GC failure when compiling Maxima

[Marius Gerbershagen]

Compiling Maxima (both the last release 5.46.0 and the current master branch from the git repository) with sbcl on a linux x86_64 platform leads to a garbage collector failure in the step where maxima tries to dump the image:

```
; - Providing system maxima
pre-GC failure
Ptr 0x10047c469f @ 10059bad78 (lispobj 10059bad7f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bad98 (lispobj 10059bad9f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bada8 (lispobj 10059badaf,pg2871) sees junk
Ptr 0x10047c469f @ 10059badd8 (lispobj 10059baddf,pg2871) sees junk
Ptr 0x10047c469f @ 10059bade8 (lispobj 10059badef,pg2871) sees junk
Ptr 0x10047c469f @ 10059badf8 (lispobj 10059badff,pg2871) sees junk
Ptr 0x10047c469f @ 10059bae28 (lispobj 10059bae2f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bae38 (lispobj 10059bae3f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bae58 (lispobj 10059bae5f,pg2871) sees junk
Ptr 0x10047c469f @ 10059baeb8 (lispobj 10059baebf,pg2871) sees junk
Ptr 0x10047c469f @ 10059baf18 (lispobj 10059baf1f,pg2871) sees junk
Ptr 0x10047c469f @ 10059baf48 (lispobj 10059baf4f,pg2871) sees junk
Ptr 0x10047c469f @ 10059baf58 (lispobj 10059baf5f,pg2871) sees junk
Ptr 0x10047c469f @ 10059baf88 (lispobj 10059baf8f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bafd8 (lispobj 10059bafdf,pg2871) sees junk
Ptr 0x10047c469f @ 10059bafe8 (lispobj 10059bafef,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb038 (lispobj 10059bb03f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb048 (lispobj 10059bb04f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb078 (lispobj 10059bb07f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb088 (lispobj 10059bb08f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb098 (lispobj 10059bb09f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb0c8 (lispobj 10059bb0cf,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb0f8 (lispobj 10059bb0ff,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb108 (lispobj 10059bb10f,pg2871) sees junk
Ptr 0x10047c469f @ 10059bb138 (lispobj 10059bb13f,pg2871) sees junk
fatal error encountered in SBCL pid 172610 tid 172610:
Verify failed: 26 errors

Welcome to LDB, a low-level debugger for the Lisp runtime environment.
(GC in progress, oldspace=-1, newspace=-1)
ldb>
```

I have traced this down to sbcl commit 609a19bb3cf526f01b072c0a132afb34e1b7cf24 using git bisect. Is this a GC bug in sbcl or could this possibly be caused by Maxima modifying literal data (which I have noticed sbcl recently puts into read-only memory)?

[Douglas Katzman (dougk)]

fixed by https://sourceforge.net/p/sbcl/sbcl/ci/48d686f9

thanks for the report