gh-115119: Detect _decimal dependencies using pkg-config (#115406)

pkg-config is supported for libmpdec 4.0.0 and newer.

Doc/using/configure.rst

@@ -389,6 +389,17 @@ Options for third-party dependencies
    C compiler and linker flags for ``libffi``, used by :mod:`ctypes` module,
    overriding ``pkg-config``.
 
+.. option:: LIBMPDEC_CFLAGS
+.. option:: LIBMPDEC_LIBS
+
+   C compiler and linker flags for ``libmpdec``, used by :mod:`decimal` module,
+   overriding ``pkg-config``.
+
+   .. note::
+
+      These environment variables have no effect unless
+      :option:`--with-system-libmpdec` is specified.
+
 .. option:: LIBLZMA_CFLAGS
 .. option:: LIBLZMA_LIBS
 
@@ -798,6 +809,8 @@ Libraries options
 
    .. versionadded:: 3.3
 
+   .. seealso:: :option:`LIBMPDEC_CFLAGS` and :option:`LIBMPDEC_LIBS`.
+
 .. option:: --with-readline=readline|editline
 
    Designate a backend library for the :mod:`readline` module.

Misc/NEWS.d/next/Build/2024-02-13-15-31-28.gh-issue-115119.FnQzAW.rst

@@ -0,0 +1,2 @@
+:program:`configure` now uses :program:`pkg-config` to detect :mod:`decimal`
+dependencies if the :option:`--with-system-libmpdec` option is given.

Modules/_decimal/_decimal.c

@@ -34,7 +34,19 @@
 #include "pycore_pystate.h"       // _PyThreadState_GET()
 #include "pycore_typeobject.h"
 #include "complexobject.h"
-#include "mpdecimal.h"
+
+#include <mpdecimal.h>
+
+// Reuse config from mpdecimal.h if present.
+#if defined(MPD_CONFIG_64)
+  #ifndef CONFIG_64
+    #define CONFIG_64 MPD_CONFIG_64
+  #endif
+#elif defined(MPD_CONFIG_32)
+  #ifndef CONFIG_32
+    #define CONFIG_32 MPD_CONFIG_32
+  #endif
+#endif
 
 #include <ctype.h>                // isascii()
 #include <stdlib.h>

configure

@@ -880,6 +880,7 @@ TCLTK_CFLAGS
 LIBSQLITE3_LIBS
 LIBSQLITE3_CFLAGS
 LIBMPDEC_INTERNAL
+LIBMPDEC_LIBS
 LIBMPDEC_CFLAGS
 MODULE__CTYPES_MALLOC_CLOSURE
 LIBFFI_LIBS
@@ -1148,6 +1149,8 @@ LIBUUID_CFLAGS
 LIBUUID_LIBS
 LIBFFI_CFLAGS
 LIBFFI_LIBS
+LIBMPDEC_CFLAGS
+LIBMPDEC_LIBS
 LIBSQLITE3_CFLAGS
 LIBSQLITE3_LIBS
 TCLTK_CFLAGS
@@ -1969,6 +1972,10 @@ Some influential environment variables:
   LIBFFI_CFLAGS
               C compiler flags for LIBFFI, overriding pkg-config
   LIBFFI_LIBS linker flags for LIBFFI, overriding pkg-config
+  LIBMPDEC_CFLAGS
+              C compiler flags for LIBMPDEC, overriding pkg-config
+  LIBMPDEC_LIBS
+              linker flags for LIBMPDEC, overriding pkg-config
   LIBSQLITE3_CFLAGS
               C compiler flags for LIBSQLITE3, overriding pkg-config
   LIBSQLITE3_LIBS
@@ -14591,28 +14598,92 @@ printf "%s\n" "$with_system_libmpdec" >&6; }
 if test "x$with_system_libmpdec" = xyes
 then :
 
