Failure to install in Debian trixie: #error libgit2 version is not compatible

Updating the Docker image we use from bullseye-slim to newly released trixie-slim, rugged is failing to install.

The installation log

checking for gmake... -------------------- yes



--------------------



pkg_config: checking for pkg-config for libgit2... -------------------- [" ", "", "-lgit2"]



LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 pkg-config --exists libgit2

LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 pkg-config --libs libgit2 |

=> "-lgit2 \n"

LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 "gcc -o conftest -I/usr/local/include/ruby-3.4.0/x86_64-linux -I/usr/local/include/ruby-3.4.0/ruby/backward -I/usr/local/include/ruby-3.4.0 -I.    -fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2  -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wdeprecated-declarations -Wdiv-by-zero -Wduplicated-cond -Wimplicit-function-declaration -Wimplicit-int -Wpointer-arith -Wwrite-strings -Wold-style-definition -Wimplicit-fallthrough=0 -Wmissing-noreturn -Wno-cast-function-type -Wno-constant-logical-operand -Wno-long-long -Wno-missing-field-initializers -Wno-overlength-strings -Wno-packed-bitfield-compat -Wno-parentheses-equality -Wno-self-assign -Wno-tautological-compare -Wno-unused-parameter -Wno-unused-value -Wsuggest-attribute=format -Wsuggest-attribute=noreturn -Wunused-variable -Wmisleading-indentation -Wundef  -fPIC  -g -O3 -Wall -Wno-comment conftest.c -L. -L/usr/local/lib -Wl,-rpath,/usr/local/lib -L. -fstack-protector-strong -rdynamic -Wl,-export-dynamic -Wl,--no-as-needed     -Wl,-rpath,/usr/local/lib -L/usr/local/lib -lruby  -lm -lpthread  -lc"

checked program was:

/* begin */

1: #include "ruby.h"

2: 

3: int main(int argc, char **argv)

4: {

5:   return !!argv[argc];

6: }

/* end */



LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 "gcc -o conftest -I/usr/local/include/ruby-3.4.0/x86_64-linux -I/usr/local/include/ruby-3.4.0/ruby/backward -I/usr/local/include/ruby-3.4.0 -I.    -fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2  -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wdeprecated-declarations -Wdiv-by-zero -Wduplicated-cond -Wimplicit-function-declaration -Wimplicit-int -Wpointer-arith -Wwrite-strings -Wold-style-definition -Wimplicit-fallthrough=0 -Wmissing-noreturn -Wno-cast-function-type -Wno-constant-logical-operand -Wno-long-long -Wno-missing-field-initializers -Wno-overlength-strings -Wno-packed-bitfield-compat -Wno-parentheses-equality -Wno-self-assign -Wno-tautological-compare -Wno-unused-parameter -Wno-unused-value -Wsuggest-attribute=format -Wsuggest-attribute=noreturn -Wunused-variable -Wmisleading-indentation -Wundef  -fPIC  -g -O3 -Wall -Wno-comment conftest.c -L. -L/usr/local/lib -Wl,-rpath,/usr/local/lib -L. -fstack-protector-strong -rdynamic -Wl,-export-dynamic -Wl,--no-as-needed -lgit2    -Wl,-rpath,/usr/local/lib -L/usr/local/lib -lruby  -lm -lpthread  -lc"

checked program was:

/* begin */

1: #include "ruby.h"

2: 

3: int main(int argc, char **argv)

4: {

5:   return !!argv[argc];

6: }

/* end */



LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 pkg-config --cflags-only-I libgit2 |

=> "\n"

LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 pkg-config --cflags-only-other libgit2 |

=> "\n"

LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 pkg-config --libs-only-l libgit2 |

=> "-lgit2 \n"

package configuration for libgit2

incflags: 

cflags: 

ldflags: 

libs: -lgit2



--------------------



LD_LIBRARY_PATH=.:/usr/local/lib ASAN_OPTIONS=detect_leaks=0 "gcc -I/usr/local/include/ruby-3.4.0/x86_64-linux -I/usr/local/include/ruby-3.4.0/ruby/backward -I/usr/local/include/ruby-3.4.0 -I.     -fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2  -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wdeprecated-declarations -Wdiv-by-zero -Wduplicated-cond -Wimplicit-function-declaration -Wimplicit-int -Wpointer-arith -Wwrite-strings -Wold-style-definition -Wimplicit-fallthrough=0 -Wmissing-noreturn -Wno-cast-function-type -Wno-constant-logical-operand -Wno-long-long -Wno-missing-field-initializers -Wno-overlength-strings -Wno-packed-bitfield-compat -Wno-parentheses-equality -Wno-self-assign -Wno-tautological-compare -Wno-unused-parameter -Wno-unused-value -Wsuggest-attribute=format -Wsuggest-attribute=noreturn -Wunused-variable -Wmisleading-indentation -Wundef  -fPIC  -g -O3 -Wall -Wno-comment    -c conftest.c"

In file included from conftest.c:3:

/usr/include/git2/version.h:16:1: error: unknown type name ‘GIT_BEGIN_DECL’

   16 | GIT_BEGIN_DECL

      | ^~~~~~~~~~~~~~

conftest.c:5:5: warning: "LIBGIT2_VER_MAJOR" is not defined, evaluates to 0 [-Wundef]

    5 | #if LIBGIT2_VER_MAJOR !=  || LIBGIT2_VER_MINOR !=

      |     ^~~~~~~~~~~~~~~~~

conftest.c:5:27: error: operator '!=' has no right operand

    5 | #if LIBGIT2_VER_MAJOR !=  || LIBGIT2_VER_MINOR !=

      |                           ^~

conftest.c:4: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ at end of input

    4 | 

cc1: note: unrecognized command-line option ‘-Wno-self-assign’ may have been intended to silence earlier diagnostics

cc1: note: unrecognized command-line option ‘-Wno-parentheses-equality’ may have been intended to silence earlier diagnostics

cc1: note: unrecognized command-line option ‘-Wno-constant-logical-operand’ may have been intended to silence earlier diagnostics

checked program was:

/* begin */

1: #include "ruby.h"

2: 

3: #include <git2/version.h>

4: 

5: #if LIBGIT2_VER_MAJOR !=  || LIBGIT2_VER_MINOR !=

6: #error libgit2 version is not compatible

7: #endif

/* end */

Reproduce the installation on Debian trixie-slim and inspect the generated conftest.c check against /usr/include/git2/version.h. Determine why the libgit2 version check fails, then verify that rugged installs successfully with the reported environment.