Make the dependency order deterministic. (#3927)

We were using sets to store the dependencies. Just switch to
OrderedSet.

Fixes #3922.

mesonbuild/backend/ninjabackend.py

@@ -73,8 +73,8 @@ class NinjaBuildElement:
             self.infilenames = [infilenames]
         else:
             self.infilenames = infilenames
-        self.deps = set()
-        self.orderdeps = set()
+        self.deps = OrderedSet()
+        self.orderdeps = OrderedSet()
         self.elems = []
         self.all_outputs = all_outputs
 

run_unittests.py

@@ -3587,6 +3587,19 @@ endian = 'little'
         self.build()
         self.run_tests()
 
+    def test_deterministic_dep_order(self):
+        '''
+        Test that the dependencies are always listed in a deterministic order.
+        '''
+        testdir = os.path.join(self.common_test_dir, '206 dep order')
+        self.init(testdir)
+        with open(os.path.join(self.builddir, 'build.ninja')) as bfile:
+            for line in bfile:
+                if 'build myexe:' in line or 'build myexe.exe:' in line:
+                    self.assertIn('liblib1.a liblib2.a', line)
+                    return
+        raise RuntimeError('Could not find the build rule')
+
     @skipIfNoPkgconfig
     def test_usage_external_library(self):
         '''

test cases/common/206 dep order/meson.build

@@ -0,0 +1,8 @@
+project('myexe', 'c')
+
+lib1 = static_library('lib1', 'lib1.c')
+lib2 = static_library('lib2', 'lib2.c')
+
+executable('myexe',
+           'myexe.c',
+           link_with: [lib1, lib2])

test cases/common/206 dep order/myexe.c

@@ -0,0 +1,3 @@
+int main(int ac, char** av) {
+    return 0;
+}