+pkg_failed=no
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for libmpdec" >&5
+printf %s "checking for libmpdec... " >&6; }
+
+if test -n "$LIBMPDEC_CFLAGS"; then
+    pkg_cv_LIBMPDEC_CFLAGS="$LIBMPDEC_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libmpdec") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_LIBMPDEC_CFLAGS=`$PKG_CONFIG --cflags "libmpdec" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$LIBMPDEC_LIBS"; then
+    pkg_cv_LIBMPDEC_LIBS="$LIBMPDEC_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libmpdec\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libmpdec") 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_LIBMPDEC_LIBS=`$PKG_CONFIG --libs "libmpdec" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libmpdec" 2>&1`
+        else
+	        LIBMPDEC_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libmpdec" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$LIBMPDEC_PKG_ERRORS" >&5
+
 	LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
-  LIBMPDEC_LDFLAGS=${LIBMPDEC_LDFLAGS-"-lmpdec"}
+     LIBMPDEC_LIBS=${LIBMPDEC_LIBS-"-lmpdec -lm"}
      LIBMPDEC_INTERNAL=
+elif test $pkg_failed = untried; then
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+	LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
+     LIBMPDEC_LIBS=${LIBMPDEC_LIBS-"-lmpdec -lm"}
+     LIBMPDEC_INTERNAL=
+else
+	LIBMPDEC_CFLAGS=$pkg_cv_LIBMPDEC_CFLAGS
+	LIBMPDEC_LIBS=$pkg_cv_LIBMPDEC_LIBS
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
 
+fi
 else $as_nop
-
   LIBMPDEC_CFLAGS="-I\$(srcdir)/Modules/_decimal/libmpdec"
-  LIBMPDEC_LDFLAGS="-lm \$(LIBMPDEC_A)"
+   LIBMPDEC_LIBS="-lm \$(LIBMPDEC_A)"
    LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"
+fi
 
+# Disable forced inlining in debug builds, see GH-94847
 if test "x$with_pydebug" = xyes
 then :
-
   as_fn_append LIBMPDEC_CFLAGS " -DTEST_COVERAGE"
-
 fi
 
-fi
-
-
-
-
 # Check whether _decimal should use a coroutine-local or thread-local context
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for --with-decimal-contextvar" >&5
 printf %s "checking for --with-decimal-contextvar... " >&6; }
@@ -14636,6 +14707,8 @@ fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $with_decimal_contextvar" >&5
 printf "%s\n" "$with_decimal_contextvar" >&6; }
 
+if test "x$with_system_libmpdec" = xno
+then :
   # Check for libmpdec machine flavor
    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for decimal libmpdec machine" >&5
 printf %s "checking for decimal libmpdec machine... " >&6; }
@@ -14699,6 +14772,7 @@ case $libmpdec_machine in #(
     as_fn_error $? "_decimal: unsupported architecture" "$LINENO" 5
     ;;
 esac
+fi
 
 if test "$have_ipa_pure_const_bug" = yes; then
     # Some versions of gcc miscompile inline asm:
@@ -14717,6 +14791,9 @@ fi
 
 
 
+
+
+
   if test "$ac_sys_system" = "Emscripten" -a -z "$LIBSQLITE3_CFLAGS" -a -z "$LIBSQLITE3_LIBS"
 then :
 
@@ -30310,7 +30387,7 @@ fi
 then :
 
     as_fn_append MODULE_BLOCK "MODULE__DECIMAL_CFLAGS=$LIBMPDEC_CFLAGS$as_nl"
-    as_fn_append MODULE_BLOCK "MODULE__DECIMAL_LDFLAGS=$LIBMPDEC_LDFLAGS$as_nl"
+    as_fn_append MODULE_BLOCK "MODULE__DECIMAL_LDFLAGS=$LIBMPDEC_LIBS$as_nl"
 
 fi
    if test "$py_cv_module__decimal" = yes; then

configure.ac

@@ -3961,23 +3961,21 @@ AC_ARG_WITH(
   [with_system_libmpdec="no"])
 AC_MSG_RESULT([$with_system_libmpdec])
 
