Preserve the order of internal deps in a target

We were adding them to the CompilerArgs instance in the order in which
they are specified, which is wrong because later dependencies would
override previous ones. Add them in the reverse order instead.

Closes https://github.com/mesonbuild/meson/issues/1495

3 files changed, 15 insertions, 8 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 5939488..fa9a82f 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -375,9 +375,11 @@ class Backend:
         # Set -fPIC for static libraries by default unless explicitly disabled
         if isinstance(target, build.StaticLibrary) and target.pic:
             commands += compiler.get_pic_args()
-        # Add compile args needed to find external dependencies
-        # Link args are added while generating the link command
-        for dep in target.get_external_deps():
+        # Add compile args needed to find external dependencies. Link args are
+        # added while generating the link command.
+        # NOTE: We must preserve the order in which external deps are
+        # specified, so we reverse the list before iterating over it.
+        for dep in reversed(target.get_external_deps()):
             commands += dep.get_compile_args()
             # Qt needs -fPIC for executables
             # XXX: We should move to -fPIC for all executables
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 1acfe78..e0106b2 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -1831,10 +1831,12 @@ rule FORTRAN_DEP_HACK
         # and from `include_directories:` of internal deps of the target.
         #
         # Target include dirs should override internal deps include dirs.
+        # This is handled in BuildTarget.process_kwargs()
         #
         # Include dirs from internal deps should override include dirs from
-        # external deps.
-        for i in target.get_include_dirs():
+        # external deps and must maintain the order in which they are specified.
+        # Hence, we must reverse the list so that the order is preserved.
+        for i in reversed(target.get_include_dirs()):
             basedir = i.get_curdir()
             for d in i.get_incdirs():
                 # Avoid superfluous '/.' at the end of paths when d is '.'
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index e1f7325..e512f0e 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -714,12 +714,15 @@ class Vs2010Backend(backends.Backend):
             # and from `include_directories:` of internal deps of the target.
             #
             # Target include dirs should override internal deps include dirs.
+            # This is handled in BuildTarget.process_kwargs()
             #
             # Include dirs from internal deps should override include dirs from
-            # external deps.
+            # external deps and must maintain the order in which they are
+            # specified. Hence, we must reverse so that the order is preserved.
+            #
             # These are per-target, but we still add them as per-file because we
             # need them to be looked in first.
-            for d in target.get_include_dirs():
+            for d in reversed(target.get_include_dirs()):
                 for i in d.get_incdirs():
                     curdir = os.path.join(d.get_curdir(), i)
                     args.append('-I' + self.relpath(curdir, target.subdir)) # build dir
@@ -769,7 +772,7 @@ class Vs2010Backend(backends.Backend):
 
         # Split compile args needed to find external dependencies
         # Link args are added while generating the link command
-        for d in target.get_external_deps():
+        for d in reversed(target.get_external_deps()):
             # Cflags required by external deps might have UNIX-specific flags,
             # so filter them out if needed
             d_compile_args = compiler.unix_args_to_native(d.get_compile_args())