From e7ce7c4905fd254760b1cd187752a03bc0c148ba Mon Sep 17 00:00:00 2001
From: Longjun Luo <luolongjuna@gmail.com>
Date: Sun, 30 Apr 2023 12:28:06 -0600
Subject: [PATCH] [PATCH] libcpp: suppress builtin macro redefined warnings for
__LINE__
From 0821df518b264e754d698d399f98be1a62945e32 Mon Sep 17 00:00:00 2001
From: Longjun Luo <luolongjuna@gmail.com>
Date: Thu, 12 Jan 2023 23:59:54 +0800
Subject: [PATCH] libcpp: suppress builtin macro redefined warnings for
__LINE__
As implied in
gcc.gnu.org/legacy-ml/gcc-patches/2008-09/msg00076.html,
gcc provides -Wno-builtin-macro-redefined to suppress warning when
redefining builtin macro. However, at that time, there was no
scenario for __LINE__ macro.
But, when we try to build a live-patch, we compare sections by using
-ffunction-sections. Some same functions are considered changed because
of __LINE__ macro.
At present, to detect such a changed caused by __LINE__ macro, we
have to analyse code and maintain a function list. For example,
in kpatch, check this commit
github.com/dynup/kpatch/commit/0e1b95edeafa36edb7bcf11da6d1c00f76d7e03d.
So, in this scenario, when we try to compared sections, it would
be better to support suppress builtin macro redefined warnings for
__LINE__ macro.
libcpp:
* init.cc (builtin_array): Do not always warn for a redefinition
of __LINE__.
gcc/testsuite
* gcc.dg/builtin-redefine.c: Test for redefintion warnings
for __LINE__.
* gcc.dg/builtin-redefine-1.c: New test.
---
gcc/testsuite/gcc.dg/builtin-redefine-1.c | 49 +++++++++++++++++++++++
gcc/testsuite/gcc.dg/builtin-redefine.c | 24 +++++++++--
libcpp/init.cc | 2 +-
3 files changed, 70 insertions(+), 5 deletions(-)
create mode 100755 gcc/testsuite/gcc.dg/builtin-redefine-1.c
diff --git a/gcc/testsuite/gcc.dg/builtin-redefine-1.c b/gcc/testsuite/gcc.dg/builtin-redefine-1.c
new file mode 100755
index 000000000000..c1e05b4fc7c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtin-redefine-1.c
@@ -0,0 +1,49 @@
+/* Test default warnings for redefining builtin macros. */
+
+/* { dg-do compile } */
+/* { dg-options "-D__TIMESTAMP__=x -D__TIME__=x -D__DATE__=x -D__FILE__=x -D__FILE_NAME__=x -D__BASE_FILE__=x -D__LINE__=0" } */
+
+/* Check default behavior for builtin macros redefinition. */
+
+/* { dg-message "\"__TIMESTAMP__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __TIMESTAMP__
+#error "__TIMESTAMP__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__TIME__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __TIME__
+#error "__TIME__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__DATE__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __DATE__
+#error "__DATE__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__FILE__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __FILE__
+#error "__FILE__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__FILE_NAME__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __FILE_NAME__
+#error "__FILE_NAME__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__BASE_FILE__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __BASE_FILE__
+#error "__BASE_FILE__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
+/* { dg-message "\"__LINE__\" redefined" "" {target "*-*-*"} 0 } */
+#ifndef __LINE__
+#error "__LINE__ builtin is not defined"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
+#endif
+
diff --git a/gcc/testsuite/gcc.dg/builtin-redefine.c b/gcc/testsuite/gcc.dg/builtin-redefine.c
index 882b2210992f..fa27ee9aefc8 100644
--- a/gcc/testsuite/gcc.dg/builtin-redefine.c
+++ b/gcc/testsuite/gcc.dg/builtin-redefine.c
@@ -1,9 +1,9 @@
/* Test -Wno-builtin-macro-redefined warnings. */
/* { dg-do compile } */
-/* { dg-options "-Wno-builtin-macro-redefined -U__DATE__ -D__TIME__=X" } */
+/* { dg-options "-Wno-builtin-macro-redefined -U__DATE__ -D__TIME__=X -D__LINE__=0" } */
-/* Check date, time, and datestamp built-ins warnings may be suppressed. */
+/* Check date, time, datestamp and line built-ins warnings may be suppressed. */
#if defined(__DATE__)
#error "__DATE__ is defined, but should not be (-U command line error)"
@@ -15,6 +15,11 @@
/* { dg-bogus "__TIME__ is not defined" "" { target *-*-* } .-1 } */
#endif
+#if __LINE__ != 0
+#error "__LINE__ is not defined as expected (-D command line error)"
+/* { dg-bogus "__LINE__ is not defined" "" { target *-*-* } .-1 } */
+#endif
+
#if !defined(__TIMESTAMP__)
#error "__TIMESTAMP__ is not defined (built-in macro expectation error)"
/* { dg-bogus "__TIMESTAMP__ is not defined" "" { target *-*-* } .-1 } */
@@ -53,6 +58,18 @@
#undef __TIMESTAMP__ /* Undefine while defined. */
+#undef __LINE__ /* Undefine while defined. */
+#undef __LINE__ /* Undefine while already undefined. */
+
+#define __LINE__ "1" /* Define while undefined. */
+#define __LINE__ "1" /* Re-define while defined. */ /* { dg-line line_prev } */
+
+#define __LINE__ "2" /* { dg-warning "-:\"__LINE__\" redefined" } */
+/* { dg-message "-:previous definition" "" { target *-*-* } line_prev } */
+
+#undef __LINE__ /* Undefine while defined. */
+
+
/* Check other built-ins with warnings that may be suppressed. */
#if !defined(__FILE__) || !defined(__BASE_FILE__)
@@ -66,12 +83,11 @@
/* Check selected built-ins not affected by warning suppression. */
-#if !defined(__LINE__) || !defined(__INCLUDE_LEVEL__) || !defined(__COUNTER__)
+#if !defined(__INCLUDE_LEVEL__) || !defined(__COUNTER__)
#error "Expected built-in is not defined (built-in macro expectation error)"
/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } .-1 } */
#endif
-#define __LINE__ 0 /* { dg-warning "-:\"__LINE__\" redef" } */
#define __INCLUDE_LEVEL__ 0 /* { dg-warning "-:\"__INCLUDE_LEVEL__\" redef" } */
#define __COUNTER__ 0 /* { dg-warning "-:\"__COUNTER__\" redef" } */
diff --git a/libcpp/init.cc b/libcpp/init.cc
index c508f06112af..bdeccffa0292 100644
--- a/libcpp/init.cc
+++ b/libcpp/init.cc
@@ -421,7 +421,7 @@ static const struct builtin_macro builtin_array[] =
B("__FILE__", BT_FILE, false),
B("__FILE_NAME__", BT_FILE_NAME, false),
B("__BASE_FILE__", BT_BASE_FILE, false),
- B("__LINE__", BT_SPECLINE, true),
+ B("__LINE__", BT_SPECLINE, false),
B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL, true),
B("__COUNTER__", BT_COUNTER, true),
/* Make sure to update the list of built-in
--
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