’ declared here
struct pair
^~~~
Makefile:144: recipe for target 'codegen.o' failed
make[1]: *** [codegen.o] Error 1
Makefile:94: recipe for target 'julia-src-release' failed
make: *** [julia-src-release] Error 2
```
---
### Author:  [@Keno](https://discourse.julialang.org/u/Keno)
#### Post date: [May 31, 2018, 12:17am UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/2 "2018-05-31T00:17:59Z")
Try removing one of the extra pairs of parentheses after the `&`. I don’t have the C standard in front of me, but I imagine that that might turn an lvalue into an rvalue.
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [May 31, 2018, 6:21am UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/3 "2018-05-31T06:21:12Z")
No luck. Removing the outer most parenthesis results in the same error, while removing those around `rts_var`:
```nohighlight
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
```
results in that error appearing in many places throughout the build:
```julia
CC src/jloptions.o
In file included from /home/chris/Documents/prog/julia/src/jltypes.c:14:
/home/chris/Documents/prog/julia/src/jltypes.c: In function ‘jl_type_union’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jltypes.c:405:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(temp, nt+1);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jltypes.c: In function ‘jl_apply_type2’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jltypes.c:836:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(args, 2);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jltypes.c: In function ‘check_datatype_parameters’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jltypes.c:953:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(bounds, np*2);
^ ~~~~~~~~~~~~~
In file included from /home/chris/Documents/prog/julia/src/gf.c:14:
/home/chris/Documents/prog/julia/src/gf.c: In function ‘jl_type_infer’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/gf.c:247:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(fargs, 3);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jltypes.c: In function ‘inst_tuple_w_’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jltypes.c:1317:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(iparams, onstack ? ntp : 1);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jltypes.c: In function ‘inst_type_w_’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jltypes.c:1417:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(iparams, ntp);
^ ~~~~~~~~~~~~~
In file included from /home/chris/Documents/prog/julia/src/builtins.c:24:
/home/chris/Documents/prog/julia/src/builtins.c: In function ‘jl_f__apply’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/builtins.c:372:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(newargs, onstack ? n : 1);
^ ~~~~~~~~~~~~~
In file included from /home/chris/Documents/prog/julia/src/jlapi.c:14:
/home/chris/Documents/prog/julia/src/jlapi.c: In function ‘jl_call’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jlapi.c:140:9: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, nargs+1);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jlapi.c: In function ‘jl_call1’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jlapi.c:180:9: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, 2);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/gf.c: In function ‘arg_type_tuple’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/gf.c:1499:9: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(types, nargs);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jlapi.c: In function ‘jl_call2’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jlapi.c:200:9: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, 3);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/jlapi.c: In function ‘jl_call3’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/jlapi.c:221:9: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, 4);
^ ~~~~~~~~~~~~~
In file included from /home/chris/Documents/prog/julia/src/precompile.c:11:
/home/chris/Documents/prog/julia/src/precompile.c: In function ‘_compile_all_tvar_union’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/precompile.c:111:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(env, 2 * tvarslen);
^ ~~~~~~~~~~~~~
In file included from /home/chris/Documents/prog/julia/src/interpreter.c:9:
/home/chris/Documents/prog/julia/src/interpreter.c: In function ‘do_call’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/interpreter.c:71:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, nargs);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/interpreter.c: In function ‘do_invoke’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/interpreter.c:83:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(argv, nargs - 1);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/sys.c: In function ‘jl_readuntil’:
/home/chris/Documents/prog/julia/src/sys.c:284:17: warning: unused variable ‘truncret’ [-Wunused-variable]
int truncret = ios_trunc(&dest, n); // it should always be possible to truncate dest
^ ~~~~~~~
Makefile:140: recipe for target 'jlapi.o' failed
make[1]: *** [jlapi.o] Error 1
make[1]: *** Waiting for unfinished jobs....
