userland: start per-directory flags with userland/gcc

build-userland

@@ -17,6 +17,8 @@ class Main(common.BuildCliFunction):
 Build our compiled userland examples.
 '''
         )
+        self.default_cstd = 'c11'
+        self.default_cxxstd = 'c++17'
         self.add_argument(
             '--has-package',
             action='append',
@@ -45,11 +47,12 @@ Default: build all examples that have their package dependencies met, e.g.:
         in_path,
         out_path,
         ccflags,
-        extra_deps=None,
-        link=True,
-        extra_objs=None,
-        std=None,
         ccflags_after=None,
+        cstd=None,
+        cxxstd=None,
+        extra_deps=None,
+        extra_objs=None,
+        link=True,
         raise_on_failure=True,
         thread_limiter=None,
     ):
@@ -69,15 +72,19 @@ Default: build all examples that have their package dependencies met, e.g.:
                 do_compile = True
                 if in_ext == self.env['c_ext']:
                     cc = self.env['gcc']
-                    if std is None:
-                        std = 'c11'
+                    if cstd is None:
+                        std = self.default_cstd
+                    else:
+                        std = cstd
                     ccflags.extend([
                         '-fopenmp', LF,
                     ])
                 elif in_ext == self.env['cxx_ext']:
                     cc = self.env['gxx']
-                    if std is None:
-                        std = 'c++17'
+                    if cxxstd is None:
+                        std = self.default_cxxstd
+                    else:
+                        std = cxxstd
                 else:
                     do_compile = False
                 if do_compile:
@@ -121,7 +128,6 @@ Default: build all examples that have their package dependencies met, e.g.:
             '-Werror', LF,
             '-Wextra', LF,
             '-Wno-unused-function', LF,
-            '-pedantic', LF,
             '-ggdb3', LF,
         ]
         if self.env['static']:
@@ -183,6 +189,15 @@ Default: build all examples that have their package dependencies met, e.g.:
                         dirpath_relative_root
                     )
                     os.makedirs(out_dir, exist_ok=True)
+                    ccflags_dir = ccflags.copy()
+                    if dirpath_relative_root_components == ['gcc']:
+                        cstd = 'gnu11'
+                        cxxstd = 'gnu++17'
+                    else:
+                        cstd = self.default_cstd
+                        cxxstd = self.default_cxxstd
+                        # -pedantic complains even if we use -std=gnu11.
+                        ccflags_dir.extend(['-pedantic', LF])
                     for in_filename in in_filenames:
                         in_path = os.path.join(path, in_filename)
                         in_name, in_ext = os.path.splitext(in_filename)
@@ -191,7 +206,7 @@ Default: build all examples that have their package dependencies met, e.g.:
                             in_name + self.env['userland_build_ext']
                         )
                         pkg_key = in_name.split('_')[0]
-                        ccflags_file = ccflags.copy()
+                        ccflags_file = ccflags_dir.copy()
                         ccflags_after = []
                         if pkg_key in pkgs:
                             if pkg_key not in has_packages:
@@ -221,13 +236,15 @@ Default: build all examples that have their package dependencies met, e.g.:
                         thread = threading.Thread(
                             target=self._build_one,
                             kwargs={
-                                'in_path':in_path,
-                                'out_path':out_path,
-                                'ccflags':ccflags_file,
-                                'extra_objs':[common_obj],
-                                'ccflags_after':ccflags_after,
-                                'raise_on_failure':False,
-                                'thread_limiter':thread_limiter,
+                                'in_path': in_path,
+                                'out_path': out_path,
+                                'ccflags': ccflags_file,
+                                'cstd': cstd,
+                                'cxxstd': cxxstd,
+                                'extra_objs': [common_obj],
+                                'ccflags_after': ccflags_after,
+                                'raise_on_failure': False,
+                                'thread_limiter': thread_limiter,
                             }
                         )
                         thread.start()

userland/gcc/empty_struct.c

@@ -0,0 +1,11 @@
+/* Empty struct */
+
+#include <assert.h>
+#include <stdlib.h>
+
+int main(void) {
+    struct s {};
+    struct s s0;
+    assert(sizeof(s0) == 0);
+    return EXIT_SUCCESS;
+}