FTBFS - Cast function type mismatch

[melizasw]

Shows up with Clang 19.1.2 but not with Clang 16.0.6. This is when building Swift 5.8.1, but it looks like this code hasn't changed since then.

swift-corelibs-libdispatch/src/apply.c:366:4: error: cast from 'dispatch_function_t' (aka 'void ()(void * _Nullable)') to 'dispatch_apply_function_t' (aka 'void ()(void *, unsigned long)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
366 | (dispatch_apply_function_t)_dispatch_Block_invoke(work));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[ggardet]

Fails also with 5.10.1 and Clang 19.1.4:

[   19s] FAILED: src/CMakeFiles/dispatch.dir/apply.c.o 
[   19s] /usr/bin/clang -DDISPATCH_USE_DTRACE=0 -DHAVE_CONFIG_H -D_GNU_SOURCE=1 -Ddispatch_EXPORTS -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/build -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/src -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/build/src -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/private -I/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/src/BlocksRuntime -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto -g -O2 -g -DNDEBUG -std=gnu11 -fPIC -fvisibility=hidden -Werror -Wall -Wextra -Warray-bounds-pointer-arithmetic -Wassign-enum -Watomic-properties -Wcomma -Wconditional-uninitialized -Wconversion -Wcovered-switch-default -Wdate-time -Wdeprecated -Wdocumentation -Wdouble-promotion -Wduplicate-enum -Wexpansion-to-defined -Wfloat-equal -Widiomatic-parentheses -Winfinite-recursion -Wmissing-prototypes -Wnewline-eof -Wnullable-to-nonnull-conversion -Wobjc-interface-ivars -Wover-aligned -Wpacked -Wpointer-arith -Wselector -Wshadow -Wshorten-64-to-32 -Wsign-conversion -Wstatic-in-inline -Wsuper-class-method-mismatch -Wswitch -Wunguarded-availability -Wunreachable-code -Wunused -Wno-unknown-warning-option -Wno-trigraphs -Wno-four-char-constants -Wno-disabled-macro-expansion -Wno-pedantic -Wno-bad-function-cast -Wno-c++-compat -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-cast-align -Wno-cast-qual -Wno-documentation-unknown-command -Wno-format-nonliteral -Wno-missing-variable-declarations -Wno-old-style-cast -Wno-padded -Wno-reserved-id-macro -Wno-shift-sign-overflow -Wno-undef -Wno-unreachable-code-aggressive -Wno-unused-macros -Wno-used-but-marked-unused -Wno-void-pointer-to-int-cast -Wno-vla -Wno-error=assign-enum -fmodule-map-file=/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/dispatch/generic/module.modulemap -fmodule-map-file=/home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/private/generic/module.modulemap -fno-exceptions -fblocks -momit-leaf-frame-pointer -MD -MT src/CMakeFiles/dispatch.dir/apply.c.o -MF src/CMakeFiles/dispatch.dir/apply.c.o.d -o src/CMakeFiles/dispatch.dir/apply.c.o -c /home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/src/apply.c
[   19s] /home/abuild/rpmbuild/BUILD/swift-corelibs-libdispatch-swift-5.10.1-RELEASE/src/apply.c:366:4: error: cast from 'dispatch_function_t' (aka 'void (*)(void * _Nullable)') to 'dispatch_apply_function_t' (aka 'void (*)(void *, unsigned long)') converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
[   19s]   366 |                         (dispatch_apply_function_t)_dispatch_Block_invoke(work));
[   19s]       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[   19s] 1 error generated.

[xuzhen]

Wrote a patch to ignore that error

--- a/cmake/modules/DispatchCompilerWarnings.cmake	2024-12-21 23:02:06.831097446 +0800
+++ b/cmake/modules/DispatchCompilerWarnings.cmake	2024-12-21 23:01:41.086280651 +0800
@@ -50,6 +50,7 @@
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-disabled-macro-expansion>)
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-pedantic>)
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-bad-function-cast>)
+  add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-cast-function-type-mismatch>)
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-c++-compat>)
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-c++98-compat>)
   add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-Wno-c++98-compat-pedantic>)