Better Backtrace on i686 on the crash:

(gdb) bt
#0  0xf7fd4b59 in __kernel_vsyscall ()
#1  0xf7defa60 in raise () from /gnu/store/qk8irm5yp2khq4dj7zcpcaa1g87pfyvw-glibc-2.28/lib/libc.so.6
#2  0xf7df0bd7 in abort () from /gnu/store/qk8irm5yp2khq4dj7zcpcaa1g87pfyvw-glibc-2.28/lib/libc.so.6
#3  0xf7e2ff56 in __libc_message () from /gnu/store/qk8irm5yp2khq4dj7zcpcaa1g87pfyvw-glibc-2.28/lib/libc.so.6
#4  0xf7e36bbd in malloc_printerr () from /gnu/store/qk8irm5yp2khq4dj7zcpcaa1g87pfyvw-glibc-2.28/lib/libc.so.6
#5  0xf7e3713b in munmap_chunk () from /gnu/store/qk8irm5yp2khq4dj7zcpcaa1g87pfyvw-glibc-2.28/lib/libc.so.6
#6  0x0804e63e in _ZRK$aL_ZN5alloc7raw_vec6RawVec$aLu8$aR_as__ZN4core3ops4Drop$aR4drop (arg0=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:61640
#7  _ZRI$aL_ZN5alloc7raw_vec6RawVec$aLu8$aR$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:175
#8  _ZRI$aL_ZN11collections3vec3Vec$aLu8$aR$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:185
#9  _ZRI$aL_ZN11collections6string6String$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:192
#10 _ZRI$aL_ZN12syn$$0_11_115ident5Ident$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:199
#11 _ZRI$aL_ZN4core6option12Option$HSome$aL_ZN12syn$$0_11_115ident5Ident$aR$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:2304
#12 _ZRI$aL_ZN4core6option6Option$aL_ZN12syn$$0_11_115ident5Ident$aR$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:2313
#13 _ZRI$aL_ZN30serde_derive_internals$$0_15_03ast5Field$aR11$Hdrop_glue (rv=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:2350
#14 _ZRK$aL_ZN11collections3vec3Vec$aL_ZN30serde_derive_internals$$0_15_03ast5Field$aR_as__ZN4core3ops4Drop$aR4drop (arg0=0xffffc47c, arg0@entry=0xffffc558) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:64862
#15 _ZRI$aL_ZN11collections3vec3Vec$aL_ZN30serde_derive_internals$$0_15_03ast5Field$aR$aR11$Hdrop_glue (rv=rv@entry=0xffffc47c) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:1843
#16 0x0804e758 in _ZRI$aL_ZN30serde_derive_internals$$0_15_03ast12Body$HStruct$aR11$Hdrop_glue (rv=0xffffc478) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:1852
#17 _ZRI$aL_ZN30serde_derive_internals$$0_15_03ast4Body$aR11$Hdrop_glue (rv=0xffffc478) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:1868
#18 _ZRI$aL_ZN30serde_derive_internals$$0_15_03ast9Container$aR11$Hdrop_glue (rv=rv@entry=0xffffc3a0) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:1882
#19 0x08070393 in _ZN19serde_derive$$1_0_62de25expand_derive_deserialize (arg0=0xffffc57c) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:34299
#20 0x080708a1 in _ZN19serde_derive$$1_0_618derive_deserialize (arg0=...) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:35190
#21 0x080eeb83 in _ZN10proc_macro4main (arg0=...) at output/libproc_macro.hir.o.c:5239
#22 0x0804b114 in _ZN19serde_derive$$1_0_612proc_macro$H4main () at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:35286
#23 0x080eb1fb in __rust_maybe_catch_panic (arg0=0x80bcb20 <_ZN3std9panicking3$H37do_call$aLfn_0_$T0$C$T0$aR>, arg1=0xffffc7b4 "", arg2=0xffffc7ac, arg3=0xffffc7b0) at output/libpanic_abort.hir.o.c:142
#24 0x080d052a in _ZN3std9panicking3try$aL$T0$Cfn_0_$T0$aR (arg0=0x804b100 <_ZN19serde_derive$$1_0_612proc_macro$H4main>) at output/libstd.hir.o.c:63801
#25 0x080d44f3 in _ZN3std2rt10lang_start (arg0=0x804b100 <_ZN19serde_derive$$1_0_612proc_macro$H4main>, arg1=2, arg2=0xffffc904) at output/libstd.hir.o.c:64578
#26 0x08049bc0 in main (argc=2, argv=0xffffc904) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:86165
(gdb) frame 6
#6  0x0804e63e in _ZRK$aL_ZN5alloc7raw_vec6RawVec$aLu8$aR_as__ZN4core3ops4Drop$aR4drop (arg0=0x815c300) at output/cargo-build/libserde_derive-1_0_6.hir-plugin.c:61640
61640           _ZN5alloc4heap17__rust_deallocate( var4, var0, 0x1ull );
(gdb) l
61635   bb1:
61636           var0 = var0 * arg0->_1; // Local(0) = BinOp(Local(0) MUL Field(1, Deref(Argument(0))))
61637           var3 = arg0;    // Local(3) = Borrow(0, Shared, Deref(Argument(0)))
61638           var4 = (uint8_t *)var3->_0._0._0;       // Local(4) = Cast(Field(0, Field(0, Field(0, Deref(Local(3))))) as *mut u8)
61639           var4 = var4;    // Local(4) = Cast(Local(4) as *mut u8)
61640   !!      _ZN5alloc4heap17__rust_deallocate( var4, var0, 0x1ull );
61641           // ^ Call( Local(2) = ::"alloc"::heap::__rust_deallocate( Local(4), Local(0), 1 usize, ), bb2, bb3)
61642   bb2:
61643           ;       // Local(2) = Tuple()
61644           rv = var2;      // Return = Use(Local(2))

Compiler output file is attached.