use javac -h instead of javah for Java >= 11

(should fix the compilation error with openjdk 11)

configure

@@ -455,10 +455,23 @@ if test "x$java_prefix" != "x"; then JAVA_HOME="$java_prefix"; fi
 if test "x$JAVA_HOME" != "x"; then PATH=$JAVA_HOME/bin:$PATH; fi
 if test $has_java -eq 1; then searchbin "java"; has_java=$?; java="$path"; fi
 if test $has_java -eq 1; then searchbin "javac"; has_java=$?; javac="$path"; fi
-if test $has_java -eq 1; then searchbin "javah"; has_java=$?; javah="$path"; fi
 if test $has_java -eq 1; then searchbin "javadoc"; has_java=$?; javadoc="$path"; fi
 if test $has_java -eq 1; then searchbin "jar"; has_java=$?; jar="$path"; fi
 
+# check Java version
+if test $has_java -eq 1
+then
+    java_version=`$java -version 2>&1 | head -1 | cut -d'"' -f2 | sed '/^1\./s///' | cut -d'.' -f1`
+    if test $java_version -ge 11
+    then
+        # new Java use javac -h
+        javac_has_h=1
+    else
+        # old Java, use javah
+        if test $has_java -eq 1; then searchbin "javah"; has_java=$?; javah="$path"; fi
+    fi
+fi
+
 # check jni includes
 if test $has_java -eq 1
 then
@@ -518,7 +531,7 @@ detected configuration:
    optional OCamlFind support   $has_ocamlfind
    optional plugins support     $has_ocaml_plugins
    optional C++ support         $has_cxx
-   optional Java support        $has_java
+   optional Java support        $has_java ($java_version)
    optional PPL support         $has_ppl
 
    installation path            $apron_prefix
@@ -565,6 +578,7 @@ JAVA_PREFIX = $apron_prefix/lib
 JAVA      = $java
 JAVAC     = $javac -Xlint:unchecked
 JAVAH     = $javah
+JAVAC_HAS_H = $javac_has_h
 JAVADOC   = $javadoc
 JAR       = $jar
 java_home = ${JAVA_HOME}

japron/Makefile

@@ -110,37 +110,58 @@ SOINST     = libjgmp.$(EXT_DLL) libjapron.$(EXT_DLL)
 
 all: $(GMPALL) $(APRONALL) $(JAVAINST) $(SOINST)
 
+ifneq ($(JAVAC_HAS_H),)
+
+$(GMPCLASS): $(GMPJ)
+	$(JAVAC) -h gmp $+
+
+else
+
 $(GMPCLASS): $(GMPJ)
 	$(JAVAC) $+
 
+gmp/gmp_%.h: gmp/%.java
+	$(JAVAH) -o $@ gmp.$*
+	touch $@
+
+endif
+
 gmp/%.o: gmp/%.c $(GMPH) gmp/jgmp.h
 	$(CC) $(CFLAGSN) -c $(IFLAGS) $< -o $@
 
 libjgmp.$(EXT_DLL): gmp/jgmp.o $(GMPO)
 	$(CC) $(CFLAGSN) -shared $+ -o $@ $(LFLAGS) $(GMPLIBS)
 
-gmp/gmp_%.h: gmp/%.java
-	$(JAVAH) -o $@ gmp.$* 
-	touch $@
-
 gmp.jar: $(GMPCLASS)
 	$(JAR) cf $@ $+
 	$(JAR) i $@
 
 
+ifneq ($(JAVAC_HAS_H),)
+
+$(APRONCLASS): $(APRONJ)
+	$(JAVAC) -h apron $+
+
+# javac -h does not generate an apron_Var.h
+apron/apron_Var.h:
+	touch $@
+
+else
+
 $(APRONCLASS): $(APRONJ)
 	$(JAVAC) $+
 
+apron/apron_%.h: apron/%.java
+	$(JAVAH) -o $@ apron.$*
+	touch $@
+endif
+
 apron/%.o: apron/%.c $(APRONH)  gmp/jgmp.h apron/japron.h
 	$(CC) $(CFLAGSN) -c $(IFLAGS) -Igmp $< -o $@
 
 libjapron.$(EXT_DLL): apron/japron.o $(APRONO)
 	$(CC) $(CFLAGSN) -shared $+ -o $@ $(LFLAGS) $(APRONLIBS)
 
-apron/apron_%.h: apron/%.java
-	$(JAVAH) -o $@ apron.$* 
-	touch $@
-
 apron.jar: $(APRONCLASS)
 	$(JAR) cf $@ $+
 	$(JAR) i $@