common/gattlib_common_adapter.c:15:17: error: implicit declaration of function 'tolower'

[brettski74]

Trying to build gattlib-0.7.2 using the tarball downloaded from https://github.com/labapart/gattlib/archive/refs/tags/0.7.2.tar.gz. Got the following output and failure during compilation:

==> Making package: gattlib 0.7.2-1 (Wed 02 Jul 2025 05:27:51 PM)
==> Checking runtime dependencies...
==> Checking buildtime dependencies...
==> Retrieving sources...
-> Found gattlib-0.7.2.tar.gz
==> Validating source files with sha256sums...
gattlib-0.7.2.tar.gz ... Passed
==> Extracting sources...
-> Extracting gattlib-0.7.2.tar.gz with bsdtar
==> Removing existing $pkgdir/ directory...
==> Starting build()...
-- Could NOT find Doxygen (missing: DOXYGEN_EXECUTABLE)
Build DBus gattlib for Bluez v5.83
Package Gattlib for development version
-- Configuring done (0.1s)
-- Generating done (0.0s)
-- Build files have been written to: /home/blg/pkgbuilds/gattlib/src/gattlib-0.7.2/build
[ 2%] Building C object dbus/CMakeFiles/gattlib.dir//common/gattlib_common_adapter.c.o
/home/blg/pkgbuilds/gattlib/src/gattlib-0.7.2/common/gattlib_common_adapter.c: In function ‘stricmp’:
/home/blg/pkgbuilds/gattlib/src/gattlib-0.7.2/common/gattlib_common_adapter.c:15:17: error: implicit declaration of function ‘tolower’ [-Wimplicit-function-declaration]
15 | int d = tolower((unsigned char)*a) - tolower((unsigned char)*b);
| ^~~~~~~
/home/blg/pkgbuilds/gattlib/src/gattlib-0.7.2/common/gattlib_common_adapter.c:8:1: note: include ‘<ctype.h>’ or provide a declaration of ‘tolower’
7 | #include "gattlib_internal.h"
+++ |+#include <ctype.h>
8 |
make[2]: *** [dbus/CMakeFiles/gattlib.dir/build.make:215: dbus/CMakeFiles/gattlib.dir//common/gattlib_common_adapter.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:267: dbus/CMakeFiles/gattlib.dir/all] Error 2
make: *** [Makefile:156: all] Error 2
==> ERROR: A failure occurred in build().
Aborting...

The build was being run from within makepkg on a recently updated Arch Linux using a PKGBUILD file with the following build commands:

build() {
cd "$srcdir/$pkgname-$pkgver"
mkdir -p build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/usr
make
}

Adding the ctype.h include as suggested in the note resolved the error and the build completed successfully. I've generated the following patch for the change:

--- gattlib-0.7.2/common/gattlib_common_adapter.c 2024-04-24 08:37:28.000000000 -0400
+++ ../src/gattlib-0.7.2/common/gattlib_common_adapter.c 2025-07-02 17:31:16.000000000 -0400
@@ -4,6 +4,7 @@

• Copyright (c) 2021-2024, Olivier Martin olivier@labapart.org
  */

+#include <ctype.h>
#include "gattlib_internal.h"

// Keep track of the allocated adapters to avoid an adapter to be freed twice.