/home/chris/Documents/prog/julia/src/interpreter.c: In function ‘jl_interpret_call’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/interpreter.c:659:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(locals, jl_source_nslots(src) + jl_source_nssavalues(src) + 2);
^ ~~~~~~~~~~~~~
/home/chris/Documents/prog/julia/src/interpreter.c: In function ‘jl_interpret_toplevel_thunk’:
/home/chris/Documents/prog/julia/src/julia.h:627:32: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var[-2])
^
/home/chris/Documents/prog/julia/src/interpreter.c:685:5: note: in expansion of macro ‘JL_GC_PUSHARGS’
JL_GC_PUSHARGS(locals, jl_source_nslots(src) + jl_source_nssavalues(src));
^ ~~~~~~~~~~~~~
Makefile:140: recipe for target 'precompile.o' failed
make[1]: *** [precompile.o] Error 1
Makefile:140: recipe for target 'jltypes.o' failed
make[1]: *** [jltypes.o] Error 1
Makefile:140: recipe for target 'gf.o' failed
make[1]: *** [gf.o] Error 1
Makefile:140: recipe for target 'interpreter.o' failed
make[1]: *** [interpreter.o] Error 1
Makefile:140: recipe for target 'builtins.o' failed
make[1]: *** [builtins.o] Error 1
Makefile:94: recipe for target 'julia-src-release' failed
make: *** [julia-src-release] Error 2
```
Implying that the line as it currently is:
```julia
jl_pgcstack = (jl_gcframe_t*)&(((void**)rts_var)[-2])
```
is fine in for all those files, but something goes wrong while trying to build codegen.
EDIT:
I did just confirm that it does still build with gcc 8.1.0. I am only having issues with gcc 9.0.0.
---
### Author:  [@yuyichao](https://discourse.julialang.org/u/yuyichao)
#### Post date: [May 31, 2018, 11:19am UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/4 "2018-05-31T11:19:59Z")
Remove the inner most cast
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [May 31, 2018, 11:44am UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/5 "2018-05-31T11:44:51Z")
That worked:
```julia
#define JL_GC_PUSHARGS(rts_var,n) \
rts_var = ((jl_value_t**)alloca(((n)+2)*sizeof(jl_value_t*)))+2; \
((void**)rts_var)[-2] = (void*)(((size_t)(n))<<1); \
((void**)rts_var)[-1] = jl_pgcstack; \
memset((void*)rts_var, 0, (n)*sizeof(jl_value_t*)); \
jl_pgcstack = (jl_gcframe_t*)&((rts_var)[-2])
// jl_pgcstack = (jl_gcframe_t*)&(((void**)rts_var)[-2])
```
What does casting to `void**` do – and what are the consequences of removing it?
---
### Author:  [@yuyichao](https://discourse.julialang.org/u/yuyichao)
#### Post date: [May 31, 2018, 11:57am UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/6 "2018-05-31T11:57:55Z")
> [@Elrod](#):
>
> jl\_pgcstack = (jl\_gcframe\_t\*)&((rts\_var)[-2])
If you don’t want to change any requirement on the caller, you can use.
`jl_pgcstack = (jl_gcframe_t*)((void**)(rts_var) - 2)`
(Or `void***` if you want to code to be exactly the same as before…)
---
### Author:  [@Keno](https://discourse.julialang.org/u/Keno)
#### Post date: [May 31, 2018, 12:15pm UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/7 "2018-05-31T12:15:28Z")
> [@Elrod](#):
>
> jl\_pgcstack = (jl\_gcframe\_t\*)&((void\*\*)rts\_var[-2])
That’s not the one I meant. I meant:
```julia
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var)[-2]
```
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [May 31, 2018, 1:10pm UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/8 "2018-05-31T13:10:10Z")
Sorry I wasn’t clear – I did try that first, but it resulted in the same error as I had earlier:
```julia
/home/chris/Documents/prog/julia-reg/src/julia.h:696:55: error: lvalue required as unary ‘&’ operand
jl_pgcstack = (jl_gcframe_t*)&((void**)rts_var)[-2]
^
```
So out of curiosity I tried what I showed that post (removing parenthesis around `rts_var`), and that time got the error in many different places, much earlier.
Yuyichao – I assume it is better not to change requirements? That suggestion also worked without issue:
```julia
jl_pgcstack = (jl_gcframe_t*)((void**)(rts_var) - 2)
```
---
### Author:  [@Keno](https://discourse.julialang.org/u/Keno)
#### Post date: [May 31, 2018, 1:11pm UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/9 "2018-05-31T13:11:33Z")
> [@Elrod](#):
>
> Sorry I wasn’t clear – I did try that first, but it resulted in the same error as I had earlier:
In that case, that sounds like a gcc bug to me. The C standard is fairly clear that a `&` and `[]` need to semantically cancel.
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [June 1, 2018, 3:41pm UTC](https://discourse.julialang.org/t/error-building-julia-bug-in-latest-gcc-9-0-0-experimental-or-in-julias-gc-code/11253/10 "2018-06-01T15:41:51Z")
Okay – think I should say something on their mailing list?