This option is enabled by default when -Wformat option is enabled. A
user can specify -Wno-format-same-precision to disable emitting
warnings about an argument passed to printf-like function having a
different type from the one specified in the format string if the
types precisions are the same.
Signed-off-by: Daniil Stas <daniil.s...@posteo.net>
gcc/c-family/ChangeLog:
* c-format.c (check_format_types): Don't emit warnings about
type differences with the format string if
-Wno-format-same-precision is specified and the types have
the same precision.
* c.opt: Add -Wformat-same-precision option.
gcc/ChangeLog:
* doc/invoke.texi: Add -Wformat-same-precision option description.
gcc/testsuite/ChangeLog:
* c-c++-common/Wformat-same-precision-1.c: New test.
* c-c++-common/Wformat-same-precision-2.c: New test.
---
gcc/c-family/c-format.c | 2 +-
gcc/c-family/c.opt | 5 +++++
gcc/doc/invoke.texi | 8 +++++++-
gcc/testsuite/c-c++-common/Wformat-same-precision-1.c | 7 +++++++
gcc/testsuite/c-c++-common/Wformat-same-precision-2.c | 7 +++++++
5 files changed, 27 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/Wformat-same-precision-1.c
create mode 100644 gcc/testsuite/c-c++-common/Wformat-same-precision-2.c
diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
index b4cb765a9d3..07cdcefbef8 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -4243,7 +4243,7 @@ check_format_types (const substring_loc &fmt_loc,
&& (!pedantic || i < 2)
&& char_type_flag)
continue;
- if (types->scalar_identity_flag
+ if ((types->scalar_identity_flag || !warn_format_same_precision)
&& (TREE_CODE (cur_type) == TREE_CODE (wanted_type)
|| (INTEGRAL_TYPE_P (cur_type)
&& INTEGRAL_TYPE_P (wanted_type)))
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 9c151d19870..e7af7365c91 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -656,6 +656,11 @@ C ObjC C++ LTO ObjC++ Warning Alias(Wformat-overflow=, 1,
0) IntegerRange(0, 2)
Warn about function calls with format strings that write past the end
of the destination region. Same as -Wformat-overflow=1.
+Wformat-same-precision
+C ObjC C++ ObjC++ Var(warn_format_same_precision) Warning LangEnabledBy(C ObjC
C++ ObjC++,Wformat=,warn_format >= 1, 0)
+Warn about type differences with the format string even if the types
+precision is the same.
+
Wformat-security
C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++
ObjC++,Wformat=, warn_format >= 2, 0)
Warn about possible security problems with format functions.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ba98eab68a5..8833f257d75 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -347,7 +347,7 @@ Objective-C and Objective-C++ Dialects}.
-Werror -Werror=* -Wexpansion-to-defined -Wfatal-errors @gol
-Wfloat-conversion -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args @gol
--Wformat-nonliteral -Wformat-overflow=@var{n} @gol
+-Wformat-nonliteral -Wformat-overflow=@var{n} -Wformat-same-precision @gol
-Wformat-security -Wformat-signedness -Wformat-truncation=@var{n} @gol
-Wformat-y2k -Wframe-address @gol
-Wframe-larger-than=@var{byte-size} -Wno-free-nonheap-object @gol
@@ -6054,6 +6054,12 @@ If @option{-Wformat} is specified, also warn if the
format string is not a
string literal and so cannot be checked, unless the format function
takes its format arguments as a @code{va_list}.
+@item -Wformat-same-precision
+@opindex Wformat-same-precision
+@opindex Wno-format-same-precision
+If @option{-Wformat} is specified, warn about type differences with the format
+string even if the types precision is the same.
+
@item -Wformat-security
@opindex Wformat-security
@opindex Wno-format-security
diff --git a/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c
b/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c
new file mode 100644
index 00000000000..fbc11e4200a
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wformat-same-precision-1.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-options "-Wformat" } */
+
+void test ()
+{
+ __builtin_printf ("%lu\n", (long long) 1); /* { dg-warning "expects argument
of type" } */
+}
diff --git a/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c
b/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c
new file mode 100644
index 00000000000..17e643e0441
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Wformat-same-precision-2.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-options "-Wformat -Wno-format-same-precision" } */
+
+void test ()
+{
+ __builtin_printf ("%lu\n", (long long) 1); /* { ! dg-warning "expects
argument of type" } */
+}
--
2.33.0
