Fix spkg-configure.m4 for singular

[mkoeppe]

Follow-up from #29024. This time with testing on more than 1 platform.

On Debian 11 (a.k.a. bullseye, stable) Singular's libs have different names, and are failing to be picked up: they all are installed in /usr/lib/x86_64-linux-gnu/ and we have the following: I add Sage's names next to their

Debian                             Sage

libsingular-factory.so             libfactory.so
libsingular-gfan.so                ???
libsingular-omalloc.so             libomalloc.so
libsingular-polys.so               libpolys.so
libsingular-resources.so           libsingular_resources.so
libsingular-Singular.so            libSingular.so            

While it's not hard to test for libsingular-Singular.so in place of libSingular.so, it's some more work to use it.

Library names may be obtained from $ pkg-config --libs-only-l singular, which on Debian produces

-lsingular-Singular -ldl -lsingular-polys -lntl -lgmp -ldl -lsingular-factory -lntl -lgmp -lsingular-omalloc -lsingular-resources

Upstream: Reported upstream. No feedback yet.

CC: @dimpase @kiwifb @slel @isuruf @orlitzky @tobiasdiez @tobihan

Component: build: configure

Author: Dima Pasechnik

Branch/Commit: c0ceaf5

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32789

[dimpase]

Description changed:

--- 
+++ 
@@ -1,2 +1,23 @@
 Follow-up from #29024. This time with testing on more than 1 platform.
 
+On Debian 11 (a.k.a. bullseye, stable) Singular's libs have different names, and are failing to be picked up: they all are installed in `/usr/lib/x86_64-linux-gnu/` and we have the following: I add Sage's names next to their
+
+```
+Debian                             Sage
+
+libsingular-factory.so             libfactory.so
+libsingular-gfan.so                ???
+libsingular-omalloc.so             libomalloc.so
+libsingular-polys.so               libpolys.so
+libsingular-resources.so           libsingular_resources.so
+libsingular-Singular.so            libSingular.so            
+```
+
+While it's not hard to test for `libsingular-Singular.so` in place of `libSingular.so`, it's some more work to use it.
+
+Library names may be obtained from `$ pkg-config --libs-only-l singular`, which on Debian produces
+
+```
+-lsingular-Singular -ldl -lsingular-polys -lntl -lgmp -ldl -lsingular-factory -lntl -lgmp -lsingular-omalloc -lsingular-resources
+```
+

[mkoeppe]

Description changed:

--- 
+++ 
@@ -21,3 +21,15 @@
 -lsingular-Singular -ldl -lsingular-polys -lntl -lgmp -ldl -lsingular-factory -lntl -lgmp -lsingular-omalloc -lsingular-resources
 ```
 
+
+Also broken on Cygwin, as reported in https://groups.google.com/g/sage-release/c/FXpakLURP_0/m/La20cB4rBgAJ:
+
+```
+  [sagemath_doc_html-none]     File "sage/libs/singular/singular.pyx", line 1555, in init sage.libs.singular.singular (build/cythonized/sage/libs/singular/singular.cpp:15622)
+  [sagemath_doc_html-none]     File "sage/libs/singular/singular.pyx", line 1530, in sage.libs.singular.singular.init_libsingular (build/cythonized/sage/libs/singular/singular.cpp:12925)
+  [sagemath_doc_html-none]   ImportError: cannot load Singular library from /home/s/sage9n/local/bin/libSingular.dll (b'No such file or directory')
+  [sagemath_doc_html-none]   Error: './sage --docbuild --all-documents' failed
+```
+
+
+

[mkoeppe]

Description changed:

--- 
+++ 
@@ -22,7 +22,7 @@
 ```
 
 
-Also broken on Cygwin, as reported in https://groups.google.com/g/sage-release/c/FXpakLURP_0/m/La20cB4rBgAJ:
+Also broken on Cygwin (with singular from SPKG, as the cygwin-provided Singular is too old and is correctly rejected), as reported in https://groups.google.com/g/sage-release/c/FXpakLURP_0/m/La20cB4rBgAJ:
 
 ```
   [sagemath_doc_html-none]     File "sage/libs/singular/singular.pyx", line 1555, in init sage.libs.singular.singular (build/cythonized/sage/libs/singular/singular.cpp:15622)

[orlitzky]

comment:4

We already tried to fix the path to libSingular on cygwin once. Where does it really live?

[mkoeppe]

comment:5

We have a GH Actions workflow for Cygwin that allows you to download logs and the installation in SAGE_LOCAL for inspection, see for example https://github.com/sagemath/sage/actions/runs/1478855916

[slel]

comment:6

Happy to run any commands under Cygwin too.

[mkoeppe]

comment:7

From https://github.com/mkoeppe/sage/suites/4487559073/artifacts/119913634:
The following DLLs are installed in SAGE_LOCAL/bin:

cygfactory-4-2-1.dll
cygomalloc-0-9-6.dll
cygpolys-4-2-1.dll
cygsingular_resources-4-2-1.dll
cygSingular-4-2-1.dll

[orlitzky]

comment:8

Replying to @mkoeppe:

cygSingular-4-2-1.dll

Is there a symlink from cygSingular.dll to that file?

[mkoeppe]

comment:9

No

[mkoeppe]

comment:10

There is also a file SAGE_LOCAL/lib/libSingular.dll.a, which is used by the linker, and probably contains the information about the name of the actual DLL somehow.

[mkoeppe]

comment:11

Apparently https://sourceware.org/binutils/docs/binutils/dlltool.html can be used for reading this info.

@slel, could you run dlltool --identify local/lib/libSingular.dll.a please?

[orlitzky]

comment:12

The SPKG won't be installed yet, so we can't read local/lib/libSingular.dll.a to obtain the necessary path during ./configure. For the SPKG, we could hard-code the value as a last resort. Their library versioning scheme also corresponds to package-version.txt, but I doubt that's reliable.

Detecting the system copy should be relatively easy in comparison. Unless there's a way to install multiple copies into the system libdir, we can use find to pick out what is hopefully the only copy of cygSingular*.dll during ./configure.

[mkoeppe]

comment:13

It would probably be a good idea to first test whether this whole symbol visibility issue is even a thing on Cygwin.

[mkoeppe]

Branch: u/mkoeppe/fix_spkg_configure_m4_for_singular

[mkoeppe]

Dependencies: #32944, #32945