[libxml2] Fix -Wcast-function-type warnings (GCC 8)

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 19f0950d30208c4a37fe90b25ed82c5bdc44287a
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Jan 1 16:38:42 2019 +0100

    Fix -Wcast-function-type warnings (GCC 8)
    
    Use xmlGenericError instead of fprintf as error handler. It also prints
    to stderr by default.

 debugXML.c    | 16 +++++-----------
 error.c       |  2 +-
 testRelax.c   | 12 +++---------
 testSchemas.c | 12 +++---------
 xmllint.c     | 50 ++++++++++++++++----------------------------------
 5 files changed, 28 insertions(+), 64 deletions(-)
---
diff --git a/debugXML.c b/debugXML.c
index c98db0bc..79bb50d1 100644
--- a/debugXML.c
+++ b/debugXML.c
@@ -2363,10 +2363,7 @@ xmlShellRNGValidate(xmlShellCtxtPtr sctxt, char *schemas,
     int ret;
 
     ctxt = xmlRelaxNGNewParserCtxt(schemas);
-    xmlRelaxNGSetParserErrors(ctxt,
-           (xmlRelaxNGValidityErrorFunc) fprintf,
-           (xmlRelaxNGValidityWarningFunc) fprintf,
-           stderr);
+    xmlRelaxNGSetParserErrors(ctxt, xmlGenericError, xmlGenericError, NULL);
     relaxngschemas = xmlRelaxNGParse(ctxt);
     xmlRelaxNGFreeParserCtxt(ctxt);
     if (relaxngschemas == NULL) {
@@ -2375,10 +2372,7 @@ xmlShellRNGValidate(xmlShellCtxtPtr sctxt, char *schemas,
        return(-1);
     }
     vctxt = xmlRelaxNGNewValidCtxt(relaxngschemas);
-    xmlRelaxNGSetValidErrors(vctxt,
-           (xmlRelaxNGValidityErrorFunc) fprintf,
-           (xmlRelaxNGValidityWarningFunc) fprintf,
-           stderr);
+    xmlRelaxNGSetValidErrors(vctxt, xmlGenericError, xmlGenericError, NULL);
     ret = xmlRelaxNGValidateDoc(vctxt, sctxt->doc);
     if (ret == 0) {
        fprintf(stderr, "%s validates\n", sctxt->filename);
@@ -2647,9 +2641,9 @@ xmlShellValidate(xmlShellCtxtPtr ctxt, char *dtd,
     int res = -1;
 
     if ((ctxt == NULL) || (ctxt->doc == NULL)) return(-1);
-    vctxt.userData = stderr;
-    vctxt.error = (xmlValidityErrorFunc) fprintf;
-    vctxt.warning = (xmlValidityWarningFunc) fprintf;
+    vctxt.userData = NULL;
+    vctxt.error = xmlGenericError;
+    vctxt.warning = xmlGenericError;
 
     if ((dtd == NULL) || (dtd[0] == 0)) {
         res = xmlValidateDocument(&vctxt, ctxt->doc);
diff --git a/error.c b/error.c
index 50e9e6f8..9d39f79e 100644
--- a/error.c
+++ b/error.c
@@ -631,7 +631,7 @@ __xmlRaiseError(xmlStructuredErrorFunc schannel,
        (channel == xmlParserValidityError) ||
        (channel == xmlParserValidityWarning))
        xmlReportError(to, ctxt, str, NULL, NULL);
-    else if ((channel == (xmlGenericErrorFunc) fprintf) ||
+    else if (((void(*)(void)) channel == (void(*)(void)) fprintf) ||
              (channel == xmlGenericErrorDefaultFunc))
        xmlReportError(to, ctxt, str, channel, data);
     else
diff --git a/testRelax.c b/testRelax.c
index 8e94a7a8..3549f938 100644
--- a/testRelax.c
+++ b/testRelax.c
@@ -101,9 +101,7 @@ int main(int argc, char **argv) {
                    ctxt = xmlRelaxNGNewMemParserCtxt((char *)base,info.st_size);
 
