[Mesa-dev] [PATCH mesa 6/6] meson+autotools: get rid of spammy GCC warning -Wformat-truncation

Eric Engestrom eric.engestrom at intel.com
Fri Sep 21 13:50:41 UTC 2018

That warning fires every time a string function takes an argument that
could possibly be longer than its max output, which triggers all over
the place, especially when working with file paths ("what if every file
path is MAX_PATH long?" is what GCC is saying, which is really annoying
when we *know* that "/dev/dri/cardN" is not gonna be 4096 char long and
it's safe to store it in a 32-char array).

Anyway, we either add a ton of dead code all over the place to make GCC
happy, or we get rid of its spam. I chose the latter.

Signed-off-by: Eric Engestrom <eric.engestrom at intel.com>
 configure.ac | 2 ++
 meson.build  | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 7583a375ad75454215e5..34689826c98e116d4ee7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -307,6 +307,7 @@ AX_CHECK_COMPILE_FLAG([-Werror=missing-prototypes],            [CFLAGS="$CFLAGS
 AX_CHECK_COMPILE_FLAG([-Wmissing-prototypes],                  [CFLAGS="$CFLAGS -Wmissing-prototypes"])
 dnl Dylan Baker: gcc and clang always accepr -Wno-*, hence check for the original warning, then set the no-* flag
 AX_CHECK_COMPILE_FLAG([-Wmissing-field-initializers],          [CFLAGS="$CFLAGS -Wno-missing-field-initializers"])
+AX_CHECK_COMPILE_FLAG([-Wformat-truncation],                   [CFLAGS="$CFLAGS -Wno-format-truncation"])
 AX_CHECK_COMPILE_FLAG([-fno-math-errno],                       [CFLAGS="$CFLAGS -fno-math-errno"])
 AX_CHECK_COMPILE_FLAG([-fno-trapping-math],                    [CFLAGS="$CFLAGS -fno-trapping-math"])
@@ -321,6 +322,7 @@ AX_CHECK_COMPILE_FLAG([-fno-math-errno],                       [CXXFLAGS="$CXXFL
 AX_CHECK_COMPILE_FLAG([-fno-trapping-math],                    [CXXFLAGS="$CXXFLAGS -fno-trapping-math"])
 AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],                   [VISIBILITY_CXXFLAGS="-fvisibility=hidden"])
 AX_CHECK_COMPILE_FLAG([-Wmissing-field-initializers],          [CXXFLAGS="$CXXFLAGS -Wno-missing-field-initializers"])
+AX_CHECK_COMPILE_FLAG([-Wformat-truncation],                   [CXXFLAGS="$CXXFLAGS -Wno-format-truncation"])
 # Flags to help ensure that certain portions of the code -- and only those
diff --git a/meson.build b/meson.build
index 863962186caa6afe8ae4..094242692d9f9d03440e 100644
--- a/meson.build
+++ b/meson.build
@@ -791,7 +791,7 @@ foreach a : ['-Wall', '-Werror=implicit-function-declaration',
-foreach a : ['missing-field-initializers']
+foreach a : ['missing-field-initializers', 'format-truncation']
   if cc.has_argument('-W' + a)
     c_args += '-Wno-' + a
@@ -814,7 +814,7 @@ endforeach
 # For some reason, the test for -Wno-foo always succeeds with gcc, even if the
 # option is not supported. Hence, check for -Wfoo instead.
-foreach a : ['non-virtual-dtor', 'missing-field-initializers']
+foreach a : ['non-virtual-dtor', 'missing-field-initializers', 'format-truncation']
   if cpp.has_argument('-W' + a)
     cpp_args += '-Wno-' + a

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