Hi Camm, The Fedora project is currently rebuilding all packages with what will soon be GCC 10. I have encountered two issues so far and thought I should give you a heads up.
GCC has long defaulted to -fcommon, but GCC 10 flips the default to -fno-common. As a result, the link step fails with complaints about lots of multiply-defined variables. A quick workaround is to add -fcommon to the build flags. Otherwise, the code would have to be altered to ensure that there is exactly one compilation unit containing a definition for each variable. After adding -fcommon, the build still fails like this: COMPILER> Error: ERROR "Caught fatal error [memory may be damaged]" Signalled by EQUAL-TAIL-RECURSION-CHECK. ERROR "Caught fatal error [memory may be damaged]" Broken at SYSTEM::DO-BREAK-LEVEL. Type :H for Help. 1 Return to top level. COMPILER>>2148155904 heap words available NIL COMPILER>> NIL COMPILER>>make[1]: *** [makefile:98: saved_pre_gcl] Error 255 Here is a disassembly of cclear_stack on an x86_64 machine: 0000000000005370 <cclear_stack>: 5370: f3 0f 1e fa endbr64 5374: 31 c0 xor %eax,%eax 5376: c3 retq GCC 10 has concluded that it can optimize cclear_stack away, as that simply returns 0. GCC may feel it is justified in doing so because of this warning: main.c: In function 'cclear_stack': main.c:454:10: warning: function returns address of local variable [ ]8;;https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wreturn-local-addr -Wreturn-local-addr ]8;; ] 454 | return v; | ^ In file included from /usr/include/stdlib.h:568, from main.c:27: main.c:452:11: note: declared here 452 | void *v=alloca(size); | ^~~~~~ The same thing has happened with gcl_strncpy_chk; it just returns 0. What are these functions supposed to do? EQUAL-TAIL-RECURSION-CHECK in particular, even if cclear_stack is not optimized away, touches memory it isn't allowed to touch, memory belonging to a stack frame that has been popped. A conforming compiler is allowed to generate code that segfaults (precisely what GCC 10 is doing). I should also mention this output from the configure script: checking finding default linker script... gawk: cmd. line:1: warning: regexp escape sequence `\=' is not a known regexp operator got it Perhaps all of the "\=" should be "\\="? Regards, -- Jerry James http://www.jamezone.org/