Fix 'fall-through' warning messages.

Modern compilers get more insistent on that...

* include/freetype/internal/compiler-macros.h (FALL_THROUGH): Define.
* src/*: Use it instead of `/* fall through */` comments.

include/freetype/internal/compiler-macros.h

@@ -34,6 +34,19 @@ FT_BEGIN_HEADER
 #  if defined( _COMPILER_VERSION ) && ( _COMPILER_VERSION >= 730 )
 #    pragma set woff 3505
 #  endif
+#endif
+
+  /* Newer compilers warn for fall-through case statements. */
+#ifndef FALL_THROUGH
+#  if ( defined( __STDC_VERSION__ ) && __STDC_VERSION__ > 201710L ) || \
+      ( defined( __cplusplus ) && __cplusplus > 201402L )
+#    define FALL_THROUGH  [[__fallthrough__]]
+#  elif ( defined( __GNUC__ ) && __GNUC__ >= 7 )          || \
+        ( defined( __clang__ ) && __clang_major__ >= 10 )
+#    define FALL_THROUGH  __attribute__(( __fallthrough__ ))
+#  else
+#    define FALL_THROUGH  ( (void)0 )
+#  endif
 #endif
 
   /*

src/base/ftobjs.c

@@ -508,7 +508,7 @@
 
     case FT_PIXEL_MODE_LCD_V:
       height *= 3;
-      /* fall through */
+      FALL_THROUGH;
 
     case FT_PIXEL_MODE_GRAY:
     default:

src/lzw/ftzopen.c

@@ -315,7 +315,7 @@
 
         state->phase = FT_LZW_PHASE_CODE;
       }
-      /* fall-through */
+      FALL_THROUGH;
 
     case FT_LZW_PHASE_CODE:
       {
@@ -373,7 +373,7 @@
 
         state->phase = FT_LZW_PHASE_STACK;
       }
-      /* fall-through */
+      FALL_THROUGH;
 
     case FT_LZW_PHASE_STACK:
       {

src/psaux/afmparse.c

@@ -1061,7 +1061,7 @@
         if ( error )
           goto Fail;
         /* we only support kern data, so ... */
-        /* fall through                      */
+        FALL_THROUGH;
 
       case AFM_TOKEN_ENDFONTMETRICS:
         return FT_Err_Ok;

src/sdf/ftsdf.c

@@ -871,7 +871,7 @@
       cbox.yMax = edge.control_b.y;
 
       is_set = 1;
-      /* fall through */
+      FALL_THROUGH;
 
     case SDF_EDGE_CONIC:
       if ( is_set )
@@ -899,7 +899,7 @@
 
         is_set = 1;
       }
-      /* fall through */
+      FALL_THROUGH;
 
     case SDF_EDGE_LINE:
       if ( is_set )

src/sfnt/pngshim.c

@@ -407,7 +407,8 @@
     switch ( color_type )
     {
     default:
-      /* Shouldn't happen, but fall through. */
+      /* Shouldn't happen, but ... */
+      FALL_THROUGH;
 
     case PNG_COLOR_TYPE_RGB_ALPHA:
       png_set_read_user_transform_fn( png, premultiply_data );

src/sfnt/sfdriver.c

@@ -378,61 +378,61 @@
       {
       case 15:
         k4 ^= (FT_UInt32)tail[14] << 16;
-        /* fall through */
+        FALL_THROUGH;
       case 14:
         k4 ^= (FT_UInt32)tail[13] << 8;
-        /* fall through */
+        FALL_THROUGH;
       case 13:
         k4 ^= (FT_UInt32)tail[12];
         k4 *= c4;
         k4  = ROTL32( k4, 18 );
         k4 *= c1;
         h4 ^= k4;
-        /* fall through */
+        FALL_THROUGH;
 
