2 files changed, 6 insertions, 2 deletions
diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index e49793e..a77047b 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -23,6 +23,7 @@ import subprocess
 from ..mesonlib import MesonException, get_meson_script
 from ..mesonlib import get_compiler_for_source, classify_unity_sources
 from ..compilers import CompilerArgs
+from collections import OrderedDict
 
 class CleanTrees:
     '''
@@ -574,7 +575,7 @@ class Backend:
         return newargs
 
     def get_build_by_default_targets(self):
-        result = {}
+        result = OrderedDict()
         # Get all build and custom targets that must be built by default
         for name, t in self.build.get_targets().items():
             if t.build_by_default or t.install or t.build_always:
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index dfb5600..98a2110 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -2351,7 +2351,10 @@ rule FORTRAN_DEP_HACK
         cmds = []
         for (k, v) in self.environment.coredata.user_options.items():
             cmds.append('-D' + k + '=' + (v.value if isinstance(v.value, str) else str(v.value).lower()))
-        return cmds
+        # The order of these arguments must be the same between runs of Meson
+        # to ensure reproducible output. The order we pass them shouldn't
+        # affect behaviour in any other way.
+        return sorted(cmds)
 
     # For things like scan-build and other helper tools we might have.
     def generate_utils(self, outfile):