from conan.packager import ConanMultiPackager

if __name__ == "__main__":
    builder = ConanMultiPackager()
    builder.add_common_builds(pure_c=False)
    builds = []
    for settings, options, env_vars, build_requires, reference in builder.items:
        settings["cppstd"] = 14
        builds.append([settings, options, env_vars, build_requires])
    builder.builds = builds
    builder.run()

from conan.packager import ConanMultiPackager

if __name__ == "__main__":
    builder = ConanMultiPackager()
    builder.add_common_builds(pure_c=False)
    builder.run()

--- 
+++ 
@@ -3,4 +3,9 @@
 if __name__ == "__main__":
     builder = ConanMultiPackager()
     builder.add_common_builds(pure_c=False)
+    builds = []
+    for settings, options, env_vars, build_requires, reference in builder.items:
+        settings["cppstd"] = 14
+        builds.append([settings, options, env_vars, build_requires])
+    builder.builds = builds
     builder.run()
CI: Use std 14 in CI
