CI: switch to Debian 11 with GCC 11.

Also enable warnings as errors and GCC's static analyzer.

.cirrus.yml

@@ -25,10 +25,12 @@ task:
   matrix:
     - name: debian
       container:
-        image: gcc:8-buster
+        image: gcc:11-bullseye
       install_script: |
         apt-get update
         apt-get install -y libfuse-dev
+      env:
+        EXTRA_CFLAGS: -fanalyzer
 
     - name: macos
       macos_instance:
@@ -45,7 +47,7 @@ task:
 
   compile_script: |
     autoreconf --install
-    ./configure CFLAGS='-Wall -Wextra'
+    ./configure CFLAGS="-Wall -Wextra -Werror $EXTRA_CFLAGS"
     make -k
 
   test_script: |

libexfat/io.c

@@ -358,7 +358,7 @@ ssize_t exfat_read(struct exfat_dev* dev, void* buffer, size_t size)
 ssize_t exfat_write(struct exfat_dev* dev, const void* buffer, size_t size)
 {
 #ifdef USE_UBLIO
-	ssize_t result = ublio_pwrite(dev->ufh, buffer, size, dev->pos);
+	ssize_t result = ublio_pwrite(dev->ufh, (void*) buffer, size, dev->pos);
 	if (result >= 0)
 		dev->pos += size;
 	return result;
@@ -381,7 +381,7 @@ ssize_t exfat_pwrite(struct exfat_dev* dev, const void* buffer, size_t size,
 		off_t offset)
 {
 #ifdef USE_UBLIO
-	return ublio_pwrite(dev->ufh, buffer, size, offset);
+	return ublio_pwrite(dev->ufh, (void*) buffer, size, offset);
 #else
 	return pwrite(dev->fd, buffer, size, offset);
 #endif