Add ./configure --enable-static to compile the opam binary statically

.github/scripts/cygwin.cmd

@@ -49,8 +49,6 @@ if not exist %CYGWIN_CACHE_DIR%\%CYGWIN_DISTRO%\cache.tar (
 ::        C:\Windows\system32 (overriding curl, bash, etc. in System32) but after Mercurial
 ::        and Git (so that they are not overridden).
 set Path=C:\Program Files\Mercurial;C:\Program Files\Git\cmd;%CYGWIN_ROOT%\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\
-if "%3" equ "i686-w64-mingw32" set Path=%CYGWIN_ROOT%\usr\%3\sys-root\mingw\bin;%Path%
-if "%3" equ "x86_64-w64-mingw32" set Path=%CYGWIN_ROOT%\usr\%3\sys-root\mingw\bin;%Path%
 if "%3" equ "x86_64-pc-cygwin" set Path=%CYGWIN_ROOT%\bin;%Path%
 
 ::echo %CYGWIN_ROOT%\bin>> %GITHUB_PATH%

.github/workflows/ci.ml

@@ -339,6 +339,7 @@ let main_build_job ~analyse_job ~cygwin_job ?section runner start_version ~oc ~w
     ++ build_cache OCaml platform "${{ matrix.ocamlv }}" host
     ++ run "Build" ["bash -exu .github/scripts/main/main.sh " ^ host]
     ++ not_on Windows (run "Test (basic)" ["bash -exu .github/scripts/main/test.sh"])
+    ++ only_on Windows (run ~cond:(Predicate(false, EndsWith("matrix.host", "-pc-cygwin"))) "Test \"static\" binaries on Windows" ["ldd ./opam.exe | test \"$(grep -v -F /cygdrive/c/Windows/)\" = ''"])
     ++ only_on Windows (run "Test (basic - Cygwin)" ~cond:(Predicate(true, EndsWith("matrix.host", "-pc-cygwin"))) ["bash -exu .github/scripts/main/test.sh"])
     ++ only_on Windows (run "Test (basic - native Windows)" ~env:[("OPAMROOT", {|D:\a\opam\opam\.opam|})] ~shell:"cmd" ~cond:(Predicate(false, EndsWith("matrix.host", "-pc-cygwin")))
          ({|set Path=D:\Cache\ocaml-local\bin;%Path%|} ::

.github/workflows/main.yml

@@ -204,6 +204,9 @@ jobs:
       run: bash -exu .github/scripts/main/ocaml-cache.sh ${{ runner.os }} ${{ matrix.ocamlv }} ${{ matrix.host }}
     - name: Build
       run: bash -exu .github/scripts/main/main.sh ${{ matrix.host }}
+    - name: Test "static" binaries on Windows
+      if: endsWith(matrix.host, '-pc-cygwin') == false
+      run: ldd ./opam.exe | test "$(grep -v -F /cygdrive/c/Windows/)" = ''
     - name: Test (basic - Cygwin)
       if: endsWith(matrix.host, '-pc-cygwin')
       run: bash -exu .github/scripts/main/test.sh

configure.ac

@@ -76,6 +76,12 @@ AC_ARG_WITH([private_runtime],
   AS_HELP_STRING([--with-private-runtime],[For a mingw-w64 build, manifest the runtime DLLs locally in Opam.Runtime.arch]),,[with_private_runtime=no]
 )
 
+AC_ARG_ENABLE([static],
+  AS_HELP_STRING([--enable-static],
+    [Compile the opam binary statically. Only Musl-based Linux distributions and Windows with MinGW is currently supported. This is the default on Windows with MinGW]),
+  [],
+  [enable_static=auto])
+
 AC_ARG_ENABLE([cold_check],
   AS_HELP_STRING([--enable-cold-check],[Fail on some check necessary for make cold]),[COLD_CHECK=yes],[]
 )
@@ -113,6 +119,9 @@ AC_MSG_CHECKING([for compiler system])
 SYSTEM=`$OCAML shell/print_config.ml system 2>/dev/null | grep -F -v "Cannot find" || $OCAMLC -config | tr -d '\r' | sed -n -e "s/system: //p"`
 AC_MSG_RESULT([$SYSTEM])
 AC_SUBST(SYSTEM)
+AC_MSG_CHECKING([for compiler target])
+TARGET=`$OCAML shell/print_config.ml target 2>/dev/null | grep -F -v "Cannot find" || $OCAMLC -config | tr -d '\r' | sed -n -e "s/target: //p"`
+AC_MSG_RESULT([$TARGET])
 
 LIB_PREPEND=
 INC_PREPEND=
@@ -327,6 +336,33 @@ AS_IF([test "x${with_private_runtime}" != "xno"],[
 ],[CONF_MANIFEST_O=])
 AC_SUBST(CONF_MANIFEST_O)
 
+# Handle --enable-static
+AC_MSG_CHECKING([for linking method])
+support_static=no
+default_static=no
+AS_CASE([$TARGET],
+  [*-linux-musl*],[
+    support_static=yes
+    platform_dependant_stuff="-cclib -lstdc++ -cclib -static-libgcc -cclib -static"
+  ],
+  [*-*-mingw32*],[
+    support_static=yes
+    default_static=yes
+    # NOTE: On Windows, the Windows specific dlls should stay dynamic for security reasons
+    # NOTE: -l:libstdc++.a is necessary (vs. -lstdc++) as flexlink will use libstdc++.dll.a
+    # which still depends on the DLL at runtime instead of libstdc++.a (that looks like a bug in flexlink)
+    platform_dependant_stuff="-cclib -lopam_stubs_win32_stubs -cclib -l:libstdc++.a -cclib -l:libpthread.a -cclib -Wl,-static -cclib -ladvapi32 -cclib -lgdi32 -cclib -luser32 -cclib -lshell32"
+  ])
+AS_CASE([${support_static},${enable_static}],
+  [no,yes],[AC_MSG_ERROR([--enable-static is not available on this platform (${TARGET}).])],
+  [*,auto],[enable_static=${default_static}])
+AS_IF([test "${enable_static}" = yes],[
+  echo "(-noautolink -cclib -lunix -cclib -lmccs_stubs -cclib -lmccs_glpk_stubs -cclib -lsha_stubs ${platform_dependant_stuff})" > src/client/linking.sexp
+  AC_MSG_RESULT([static])
+],[
+  AC_MSG_RESULT([shared])
+])
+
 echo
 
 # Dependencies

master_changes.md

@@ -73,6 +73,7 @@ users)
 ## Build
   * Vendor mccs.1.1+17 [#5769 @kit-ty-kate]
   * Require mccs >= 1.1+17 [#5769 @kit-ty-kate]
+  * Add ./configure --enable-static to compile the opam binary statically [#5680 @kit-ty-kate - fixes #5647]
 
 ## Infrastructure