Use -isystem instead of -idirafter

mesonbuild/compilers/compilers.py

@@ -420,7 +420,7 @@ class CompilerArgs(list):
     # Arg prefixes that override by prepending instead of appending
     prepend_prefixes = ('-I', '-L')
     # Arg prefixes and args that must be de-duped by returning 2
-    dedup2_prefixes = ('-I', '-L', '-D', '-U')
+    dedup2_prefixes = ('-I', '-isystem', '-L', '-D', '-U')
     dedup2_suffixes = ()
     dedup2_args = ()
     # Arg prefixes and args that must be de-duped by returning 1
@@ -548,6 +548,22 @@ class CompilerArgs(list):
                 # Last occurrence of a library
                 new.insert(group_end + 1, '-Wl,--end-group')
                 new.insert(group_start, '-Wl,--start-group')
+        # Remove system/default include paths added with -isystem
+        if hasattr(self.compiler, 'get_default_include_dirs'):
+            default_dirs = self.compiler.get_default_include_dirs()
+            bad_idx_list = []
+            for i, each in enumerate(new):
+                # Remove the -isystem and the path if the path is a dafault path
+                if (each == '-isystem' and
+                        i < (len(new) - 1) and
+                        new[i + 1] in default_dirs):
+                    bad_idx_list += [i, i + 1]
+                elif each.startswith('-isystem=') and each[9:] in default_dirs:
+                    bad_idx_list += [i]
+                elif each.startswith('-isystem') and each[8:] in default_dirs:
+                    bad_idx_list += [i]
+            for i in reversed(bad_idx_list):
+                new.pop(i)
         return self.compiler.unix_args_to_native(new)
 
     def append_direct(self, arg):

mesonbuild/dependencies/base.py

@@ -139,11 +139,7 @@ class Dependency:
         system_args = []
         for i in self.compile_args:
             if i.startswith('-I') or i.startswith('/I'):
-                # -isystem and -idirafter, both mark directories as system
+                system_args += ['-isystem' + i[2:]]
-                # directories. However, both affect the search oder, which
-                # can lead to nasty bugs with -isystem:
-                # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70129
-                system_args += ['-idirafter' + i[2:]]
             else:
                 system_args += [i]
 

run_unittests.py

@@ -447,6 +447,8 @@ class InternalTests(unittest.TestCase):
         ## Test --start/end-group
         linker = mesonbuild.linkers.GnuDynamicLinker([], MachineChoice.HOST, 'fake', '-Wl,')
         gcc = mesonbuild.compilers.GnuCCompiler([], 'fake', mesonbuild.compilers.CompilerType.GCC_STANDARD, False, MachineChoice.HOST, linker=linker)
+        ## Ensure that the fake compiler is never called by overriding the relevant function
+        gcc.get_default_include_dirs = lambda: ['/usr/include', '/usr/share/include', '/usr/local/include']
         ## Test that 'direct' append and extend works
         l = cargsfunc(gcc, ['-Lfoodir', '-lfoo'])
         self.assertEqual(l.to_native(copy=True), ['-Lfoodir', '-Wl,--start-group', '-lfoo', '-Wl,--end-group'])
@@ -469,6 +471,20 @@ class InternalTests(unittest.TestCase):
         l.append('-Wl,-ldl')
         self.assertEqual(l.to_native(copy=True), ['-Lfoo', '-Lfoodir', '-Wl,--start-group', '-lfoo', '-Lbardir', '-lbar', '-lbar', '/libbaz.a', '-Wl,--export-dynamic', '-Wl,-ldl', '-Wl,--end-group'])
 
+    def test_compiler_args_remove_system(self):
+        cargsfunc = mesonbuild.compilers.CompilerArgs
+        ## Test --start/end-group
+        linker = mesonbuild.linkers.GnuDynamicLinker([], MachineChoice.HOST, 'fake', '-Wl,')
+        gcc = mesonbuild.compilers.GnuCCompiler([], 'fake', mesonbuild.compilers.CompilerType.GCC_STANDARD, False, MachineChoice.HOST, linker=linker)
+        ## Ensure that the fake compiler is never called by overriding the relevant function
+        gcc.get_default_include_dirs = lambda: ['/usr/include', '/usr/share/include', '/usr/local/include']
+        ## Test that 'direct' append and extend works
+        l = cargsfunc(gcc, ['-Lfoodir', '-lfoo'])
+        self.assertEqual(l.to_native(copy=True), ['-Lfoodir', '-Wl,--start-group', '-lfoo', '-Wl,--end-group'])
+        ## Test that to_native removes all system includes
+        l += ['-isystem/usr/include', '-isystem=/usr/share/include', '-DSOMETHING_IMPORTANT=1', '-isystem', '/usr/local/include']
+        self.assertEqual(l.to_native(copy=True), ['-Lfoodir', '-Wl,--start-group', '-lfoo', '-Wl,--end-group', '-DSOMETHING_IMPORTANT=1'])
+
     def test_string_templates_substitution(self):
         dictfunc = mesonbuild.mesonlib.get_filenames_templates_dict
         substfunc = mesonbuild.mesonlib.substitute_values