # For 'automagic' deps: Boost and GTest. Also dependency('threads').
             # pkg-config puts the thread flags itself via `Cflags:`
-            if dep.need_threads():
-                commands += compiler.thread_flags(self.environment)
         # Fortran requires extra include directives.
         if compiler.language == 'fortran':
             for lt in target.link_targets:
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 64ea5a6..a3b9ce8 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -2511,7 +2511,6 @@ rule FORTRAN_DEP_HACK%s
         if not isinstance(target, build.StaticLibrary):
             # For 'automagic' deps: Boost and GTest. Also dependency('threads').
             # pkg-config puts the thread flags itself via `Cflags:`
-            need_threads = False
 
             commands += target.link_args
             # External deps must be last because target link libraries may depend on them.
@@ -2519,14 +2518,10 @@ rule FORTRAN_DEP_HACK%s
                 # Extend without reordering or de-dup to preserve `-L -l` sets
                 # https://github.com/mesonbuild/meson/issues/1718
                 commands.extend_preserving_lflags(dep.get_link_args())
-                need_threads |= dep.need_threads()
             for d in target.get_dependencies():
                 if isinstance(d, build.StaticLibrary):
                     for dep in d.get_external_deps():
-                        need_threads |= dep.need_threads()
                         commands.extend_preserving_lflags(dep.get_link_args())
-            if need_threads:
-                commands += linker.thread_link_flags(self.environment)
 
         # Add link args specific to this BuildTarget type that must not be overridden by dependencies
         commands += self.get_target_type_link_args_post_dependencies(target, linker)
diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index bcf8243..0a6e3b3 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -433,13 +433,9 @@ class CCompiler(Compiler):
         for d in dependencies:
             # Add compile flags needed by dependencies
             args += d.get_compile_args()
-            if d.need_threads():
-                args += self.thread_flags(env)
             if mode == 'link':
                 # Add link flags needed to find dependencies
                 args += d.get_link_args()
-                if d.need_threads():
-                    args += self.thread_link_flags(env)
 
         args += self._get_basic_compiler_args(env, mode)
 
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 032fe60..aae2572 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -153,9 +153,6 @@ class Dependency:
     def get_exe_args(self, compiler):
         return []
 
-    def need_threads(self):
-        return False
-
     def get_pkgconfig_variable(self, variable_name, kwargs):
         raise DependencyException('{!r} is not a pkgconfig dependency'.format(self.name))
 
diff --git a/mesonbuild/dependencies/boost.py b/mesonbuild/dependencies/boost.py
index 6a8050d..62a652a 100644
--- a/mesonbuild/dependencies/boost.py
+++ b/mesonbuild/dependencies/boost.py
@@ -22,6 +22,7 @@ from .. import mesonlib
 from ..environment import detect_cpu_family
 
 from .base import (DependencyException, ExternalDependency)
+from .misc import ThreadDependency
 
 # On windows 3 directory layouts are supported:
 # * The default layout (versioned) installed:
@@ -103,6 +104,8 @@ class BoostDependency(ExternalDependency):
         self.is_multithreading = threading == "multi"
 
         self.requested_modules = self.get_requested(kwargs)
+        if 'thread' in self.requested_modules:
+            self.ext_deps.append(ThreadDependency(environment, kwargs))
 
         self.boost_root = None
         self.boost_roots = []
@@ -488,9 +491,6 @@ class BoostDependency(ExternalDependency):
     def get_sources(self):
         return []
 
-    def need_threads(self):
-        return 'thread' in self.requested_modules
-
 
 # Generated with boost_names.py
 BOOST_LIBS = [
diff --git a/mesonbuild/dependencies/dev.py b/mesonbuild/dependencies/dev.py
index 57a6a96..fb7b017 100644
--- a/mesonbuild/dependencies/dev.py
+++ b/mesonbuild/dependencies/dev.py
@@ -26,6 +26,7 @@ from .base import (
     DependencyException, DependencyMethods, ExternalDependency, PkgConfigDependency,
     strip_system_libdirs, ConfigToolDependency,
 )
+from .misc import ThreadDependency
 
 
 def get_shared_library_suffix(environment, native):
@@ -45,6 +46,7 @@ class GTestDependency(ExternalDependency):
         self.main = kwargs.get('main', False)
         self.src_dirs = ['/usr/src/gtest/src', '/usr/src/googletest/googletest/src']
         self.detect()
+        self.ext_deps.append(ThreadDependency(environment, kwargs))
 
     def detect(self):
         gtest_detect = self.clib_compiler.find_library("gtest", self.env, [])
@@ -83,9 +85,6 @@ class GTestDependency(ExternalDependency):
                 return True
         return False
 
-    def need_threads(self):
-        return True
-
     def log_info(self):
         if self.prebuilt:
             return 'prebuilt'
@@ -118,6 +117,7 @@ class GMockDependency(ExternalDependency):
     def __init__(self, environment, kwargs):
         super().__init__('gmock', environment, 'cpp', kwargs)
         self.main = kwargs.get('main', False)
+        self.ext_deps.append(ThreadDependency(environment, kwargs))
 
         # If we are getting main() from GMock, we definitely
         # want to avoid linking in main() from GTest
@@ -167,9 +167,6 @@ class GMockDependency(ExternalDependency):
 
         self.is_found = False
 
-    def need_threads(self):
-        return True
-
     def log_info(self):
         if self.prebuilt:
             return 'prebuilt'
@@ -262,6 +259,7 @@ class LLVMDependency(ConfigToolDependency):
             self._set_old_link_args()
         self.link_args = strip_system_libdirs(environment, self.link_args)
         self.link_args = self.__fix_bogus_link_args(self.link_args)
+        self.ext_deps.append(ThreadDependency(environment, kwargs))
 
     @staticmethod
     def __fix_bogus_link_args(args):
@@ -399,9 +397,6 @@ class LLVMDependency(ConfigToolDependency):
 
             self.module_details.append(mod + status)
 
-    def need_threads(self):
-        return True
-
     def log_details(self):
         if self.module_details:
             return 'modules: ' + ', '.join(self.module_details)
diff --git a/mesonbuild/dependencies/misc.py b/mesonbuild/dependencies/misc.py
index 76eccfb..5721cc3 100644
--- a/mesonbuild/dependencies/misc.py
+++ b/mesonbuild/dependencies/misc.py
@@ -385,9 +385,8 @@ class ThreadDependency(ExternalDependency):
         super().__init__('threads', environment, None, kwargs)
         self.name = 'threads'
         self.is_found = True
-
-    def need_threads(self):
-        return True
+        self.compile_args = self.clib_compiler.thread_flags(environment)
+        self.link_args = self.clib_compiler.thread_link_flags(environment)
 
 
 class Python3Dependency(ExternalDependency):