Re: [gtk-osx-users] Pango/break.c error: unannotated fall-through between switch labels.

[John Ralls <jralls ceridwen us>]

> On Sep 27, 2020, at 1:42 AM, Pascal <p p14 orange fr> wrote:
>
> Hello,
>
> I've upgraded to Xcode 12.
> One good news is that Python comes in version 3.8.2.
>
> But I've got an issue when compiling pango:
>
> *** Configuring pango *** [22/32]
> meson --prefix /usr/local/xnadalib-2020 --libdir lib  --wrap-mode=nofallback 
> /usr/local/src-2020/pango-1.44.7
> The Meson build system
> Version: 0.55.0
> Source dir: /usr/local/src-2020/pango-1.44.7
> Build dir: /usr/local/src-2020/cache/jhbuild/build/pango-1.44.7
> ...
> *** Building pango *** [22/32]
> ninja  
> [3/126] Compiling C object pango/libpango-1.0.0.dylib.p/break.c.o
> FAILED: pango/libpango-1.0.0.dylib.p/break.c.o 
> /Applications/Xcode.app/Contents/Developer/usr/bin/gcc -Ipango/libpango-1.0.0.dylib.p -Ipango 
> -I../../../../pango-1.44.7/pango -I. -I../../../../pango-1.44.7 -I/usr/local/xnadalib-2020/include/glib-2.0 
> -I/usr/local/xnadalib-2020/lib/glib-2.0/include -I/usr/local/xnadalib-2020/include/fribidi 
> -I/usr/local/xnadalib-2020/include/harfbuzz -I/usr/local/xnadalib-2020/include/freetype2 
> -I/usr/local/xnadalib-2020/include/libpng16 -I/usr/local/xnadalib-2020/include/cairo 
> -I/usr/local/xnadalib-2020/include/pixman-1 
> -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include
>  -I/usr/local/xnadalib-2020/include -Xclang -fcolor-diagnostics -pipe -Wall -Winvalid-pch -std=gnu99 -O2 -g 
> -D_POSIX_C_SOURCE=200809L -D_POSIX_THREAD_SAFE_FUNCTIONS -D_GNU_SOURCE -arch x86_64 -isysroot 
> /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk 
> -mmacosx-version-min=10.15 -g -O0 -ggdb3 -arch x86_64 -isysroot /Applications/Xcod
> e.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -g -O0 -ggdb3 
> -Wimplicit-function-declaration -Wstrict-prototypes -Wmissing-prototypes -Wnested-externs 
> -Wold-style-definition -Wno-int-conversion -fno-strict-aliasing -Wpointer-arith -Wmissing-declarations 
> -Wformat=2 -Wformat-nonliteral -Wformat-security -Wunused -Wcast-align -Wmissing-noreturn 
> -Wmissing-format-attribute -Wmissing-include-dirs -Wno-uninitialized -Wno-shadow -Werror=implicit 
> -Werror=implicit-fallthrough -Werror=nonnull -Werror=init-self -Werror=main -Werror=missing-braces 
> -Werror=sequence-point -Werror=return-type -Werror=trigraphs -Werror=array-bounds -Werror=write-strings 
> -Werror=address -Werror=int-to-pointer-cast -Werror=pointer-to-int-cast -Werror=empty-body 
> -Werror=write-strings -Wundef -Werror=redundant-decls -fvisibility=hidden -DPANGO_ENABLE_DEBUG 
> '-DG_LOG_DOMAIN="Pango"' -DG_LOG_USE_STRUCTURED=1 -DPANGO_COMPILATION 
> '-DSYSCONFDIR="/usr/local/xnadalib-2020/etc"' '-DLIBDIR="/usr/loca
> l/xnadalib-2020/lib"' -MD -MQ pango/libpango-1.0.0.dylib.p/break.c.o -MF 
> pango/libpango-1.0.0.dylib.p/break.c.o.d -o pango/libpango-1.0.0.dylib.p/break.c.o -c 
> ../../../../pango-1.44.7/pango/break.c
> ../../../../pango-1.44.7/pango/break.c:409:4: error: unannotated fall-through between switch labels 
> [-Werror,-Wimplicit-fallthrough]
>          case G_UNICODE_CONTROL:
>          ^
> ../../../../pango-1.44.7/pango/break.c:409:4: note: insert '__attribute__((fallthrough));' to silence this 
> warning
>          case G_UNICODE_CONTROL:
>          ^
>          __attribute__((fallthrough)); 
> ../../../../pango-1.44.7/pango/break.c:409:4: note: insert 'break;' to avoid fall-through
>          case G_UNICODE_CONTROL:
>          ^
>          break; 
> ../../../../pango-1.44.7/pango/break.c:426:4: error: unannotated fall-through between switch labels 
> [-Werror,-Wimplicit-fallthrough]
>          case G_UNICODE_OTHER_LETTER:
>          ^
> ../../../../pango-1.44.7/pango/break.c:426:4: note: insert '__attribute__((fallthrough));' to silence this 
> warning
>          case G_UNICODE_OTHER_LETTER:
>          ^
>          __attribute__((fallthrough)); 
> ../../../../pango-1.44.7/pango/break.c:426:4: note: insert 'break;' to avoid fall-through
>          case G_UNICODE_OTHER_LETTER:
>          ^
>          break; 
> ../../../../pango-1.44.7/pango/break.c:598:3: error: unannotated fall-through between switch labels 
> [-Werror,-Wimplicit-fallthrough]
>                case G_UNICODE_LINE_SEPARATOR:
>                ^
> ../../../../pango-1.44.7/pango/break.c:598:3: note: insert '__attribute__((fallthrough));' to silence this 
> warning
>                case G_UNICODE_LINE_SEPARATOR:
>                ^
>                __attribute__((fallthrough)); 
> ../../../../pango-1.44.7/pango/break.c:598:3: note: insert 'break;' to avoid fall-through
>                case G_UNICODE_LINE_SEPARATOR:
>                ^
>                break; 
> 3 errors generated.
> [8/126] Generating pango-enum-types.c with a meson_exe.py custom command
> ninja: build stopped: subcommand failed.
> *** Error during phase build of pango: ########## Error running ninja   *** [22/32]
>
> Is it really related to Xcode update?

Yup.

Clang apple-version-12 no longer supports the comment-based fall through annotation to silence that warning 
(which the pango devs enable). Pango 1.46 switches to use G_GNUC_FALLTHROUGH that's defined to 
__annotation__((fallthrough)) in glib, but only for gcc until glib-2.65. I'll get an update out as soon as 
the test build finishes.

Regards,
John Ralls