From ecb076ba002afb6a6678983dd02ac53d9b751f12 Mon Sep 17 00:00:00 2001
From: Xavier Claessens <xavier.claessens@collabora.com>
Date: Tue, 3 Mar 2020 10:50:15 -0500
Subject: [PATCH] qt5: Add has_tools() method

---
 docs/markdown/Qt5-module.md            | 22 ++++++++++++++++++++++
 docs/markdown/snippets/qt_has_tools.md | 10 ++++++++++
 mesonbuild/modules/qt.py               | 21 ++++++++++++++++++++-
 test cases/frameworks/4 qt/meson.build |  1 +
 4 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 docs/markdown/snippets/qt_has_tools.md

diff --git a/docs/markdown/Qt5-module.md b/docs/markdown/Qt5-module.md
index 3a5195485..f1c2f6c00 100644
--- a/docs/markdown/Qt5-module.md
+++ b/docs/markdown/Qt5-module.md
@@ -23,6 +23,28 @@ This method generates the necessary targets to build translation files with lrel
  - `install_dir` directory to install to (optional).
  - `build_by_default` when set to true, to have this target be built by default, that is, when invoking plain ninja; the default value is false (optional).
 
+## has_tools
+
+This method returns `true` if all tools used by this module are found, `false`
+otherwise.
+
+It should be used to compile optional Qt code:
+```meson
+qt5 = import('qt5')
+if qt5.has_tools(required: get_option('qt_feature'))
+  moc_files = qt5.preprocess(...)
+  ...
+endif
+```
+
+This method takes the following keyword arguments:
+- `required`: by default, `required` is set to `false`. If `required` is set to
+  `true` or an enabled [`feature`](Build-options.md#features) and some tools are
+  missing Meson will abort.
+- `method`: method used to find the Qt dependency (`auto` by default).
+
+*Since: 0.54.0*
+
 ## Dependencies
 
 See [Qt dependencies](Dependencies.md#qt4-qt5)
diff --git a/docs/markdown/snippets/qt_has_tools.md b/docs/markdown/snippets/qt_has_tools.md
new file mode 100644
index 000000000..3569ecb96
--- /dev/null
+++ b/docs/markdown/snippets/qt_has_tools.md
@@ -0,0 +1,10 @@
+## Added `has_tools` method to qt module
+
+It should be used to compile optional Qt code:
+```meson
+qt5 = import('qt5')
+if qt5.has_tools(required: get_option('qt_feature'))
+  moc_files = qt5.preprocess(...)
+  ...
+endif
+```
diff --git a/mesonbuild/modules/qt.py b/mesonbuild/modules/qt.py
index 6887bc744..76edb7ef1 100644
--- a/mesonbuild/modules/qt.py
+++ b/mesonbuild/modules/qt.py
@@ -19,7 +19,8 @@ from ..mesonlib import MesonException, Popen_safe, extract_as_list, File
 from ..dependencies import Dependency, Qt4Dependency, Qt5Dependency
 import xml.etree.ElementTree as ET
 from . import ModuleReturnValue, get_include_args, ExtensionModule
-from ..interpreterbase import permittedKwargs, FeatureNew, FeatureNewKwargs
+from ..interpreterbase import noPosargs, permittedKwargs, FeatureNew, FeatureNewKwargs
+from ..interpreter import extract_required_kwarg
 
 _QT_DEPS_LUT = {
     4: Qt4Dependency,
@@ -32,6 +33,7 @@ class QtBaseModule(ExtensionModule):
 
     def __init__(self, interpreter, qt_version=5):
         ExtensionModule.__init__(self, interpreter)
+        self.snippets.add('has_tools')
         self.qt_version = qt_version
 
     def _detect_tools(self, env, method):
@@ -117,6 +119,23 @@ class QtBaseModule(ExtensionModule):
         except Exception:
             return []
 
+    @noPosargs
+    @permittedKwargs({'method', 'required'})
+    @FeatureNew('qt.has_tools', '0.54.0')
+    def has_tools(self, interpreter, state, args, kwargs):
+        method = kwargs.get('method', 'auto')
+        disabled, required, feature = extract_required_kwarg(kwargs, state.subproject, default=False)
+        if disabled:
+            mlog.log('qt.has_tools skipped: feature', mlog.bold(feature), 'disabled')
+            return False
+        self._detect_tools(state.environment, method)
+        for tool in (self.moc, self.uic, self.rcc, self.lrelease):
+            if not tool.found():
+                if required:
+                    raise MesonException('Qt tools not found')
+                return False
+        return True
+
     @FeatureNewKwargs('qt.preprocess', '0.49.0', ['uic_extra_arguments'])
     @FeatureNewKwargs('qt.preprocess', '0.44.0', ['moc_extra_arguments'])
     @FeatureNewKwargs('qt.preprocess', '0.49.0', ['rcc_extra_arguments'])
diff --git a/test cases/frameworks/4 qt/meson.build b/test cases/frameworks/4 qt/meson.build
index 7934572db..8f18809bd 100644
--- a/test cases/frameworks/4 qt/meson.build	
+++ b/test cases/frameworks/4 qt/meson.build	
@@ -42,6 +42,7 @@ foreach qt : ['qt4', 'qt5']
   qtdep = dependency(qt, modules : qt_modules, main : true, private_headers: true, required : required, method : get_option('method'))
   if qtdep.found()
     qtmodule = import(qt)
+    assert(qtmodule.has_tools())
 
     # The following has two resource files because having two in one target
     # requires you to do it properly or you get linker symbol clashes.