                    xmlRelaxNGSetParserErrors(ctxt,
-                           (xmlRelaxNGValidityErrorFunc) fprintf,
-                           (xmlRelaxNGValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    schema = xmlRelaxNGParse(ctxt);
                    xmlRelaxNGFreeParserCtxt(ctxt);
                    munmap((char *) base, info.st_size);
@@ -112,9 +110,7 @@ int main(int argc, char **argv) {
                {
                    ctxt = xmlRelaxNGNewParserCtxt(argv[i]);
                    xmlRelaxNGSetParserErrors(ctxt,
-                           (xmlRelaxNGValidityErrorFunc) fprintf,
-                           (xmlRelaxNGValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    schema = xmlRelaxNGParse(ctxt);
                    xmlRelaxNGFreeParserCtxt(ctxt);
                }
@@ -144,9 +140,7 @@ int main(int argc, char **argv) {
 
                    ctxt = xmlRelaxNGNewValidCtxt(schema);
                    xmlRelaxNGSetValidErrors(ctxt,
-                           (xmlRelaxNGValidityErrorFunc) fprintf,
-                           (xmlRelaxNGValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    ret = xmlRelaxNGValidateDoc(ctxt, doc);
                    if (ret == 0) {
                        printf("%s validates\n", argv[i]);
diff --git a/testSchemas.c b/testSchemas.c
index b98e6313..fc39862c 100644
--- a/testSchemas.c
+++ b/testSchemas.c
@@ -97,9 +97,7 @@ int main(int argc, char **argv) {
                    ctxt = xmlSchemaNewMemParserCtxt((char *)base,info.st_size);
 
                    xmlSchemaSetParserErrors(ctxt,
-                           (xmlSchemaValidityErrorFunc) fprintf,
-                           (xmlSchemaValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    schema = xmlSchemaParse(ctxt);
                    xmlSchemaFreeParserCtxt(ctxt);
                    munmap((char *) base, info.st_size);
@@ -108,9 +106,7 @@ int main(int argc, char **argv) {
                {
                    ctxt = xmlSchemaNewParserCtxt(argv[i]);
                    xmlSchemaSetParserErrors(ctxt,
-                           (xmlSchemaValidityErrorFunc) fprintf,
-                           (xmlSchemaValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    schema = xmlSchemaParse(ctxt);
                    xmlSchemaFreeParserCtxt(ctxt);
                }
@@ -135,9 +131,7 @@ int main(int argc, char **argv) {
 
                    ctxt = xmlSchemaNewValidCtxt(schema);
                    xmlSchemaSetValidErrors(ctxt,
-                           (xmlSchemaValidityErrorFunc) fprintf,
-                           (xmlSchemaValidityWarningFunc) fprintf,
-                           stderr);
+                            xmlGenericError, xmlGenericError, NULL);
                    ret = xmlSchemaValidateDoc(ctxt, doc);
                    if (ret == 0) {
                        printf("%s validates\n", argv[i]);
diff --git a/xmllint.c b/xmllint.c
index d6f5eb0e..970a84ee 100644
--- a/xmllint.c
+++ b/xmllint.c
@@ -1652,10 +1652,7 @@ testSAX(const char *filename) {
        xmlSchemaValidCtxtPtr vctxt;
 
        vctxt = xmlSchemaNewValidCtxt(wxschemas);
-       xmlSchemaSetValidErrors(vctxt,
-               (xmlSchemaValidityErrorFunc) fprintf,
-               (xmlSchemaValidityWarningFunc) fprintf,
-               stderr);
+       xmlSchemaSetValidErrors(vctxt, xmlGenericError, xmlGenericError, NULL);
        xmlSchemaValidateSetFilename(vctxt, filename);
 
        ret = xmlSchemaValidateStream(vctxt, buf, 0, handler,
@@ -2760,9 +2757,9 @@ static void parseAndPrintFile(char *filename, xmlParserCtxtPtr rectxt) {
                        "Couldn't allocate validation context\n");
                exit(-1);
            }
-           cvp->userData = (void *) stderr;
-           cvp->error    = (xmlValidityErrorFunc) fprintf;
-           cvp->warning  = (xmlValidityWarningFunc) fprintf;
+           cvp->userData = NULL;
+           cvp->error    = xmlGenericError;
+           cvp->warning  = xmlGenericError;
 
