Fix unannotated switch fallthroughs

Unfortunately, clang does not support doing this with comments, requiring yet
more preprocessor gunk.

3 files changed, 27 insertions, 8 deletions

diff --git a/src/n3.c b/src/n3.c
index fbe3c392..f56da170 100644
--- a/src/n3.c
+++ b/src/n3.c
@@ -30,6 +30,16 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if defined(__clang__) && __clang_major__ >= 10
+#  define SERD_FALLTHROUGH __attribute__((fallthrough))
+_Pragma("clang diagnostic push")
+_Pragma("clang diagnostic ignored \"-Wmissing-declarations\"")
+#elif defined(__GNUC__) && __GNUC__ >= 7
+#  define SERD_FALLTHROUGH __attribute__((fallthrough))
+#else
+#  define SERD_FALLTHROUGH
+#endif
+
 #define TRY(st, exp)      \
   do {                    \
     if (((st) = (exp))) { \
@@ -118,20 +128,20 @@ read_UCHAR(SerdReader* reader, Ref dest, uint32_t* char_code)
     buf[3] = (uint8_t)(0x80u | (c & 0x3Fu));
     c >>= 6;
     c |= (16 << 12); // set bit 4
-    /* fallthru */
+    SERD_FALLTHROUGH;
   case 3:
     buf[2] = (uint8_t)(0x80u | (c & 0x3Fu));
     c >>= 6;
     c |= (32 << 6); // set bit 5
-    /* fallthru */
+    SERD_FALLTHROUGH;
   case 2:
     buf[1] = (uint8_t)(0x80u | (c & 0x3Fu));
     c >>= 6;
     c |= 0xC0; // set bits 6 and 7
-    /* fallthru */
+    SERD_FALLTHROUGH;
   case 1:
     buf[0] = (uint8_t)c;
-    /* fallthru */
+    SERD_FALLTHROUGH;
   default:
     break;
   }
@@ -873,6 +883,7 @@ read_number(SerdReader* reader, Ref* dest, Ref* datatype, bool* ate_dot)
     case '+':
     case '-':
       push_byte(reader, *dest, eat_byte_safe(reader, c));
+      break;
     default:
       break;
     }
@@ -1718,3 +1729,7 @@ read_nquadsDoc(SerdReader* reader)
   }
   return SERD_SUCCESS;
 }
+
+#if defined(__clang__) && __clang_major__ >= 10
+_Pragma("clang diagnostic pop")
+#endif
diff --git a/src/string.c b/src/string.c
index b83ad58f..6c834cc4 100644
--- a/src/string.c
+++ b/src/string.c
@@ -66,6 +66,7 @@ serd_update_flags(const uint8_t c, SerdNodeFlags* const flags)
     break;
   case '"':
     *flags |= SERD_HAS_QUOTE;
+    break;
   default:
     break;
   }
@@ -120,16 +121,20 @@ static inline double
 read_sign(const char** sptr)
 {
   double sign = 1.0;
+
   switch (**sptr) {
   case '-':
     sign = -1.0;
-    // fallthru
+    ++(*sptr);
+    break;
   case '+':
     ++(*sptr);
-    // fallthru
+    break;
   default:
-    return sign;
+    break;
   }
+
+  return sign;
 }
 
 double
diff --git a/wscript b/wscript
index e6397cb9..1735b867 100644
--- a/wscript
+++ b/wscript
@@ -65,7 +65,6 @@ def configure(conf):
                 '-Wno-disabled-macro-expansion',
                 '-Wno-double-promotion',
                 '-Wno-format-nonliteral',
-                '-Wno-implicit-fallthrough',
                 '-Wno-nullability-extension',
                 '-Wno-nullable-to-nonnull-conversion',
                 '-Wno-padded',