Build system: enable the interleaved API in MEX files for Octave ⩾ 8.4.0

Unfortunately it is not possible to enable it for all supported Octave
versions (which would have allowed us to remove the old codepath), because of
this bug: https://savannah.gnu.org/bugs/?64687

meson.build

@@ -203,7 +203,17 @@ else # Octave build
   exe_rpath = octlibdir
   exe_link_args = [ '-L' + octlibdir ] + octave_libs
 
+  # Minimal Octave version for which we enable the interleaved API.
+  # Octave 7 is supposed to support it, but it crashes due to this bug:
+  #  https://savannah.gnu.org/bugs/?64687
+  octave_minimal_version_for_interleaved_api = '8.4.0'
+
   octave_defs = [ '-DOCTAVE_MEX_FILE', '-DMEXEXT=".mex"' ]
+  if octave_version.version_compare('>=' + octave_minimal_version_for_interleaved_api)
+    # Mimic the behaviour of mkoctfile which adds this define when the
+    # interleaved API is requested.
+    octave_defs += '-DMX_HAS_INTERLEAVED_COMPLEX=1'
+  endif
 
   mex_kwargs = { 'name_prefix' : '',
                  'name_suffix' : 'mex',
@@ -215,6 +225,12 @@ else # Octave build
                  'install' : true,
                  'install_dir' : 'lib/dynare/mex/octave' }
 
+  if octave_version.version_compare('>=' + octave_minimal_version_for_interleaved_api)
+    # Mimic the behaviour of mkoctfile which compiles in a similar source file
+    # when interleaved API is requested.
+    mex_kwargs += { 'sources' : 'mex/sources/octave_interleaved.c' }
+  endif
+
   # The -L argument is useful when cross-compiling.
   blas_dep = declare_dependency(link_args : [ '-L' + (octlibdir / '../..') ] + run_command(mkoctfile_exe, '-p', 'BLAS_LIBS', check : true).stdout().split())
   lapack_dep = declare_dependency(link_args : run_command(mkoctfile_exe, '-p', 'LAPACK_LIBS', check : true).stdout().split(),

mex/sources/defines.F08

@@ -1 +1,7 @@
-#define MX_HAS_INTERLEAVED_COMPLEX (defined(MATLAB_MEX_FILE))
+! Under Octave, MX_HAS_INTERLEAVED_COMPLEX is defined through the command-line
+! defines (as is done by mkoctfile), while under MATLAB it is defined through
+! the present file (because it is defined by mex.h there).
+
+#ifdef MATLAB_MEX_FILE
+# define MX_HAS_INTERLEAVED_COMPLEX 1
+#endif

mex/sources/matlab_mex.F08

@@ -13,6 +13,9 @@
 !   was an API_VER2 define for those.
 !   For each function, the information can be retrieved from either matrix.h or
 !   mex.h.
+!   Under Octave, when the interleaved API is used, some functions have a
+!   different symbol name, handled through the API_VER_INTERLEAVED define;
+!   see octave/mexproto.h for the list of affected functions.
 ! — C passes arguments by value, so the “value” keyword is often needed
 ! — Strings passed to C must be null terminated (hence a wrapper is needed to
 !   append c_null_char)
@@ -48,15 +51,21 @@
 ! You should have received a copy of the GNU General Public License
 ! along with Dynare.  If not, see <https://www.gnu.org/licenses/>.
 
+#include "defines.F08"
+
 #ifdef MATLAB_MEX_FILE
 # define API_VER "_800"
+# define API_VER_INTERLEAVED "_800"
 #else
 ! Octave
 # define API_VER ""
+# if MX_HAS_INTERLEAVED_COMPLEX
+#  define API_VER_INTERLEAVED "_interleaved"
+# else
+#  define API_VER_INTERLEAVED ""
+# endif
 #endif
 
-#include "defines.F08"
-
 !!! C Matrix API
 !!! Listed in same order as https://fr.mathworks.com/help/matlab/cc-mx-matrix-library.html
 module matlab_mat
@@ -109,14 +118,14 @@ module matlab_mat
      !! Create, Query, and Access Data Types
 
      ! Numeric types
-     type(c_ptr) function mxCreateDoubleMatrix(m, n, ComplexFlag) bind(c, name="mxCreateDoubleMatrix"//API_VER)
+     type(c_ptr) function mxCreateDoubleMatrix(m, n, ComplexFlag) bind(c, name="mxCreateDoubleMatrix"//API_VER_INTERLEAVED)
        use iso_c_binding
        import :: mwSize, mxComplexity
        integer(mwSize), intent(in), value :: m, n
        integer(mxComplexity), intent(in), value :: ComplexFlag
      end function mxCreateDoubleMatrix
 
-     type(c_ptr) function mxCreateDoubleScalar(value) bind(c, name="mxCreateDoubleScalar"//API_VER)
+     type(c_ptr) function mxCreateDoubleScalar(value) bind(c, name="mxCreateDoubleScalar"//API_VER_INTERLEAVED)
        use iso_c_binding
        real(c_double), intent(in), value :: value
      end function mxCreateDoubleScalar
@@ -171,7 +180,7 @@ module matlab_mat
 #endif
 
      ! Sparse
-     type(c_ptr) function mxCreateSparse(m, n, nzmax, ComplexFlag) bind(c, name="mxCreateSparse"//API_VER)
+     type(c_ptr) function mxCreateSparse(m, n, nzmax, ComplexFlag) bind(c, name="mxCreateSparse"//API_VER_INTERLEAVED)
        use iso_c_binding
        import :: mwSize, mxComplexity
        integer(mwSize), intent(in), value :: m, n, nzmax
@@ -216,7 +225,7 @@ module matlab_mat
        type(c_ptr), intent(in), value :: array_ptr
      end function mxIsLogicalScalar
 
-     type(c_ptr) function mxCreateLogicalScalar(value) bind(c, name="mxCreateLogicalScalar"//API_VER)
+     type(c_ptr) function mxCreateLogicalScalar(value) bind(c, name="mxCreateLogicalScalar"//API_VER_INTERLEAVED)
        use iso_c_binding
        import :: mxLogical
        logical(mxLogical), intent(in), value :: value
@@ -235,7 +244,8 @@ module matlab_mat
      end function mxIsClass_internal
 
      ! Structure
-     type(c_ptr) function mxCreateStructMatrix_internal(m, n, nfields, fieldnames) bind(c, name="mxCreateStructMatrix"//API_VER)
+     type(c_ptr) function mxCreateStructMatrix_internal(m, n, nfields, fieldnames) bind(c, name="mxCreateStructMatrix" &
+          //API_VER_INTERLEAVED)
        use iso_c_binding
        import :: mwSize
        integer(mwSize), intent(in), value :: m, n

mex/sources/octave_interleaved.c

@@ -0,0 +1,4 @@
+/* This file must be compiled in any Octave MEX for which we want the
+   interleaved API. This is similar to what mkoctfile does when this API is
+   requested. */
+const int __mx_has_interleaved_complex__ = 1;