The problem was observed with the Arm Embedded GCC toolchain gcc-arm-none-eabi-8-2018-q4-major; the previous Arm release gcc-arm-none-eabi-7-2017-q4-major seems ok, so the bug was introduced in this interval.


While investigating, I used two projects (both in the attached archive). 

The initial project (f4b-lto) was created by the GNU MCU Eclipse STM32F4 blinky template.

The f4b-lto/Debug/f4b-lto.elf crashes GDB early while loding the symbols:

$ /Users/ilg/opt/gcc-arm-none-eabi-8-2018-q4-major/bin/arm-none-eabi-gdb /Users/ilg/Desktop/eclipse-workspace-2018-12/f4b-lto/Debug/f4b-lto.elf 
GNU gdb (GNU Tools for Arm Embedded Processors 8-2018-q4-major) 8.2.50.20181213-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-apple-darwin10 --target=arm-none-eabi".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
/Users/ilg/.gdbinit:1: Error in sourced command file:
No symbol table is loaded.  Use the "file" command.
Reading symbols from /Users/ilg/Desktop/eclipse-workspace-2018-12/f4b-lto/Debug/f4b-lto.elf...
Segmentation fault: 11
ilg-mbp:~ ilg$ 


The second project (f4b-lto-test) was a progressive simplification of the first, until it no longer crashed GDB. 

Unfortunately it still did not work, it trew an assert while GDB was trying to start the GDB debug session:


551,953 &"symbol-file /Users/ilg/Desktop/eclipse-workspace-2018-12/f4b-lto-test/Debug/f4b-lto-test.e\
 lf\n"
 551,953 ~"Reading symbols from /Users/ilg/Desktop/eclipse-workspace-2018-12/f4b-lto-test/Debug/f4b-l\
 to-test.elf...\n"
 551,962 30^done
 551,962 (gdb) 
 551,964 &"load /Users/ilg/Desktop/eclipse-workspace-2018-12/f4b-lto-test/Debug/f4b-lto-test.elf\n"
 551,964 ~"Loading section .isr_vector, size 0x3bc lma 0x8000000\n"
 551,966 31+download,{section=".isr_vector",section-size="956",total-size="934014"}
 551,966 31+download,{section=".isr_vector",section-sent="956",section-size="956",total-sent="956",to\
 tal-size="934014"}
 551,966 ~"Loading section .inits, size 0x28 lma 0x80003bc\n"
 551,968 31+download,{section=".inits",section-size="40",total-size="934014"}
 551,968 ~"Loading section .text, size 0xcf3 lma 0x80003f0\n"
 551,968 31+download,{section=".text",section-size="3315",total-size="934014"}
 551,968 ~"Loading section .data, size 0x74 lma 0x80010e4\n"
 551,969 31+download,{section=".data",section-size="116",total-size="934014"}
 551,969 ~"Start address 0x80002a4, load size 4427\n"
 552,406 ~"Transfer rate: 864 KB/sec, 1106 bytes/write.\n"

 552,407 ~"/tmp/jenkins-GCC-8-build-toolchain-mac_cluster-128_20181216_1544945247/src/gdb/gdb/dwarf2r\
 ead.c:9809: internal-error: void dw2_add_symbol_to_list(struct symbol *, struct pending **): Asserti\
 on `(*listhead) == NULL || (SYMBOL_LANGUAGE ((*listhead)->symbol[0]) == SYMBOL_LANGUAGE (symbol))' f\
 ailed.\nA problem internal to GDB has been detected,\nfurther debugging may prove unreliable.\nQuit \
 this debugging session? "
 552,408 ~"(y or n) [answered Y; input not from terminal]\n"
 552,408 &"\nThis is a bug, please report it."
 552,408 &"  For instructions, see:\n<http://www.gnu.org/software/gdb/bugs/>."
 552,408 &"\n\n"
 552,408 ~"/tmp/jenkins-GCC-8-build-toolchain-mac_cluster-128_20181216_1544945247/src/gdb/gdb/dwarf2r\
 ead.c:9809: internal-error: void dw2_add_symbol_to_list(struct symbol *, struct pending **): Asserti\
 on `(*listhead) == NULL || (SYMBOL_LANGUAGE ((*listhead)->symbol[0]) == SYMBOL_LANGUAGE (symbol))' f\
 ailed.\nA problem internal to GDB has been detected,\nfurther debugging may prove unreliable.\nCreat\
 e a core file of GDB? "
 552,409 ~"(y or n) [answered Y; input not from terminal]\n"



In both cases the project was compiled with -Og.

To identify if the problem is in the compiler vs the debugger, I tried to debug the executable created by GCC 8 with the debugger from the GCC 7 distribution and it was ok, so this is the reason why I suspected GDB.