make: Fix coverage target when using lcov 2.0 (cowsql#119)

The lcov 2.0 release has some backward-incompatible changes, make it
ignore warnings for now.

Makefile.am

@@ -278,6 +278,9 @@ include $(top_srcdir)/aminclude_static.am
 CODE_COVERAGE_DIRECTORY=./src
 CODE_COVERAGE_OUTPUT_DIRECTORY=coverage
 CODE_COVERAGE_OUTPUT_FILE=coverage.info
+if LCOV_VERSION_2
+CODE_COVERAGE_LCOV_SHOPTS_DEFAULT=--ignore-errors unused
+endif
 CODE_COVERAGE_IGNORE_PATTERN="/usr/include/*"
 CODE_COVERAGE_BRANCH_COVERAGE=1
 CODE_COVERAGE_LCOV_OPTIONS=$(CODE_COVERAGE_LCOV_OPTIONS_DEFAULT) --rc lcov_excl_br_line="assert\("

configure.ac

@@ -67,6 +67,14 @@ AM_CONDITIONAL(SANITIZE_ENABLED, test x"$enable_sanitize" = x"yes")
 # Whether to enable code coverage.
 AX_CODE_COVERAGE
 
+# Check if lcov >= 2.0
+AS_IF([test x"$enable_code_coverage" = xyes],
+      [AX_COMPARE_VERSION($(lcov --version|cut -f 4 -d " " | cut -f 1 -d -), [ge], [2.0],
+          [have_lcov_2=yes], [have_lcov_2=no])
+      ],
+      [have_lcov_2=no])
+AM_CONDITIONAL(LCOV_VERSION_2, test x"$have_lcov_2" = x"yes")
+
 # Checks for header files.
 AC_CHECK_HEADERS([stdlib.h string.h stdio.h assert.h unistd.h linux/io_uring.h linux/aio_abi.h])
 

src/raft.c

@@ -418,6 +418,7 @@ int raft_step(struct raft *r,
               struct raft_event *event,
               struct raft_update *update)
 {
+    const char *state_name;
     int rv;
 
     assert(event != NULL);
@@ -478,7 +479,8 @@ int raft_step(struct raft *r,
                                      event->snapshot.trailing);
             break;
         case RAFT_TIMEOUT:
-            infof("timeout as %s", raft_state_name(r->state));
+            state_name = raft_state_name(r->state);
+            infof("timeout as %s", state_name);
             rv = Tick(r);
             break;
         case RAFT_SUBMIT:

src/uv_snapshot.c

@@ -137,13 +137,17 @@ static int uvSnapshotIsOrphanInternal(const char *dir,
                                       bool meta,
                                       bool *orphan)
 {
-    int rv;
-    *orphan = false;
-
     raft_term term;
     raft_index index;
     raft_time timestamp;
-    if (!uvSnapshotParseFilename(filename, meta, &term, &index, &timestamp)) {
+    bool is_snapshot_filename;
+    int rv;
+
+    *orphan = false;
+
+    is_snapshot_filename =
+        uvSnapshotParseFilename(filename, meta, &term, &index, &timestamp);
+    if (!is_snapshot_filename) {
         return 0;
     }