            if ((timing) && (!repeat)) {
                startTimer();
@@ -2796,9 +2793,9 @@ static void parseAndPrintFile(char *filename, xmlParserCtxtPtr rectxt) {
        if ((timing) && (!repeat)) {
            startTimer();
        }
-       cvp->userData = (void *) stderr;
-       cvp->error    = (xmlValidityErrorFunc) fprintf;
-       cvp->warning  = (xmlValidityWarningFunc) fprintf;
+       cvp->userData = NULL;
+       cvp->error    = xmlGenericError;
+       cvp->warning  = xmlGenericError;
        if (!xmlValidateDocument(cvp, doc)) {
            xmlGenericError(xmlGenericErrorContext,
                    "Document %s does not validate\n", filename);
@@ -2828,10 +2825,8 @@ static void parseAndPrintFile(char *filename, xmlParserCtxtPtr rectxt) {
            flag |= XML_SCHEMATRON_OUT_QUIET;
        ctxt = xmlSchematronNewValidCtxt(wxschematron, flag);
 #if 0
-       xmlSchematronSetValidErrors(ctxt,
-               (xmlSchematronValidityErrorFunc) fprintf,
-               (xmlSchematronValidityWarningFunc) fprintf,
-               stderr);
+       xmlSchematronSetValidErrors(ctxt, xmlGenericError, xmlGenericError,
+                NULL);
 #endif
        ret = xmlSchematronValidateDoc(ctxt, doc);
        if (ret == 0) {
@@ -2860,10 +2855,7 @@ static void parseAndPrintFile(char *filename, xmlParserCtxtPtr rectxt) {
        }
 
        ctxt = xmlRelaxNGNewValidCtxt(relaxngschemas);
-       xmlRelaxNGSetValidErrors(ctxt,
-               (xmlRelaxNGValidityErrorFunc) fprintf,
-               (xmlRelaxNGValidityWarningFunc) fprintf,
-               stderr);
+       xmlRelaxNGSetValidErrors(ctxt, xmlGenericError, xmlGenericError, NULL);
        ret = xmlRelaxNGValidateDoc(ctxt, doc);
        if (ret == 0) {
            fprintf(stderr, "%s validates\n", filename);
@@ -2888,10 +2880,7 @@ static void parseAndPrintFile(char *filename, xmlParserCtxtPtr rectxt) {
        }
 
        ctxt = xmlSchemaNewValidCtxt(wxschemas);
-       xmlSchemaSetValidErrors(ctxt,
-               (xmlSchemaValidityErrorFunc) fprintf,
-               (xmlSchemaValidityWarningFunc) fprintf,
-               stderr);
+       xmlSchemaSetValidErrors(ctxt, xmlGenericError, xmlGenericError, NULL);
        ret = xmlSchemaValidateDoc(ctxt, doc);
        if (ret == 0) {
            fprintf(stderr, "%s validates\n", filename);
@@ -3552,10 +3541,8 @@ main(int argc, char **argv) {
        }
        ctxt = xmlSchematronNewParserCtxt(schematron);
 #if 0
-       xmlSchematronSetParserErrors(ctxt,
-               (xmlSchematronValidityErrorFunc) fprintf,
-               (xmlSchematronValidityWarningFunc) fprintf,
-               stderr);
+       xmlSchematronSetParserErrors(ctxt, xmlGenericError, xmlGenericError,
+                NULL);
 #endif
        wxschematron = xmlSchematronParse(ctxt);
        if (wxschematron == NULL) {
@@ -3585,10 +3572,8 @@ main(int argc, char **argv) {
            startTimer();
        }
        ctxt = xmlRelaxNGNewParserCtxt(relaxng);
-       xmlRelaxNGSetParserErrors(ctxt,
-               (xmlRelaxNGValidityErrorFunc) fprintf,
-               (xmlRelaxNGValidityWarningFunc) fprintf,
-               stderr);
+       xmlRelaxNGSetParserErrors(ctxt, xmlGenericError, xmlGenericError,
+                NULL);
        relaxngschemas = xmlRelaxNGParse(ctxt);
        if (relaxngschemas == NULL) {
            xmlGenericError(xmlGenericErrorContext,
@@ -3611,10 +3596,7 @@ main(int argc, char **argv) {
            startTimer();
        }
        ctxt = xmlSchemaNewParserCtxt(schema);
-       xmlSchemaSetParserErrors(ctxt,
-               (xmlSchemaValidityErrorFunc) fprintf,
-               (xmlSchemaValidityWarningFunc) fprintf,
-               stderr);
+       xmlSchemaSetParserErrors(ctxt, xmlGenericError, xmlGenericError, NULL);
        wxschemas = xmlSchemaParse(ctxt);
        if (wxschemas == NULL) {
            xmlGenericError(xmlGenericErrorContext,