https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111527
Bug ID: 111527
Summary: COLLECT_GCC_OPTIONS option hits single-variable limits
too early
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: driver
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
Tl;DR:
linux allows you to pass up to 2MB of command line arguments to the tools
limiting each individual option to 128KB. Unfortunately `gcc` collects all the
options into a single `COLLECT_GCC_OPTIONS` variable and hits the smaller 128KB
limit.
This causes periodic problems for distributions that install each individual
package into a separate directory. One of them is `NixOS`.
Could `gcc` be amended not to use single limiting `COLLECT_GCC_OPTIONS`
variable and use, say, direct arguments to pass options around? Or even use
response file if it hits `-E2BIG`?
Fake reproducer: 2 huge variables that programs normally accept, but not
`gcc`:
$ big_100k_var=$(printf "%0*d" 100000 0)
# this works: 200KB of options for `printf` external command
$ $(which printf) "%s %s" $big_100k_var $big_100k_var >/dev/null; echo $?
0
# this fails: 200KB of options for `gcc`, fails in `cc1`
$ touch a.c; gcc -c a.c -DA=$big_100k_var -DB=$big_100k_var
gcc: fatal error: cannot execute 'cc1': execv: Argument list too long
compilation terminated.
Thanks!
MOre words
In `nixpkgs` repository each package gets installed into it's own unique
directory:
/nix/store/hash1-foo/include/foo.h
/nix/store/hash2-bar/include/bar.h
...
If any of those encounter `__FILE__` macros in static inline functions they
usually embed full path to header files into final binaries as is.
I wanted to remap all those paths into form that does not contain hashes:
-fmacro-prefix-map=/nix/store/hash1-foo/include/foo.h=/nix/store/00000000-foo/include/foo.h
-fmacro-prefix-map=/nix/store/hash2-bar/include/bar.h=/nix/store/00000000-bar/include/bar.h
...
When I got to packages that use about ~100 include directories I started
getting errors from `cc1`:
```
Command line: `gcc -m64 -mcx16 $remap_options
/build/qemu-8.1.0/build/meson-private/tmpbyikv8nc/testfile.c \
-o /build/qemu-8.1.0/build/meson-private/tmpbyikv8nc/output.exe
-D_FILE_OFFSET_BITS=64 \
-O0 -Wl,--start-group -laio -Wl,--end-group -Wl,--allow-shlib-undefined` -> 1
stderr:
gcc: fatal error: cannot execute 'cc1': execv: Argument list too long
compilation terminated.
```
The limit felt too low and I found the `COLLECT_GCC_OPTIONS` variable.