       case 12:
         k3 ^= (FT_UInt32)tail[11] << 24;
-        /* fall through */
+        FALL_THROUGH;
       case 11:
         k3 ^= (FT_UInt32)tail[10] << 16;
-        /* fall through */
+        FALL_THROUGH;
       case 10:
         k3 ^= (FT_UInt32)tail[9] << 8;
-        /* fall through */
+        FALL_THROUGH;
       case 9:
         k3 ^= (FT_UInt32)tail[8];
         k3 *= c3;
         k3  = ROTL32( k3, 17 );
         k3 *= c4;
         h3 ^= k3;
-        /* fall through */
+        FALL_THROUGH;
 
       case 8:
         k2 ^= (FT_UInt32)tail[7] << 24;
-        /* fall through */
+        FALL_THROUGH;
       case 7:
         k2 ^= (FT_UInt32)tail[6] << 16;
-        /* fall through */
+        FALL_THROUGH;
       case 6:
         k2 ^= (FT_UInt32)tail[5] << 8;
-        /* fall through */
+        FALL_THROUGH;
       case 5:
         k2 ^= (FT_UInt32)tail[4];
         k2 *= c2;
         k2  = ROTL32( k2, 16 );
         k2 *= c3;
         h2 ^= k2;
-        /* fall through */
+        FALL_THROUGH;
 
       case 4:
         k1 ^= (FT_UInt32)tail[3] << 24;
-        /* fall through */
+        FALL_THROUGH;
       case 3:
         k1 ^= (FT_UInt32)tail[2] << 16;
-        /* fall through */
+        FALL_THROUGH;
       case 2:
         k1 ^= (FT_UInt32)tail[1] << 8;
-        /* fall through */
+        FALL_THROUGH;
       case 1:
         k1 ^= (FT_UInt32)tail[0];
         k1 *= c1;

src/sfnt/ttsbit.c

@@ -1193,7 +1193,7 @@
           goto Fail;
 
         p += 1;  /* skip padding */
-        /* fall-through */
+        FALL_THROUGH;
 
       case 9:
         loader = tt_sbit_decoder_load_compound;

src/smooth/ftgrays.c

@@ -418,21 +418,21 @@ typedef ptrdiff_t  FT_PtrDist;
 
   /* It is faster to write small spans byte-by-byte than calling     */
   /* `memset'.  This is mainly due to the cost of the function call. */
-#define FT_GRAY_SET( d, s, count )                          \
-  FT_BEGIN_STMNT                                            \
-    unsigned char* q = d;                                   \
-    switch ( count )                                        \
-    {                                                       \
-      case 7: *q++ = (unsigned char)s; /* fall through */   \
-      case 6: *q++ = (unsigned char)s; /* fall through */   \
-      case 5: *q++ = (unsigned char)s; /* fall through */   \
-      case 4: *q++ = (unsigned char)s; /* fall through */   \
-      case 3: *q++ = (unsigned char)s; /* fall through */   \
-      case 2: *q++ = (unsigned char)s; /* fall through */   \
-      case 1: *q   = (unsigned char)s; /* fall through */   \
-      case 0: break;                                        \
-      default: FT_MEM_SET( d, s, count );                   \
-    }                                                       \
+#define FT_GRAY_SET( d, s, count )                   \
+  FT_BEGIN_STMNT                                     \
+    unsigned char* q = d;                            \
+    switch ( count )                                 \
+    {                                                \
+      case 7: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 6: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 5: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 4: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 3: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 2: *q++ = (unsigned char)s; FALL_THROUGH; \
+      case 1: *q   = (unsigned char)s; FALL_THROUGH; \
+      case 0: break;                                 \
+      default: FT_MEM_SET( d, s, count );            \
+    }                                                \
   FT_END_STMNT
 
 

src/type42/t42parse.c

@@ -733,7 +733,7 @@
                               ttf_reserved ) )
               goto Fail;
           }
-          /* fall through */
+          FALL_THROUGH;
 
         case BEFORE_TABLE_DIR:
           /* the offset table is read; read the table directory */
@@ -785,7 +785,7 @@
                               ttf_reserved ) )
               goto Fail;
           }
-          /* fall through */
+          FALL_THROUGH;
 
         case OTHER_TABLES:
           /* all other tables are just copied */