From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99DBAC7618B for ; Thu, 25 Jul 2019 15:47:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6013F22BF5 for ; Thu, 25 Jul 2019 15:47:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="ean5MHBi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389479AbfGYPrd (ORCPT ); Thu, 25 Jul 2019 11:47:33 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:41864 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387443AbfGYPrc (ORCPT ); Thu, 25 Jul 2019 11:47:32 -0400 Received: by mail-pl1-f195.google.com with SMTP id m9so23476109pls.8 for ; Thu, 25 Jul 2019 08:47:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9YuwL0GVl7nYF4rNeboTYpwrDtxx+jHFRpSdYJwSITY=; b=ean5MHBizDZdsUUIRHt5FbVJgYeO7FgMb1a9hVK6yxi1fz7+Hkj1uslGVTWDI7Vh1T 5wzB6dpLbYY/mphzmqXfzrbQaMHmL+Xf94SnquKlzEY6CZO8XJIgCS6+h74m0kPyFAJ3 uC11JMPrNVdsRcN6TFJsvryEWLRy9Uz1b2X+A= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9YuwL0GVl7nYF4rNeboTYpwrDtxx+jHFRpSdYJwSITY=; b=BoB6CGZ3mSrmn9nUu5F3BLdFeeALdprMHwJ6rqTTCE73LR02HOOcVBr0ePdwtPHK1C TYZVG8wA4Fvc4Yh6zLDybsXFnB3sB6c8saXGCUtJztH7uh00zrXn9YHvoG+tZPi0mgy3 1BgMwu+rKYGr/fjGkraphg1g4YXsmiI9q6uM6ztgEDnxet1xoXZwvloxEMmxsZvJjw1n osORrcqnip9Y+rFJiUVKdzFfdMuIgbg99rWTFOdPSbA2lvC8gI73B0/wRrDA21RxoiQX fSm4xb+3REaA2TdoqRW3hNAxn1x2gC7izLTGuIBUlxqntcJgiGCosJvrKRdt0o2z44eu Za9Q== X-Gm-Message-State: APjAAAUttNjyeyNA3z/Uei0TGUxtl5qBdNTT7nl2wFAYxu24WfpO00Uj gLvQ4SwbD0Ym2DVP9LqgSs4fyg== X-Google-Smtp-Source: APXvYqxJF0UtobMLDtssdzA6jMO8gxhwf/YcI24LGS7/vAbwXaFc1qoYW+wkdyjZUFQJ5p6EXiGt9Q== X-Received: by 2002:a17:902:f082:: with SMTP id go2mr95978482plb.25.1564069651837; Thu, 25 Jul 2019 08:47:31 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:202:1:fa53:7765:582b:82b9]) by smtp.gmail.com with ESMTPSA id r1sm47083788pgv.70.2019.07.25.08.47.31 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 25 Jul 2019 08:47:31 -0700 (PDT) From: Stephen Boyd To: Masahiro Yamada , Michal Marek Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, Peter Smith , Nathan Chancellor , Nick Desaulniers , Douglas Anderson Subject: [PATCH v2] kbuild: Check for unknown options with cc-option usage in Kconfig and clang Date: Thu, 25 Jul 2019 08:47:30 -0700 Message-Id: <20190725154730.80169-1-swboyd@chromium.org> X-Mailer: git-send-email 2.22.0.657.g960e92d24f-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the particular version of clang a user has doesn't enable -Werror=unknown-warning-option by default, even though it is the default[1], then make sure to pass the option to the Kconfig cc-option command so that testing options from Kconfig files works properly. Otherwise, depending on the default values setup in the clang toolchain we will silently assume options such as -Wmaybe-uninitialized are supported by clang, when they really aren't. A compilation issue only started happening for me once commit 589834b3a009 ("kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS") was applied on top of commit b303c6df80c9 ("kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig"). This leads kbuild to try and test for the existence of the -Wmaybe-uninitialized flag with the cc-option command in scripts/Kconfig.include, and it doesn't see an error returned from the option test so it sets the config value to Y. Then the Makefile tries to pass the unknown option on the command line and -Werror=unknown-warning-option catches the invalid option and breaks the build. Before commit 589834b3a009 ("kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS") the build works fine, but any cc-option test of a warning option in Kconfig files silently evaluates to true, even if the warning option flag isn't supported on clang. Note: This doesn't change cc-option usages in Makefiles because those use a different rule that includes KBUILD_CFLAGS by default (see the __cc-option command in scripts/Kbuild.incluide). The KBUILD_CFLAGS variable already has the -Werror=unknown-warning-option flag set. Thanks to Doug for pointing out the different rule. [1] https://clang.llvm.org/docs/DiagnosticsReference.html#wunknown-warning-option Cc: Peter Smith Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Douglas Anderson Reviewed-by: Nathan Chancellor Signed-off-by: Stephen Boyd --- Changes from v1: * Reworded commit text a bit * Added Reviewed-by tag Makefile | 5 +++++ scripts/Kconfig.include | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 9be5834073f8..28177674178a 100644 --- a/Makefile +++ b/Makefile @@ -517,6 +517,8 @@ ifdef building_out_of_srctree { echo "# this is build directory, ignore it"; echo "*"; } > .gitignore endif +KCONFIG_CC_OPTION_FLAGS := -Werror + ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) ifneq ($(CROSS_COMPILE),) CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) @@ -531,11 +533,14 @@ ifeq ($(shell $(AS) --version 2>&1 | head -n 1 | grep clang),) CLANG_FLAGS += -no-integrated-as endif CLANG_FLAGS += -Werror=unknown-warning-option +KCONFIG_CC_OPTION_FLAGS += -Werror=unknown-warning-option KBUILD_CFLAGS += $(CLANG_FLAGS) KBUILD_AFLAGS += $(CLANG_FLAGS) export CLANG_FLAGS endif +export KCONFIG_CC_OPTION_FLAGS + # The expansion should be delayed until arch/$(SRCARCH)/Makefile is included. # Some architectures define CROSS_COMPILE in arch/$(SRCARCH)/Makefile. # CC_VERSION_TEXT is referenced from Kconfig (so it needs export), diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include index 8a5c4d645eb1..144e83e7cb81 100644 --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -25,7 +25,7 @@ failure = $(if-success,$(1),n,y) # $(cc-option,) # Return y if the compiler supports , n otherwise -cc-option = $(success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null) +cc-option = $(success,$(CC) $(KCONFIG_CC_OPTION_FLAGS) $(1) -E -x c /dev/null -o /dev/null) # $(ld-option,) # Return y if the linker supports , n otherwise -- Sent by a computer through tubes