-AS_VAR_IF([with_system_libmpdec], [yes], [
-  LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
-  LIBMPDEC_LDFLAGS=${LIBMPDEC_LDFLAGS-"-lmpdec"}
-  LIBMPDEC_INTERNAL=
-], [
-  LIBMPDEC_CFLAGS="-I\$(srcdir)/Modules/_decimal/libmpdec"
-  LIBMPDEC_LDFLAGS="-lm \$(LIBMPDEC_A)"
-  LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"
+AS_VAR_IF(
+  [with_system_libmpdec], [yes],
+  [PKG_CHECK_MODULES(
+    [LIBMPDEC], [libmpdec], [],
+    [LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
+     LIBMPDEC_LIBS=${LIBMPDEC_LIBS-"-lmpdec -lm"}
+     LIBMPDEC_INTERNAL=])],
+  [LIBMPDEC_CFLAGS="-I\$(srcdir)/Modules/_decimal/libmpdec"
+   LIBMPDEC_LIBS="-lm \$(LIBMPDEC_A)"
+   LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"])
 
-  dnl Disable forced inlining in debug builds, see GH-94847
-  AS_VAR_IF([with_pydebug], [yes], [
-    AS_VAR_APPEND([LIBMPDEC_CFLAGS], [" -DTEST_COVERAGE"])
-  ])
-])
-
-AC_SUBST([LIBMPDEC_CFLAGS])
-AC_SUBST([LIBMPDEC_INTERNAL])
+# Disable forced inlining in debug builds, see GH-94847
+AS_VAR_IF(
+  [with_pydebug], [yes],
+  [AS_VAR_APPEND([LIBMPDEC_CFLAGS], [" -DTEST_COVERAGE"])])
 
 # Check whether _decimal should use a coroutine-local or thread-local context
 AC_MSG_CHECKING([for --with-decimal-contextvar])
@@ -3998,7 +3996,9 @@ fi
 
 AC_MSG_RESULT([$with_decimal_contextvar])
 
-# Check for libmpdec machine flavor
+AS_VAR_IF(
+  [with_system_libmpdec], [no],
+  [# Check for libmpdec machine flavor
    AC_MSG_CHECKING([for decimal libmpdec machine])
    AS_CASE([$ac_sys_system],
      [Darwin*], [libmpdec_system=Darwin],
@@ -4041,7 +4041,7 @@ AS_CASE([$libmpdec_machine],
      [ansi-legacy], [AS_VAR_APPEND([LIBMPDEC_CFLAGS], [" -DCONFIG_32=1 -DANSI=1 -DLEGACY_COMPILER=1"])],
      [universal],   [AS_VAR_APPEND([LIBMPDEC_CFLAGS], [" -DUNIVERSAL=1"])],
      [AC_MSG_ERROR([_decimal: unsupported architecture])]
-)
+   )])
 
 if test "$have_ipa_pure_const_bug" = yes; then
     # Some versions of gcc miscompile inline asm:
@@ -4056,6 +4056,9 @@ if test "$have_glibc_memmove_bug" = yes; then
     AS_VAR_APPEND([LIBMPDEC_CFLAGS], [" -U_FORTIFY_SOURCE"])
 fi
 
+AC_SUBST([LIBMPDEC_CFLAGS])
+AC_SUBST([LIBMPDEC_INTERNAL])
+
 
 dnl detect sqlite3 from Emscripten emport
 PY_CHECK_EMSCRIPTEN_PORT([LIBSQLITE3], [-sUSE_SQLITE3])
@@ -7643,7 +7646,7 @@ PY_STDLIB_MOD([_curses_panel],
   [], [test "$have_panel" != "no"],
   [$PANEL_CFLAGS $CURSES_CFLAGS], [$PANEL_LIBS $CURSES_LIBS]
 )
-PY_STDLIB_MOD([_decimal], [], [], [$LIBMPDEC_CFLAGS], [$LIBMPDEC_LDFLAGS])
+PY_STDLIB_MOD([_decimal], [], [], [$LIBMPDEC_CFLAGS], [$LIBMPDEC_LIBS])
 PY_STDLIB_MOD([_dbm],
   [test -n "$with_dbmliborder"], [test "$have_dbm" != "no"],
   [$DBM_CFLAGS], [$DBM_LIBS])