[ft-devel] Strict compiler warns at gxvmort2.c

[Antoine Leca]

Hi Toshiya-san,

Microsoft's compiler bails out while compiling src/gxvalid/gxvalid.c
cl /Za /D_CRT_SECURE_NO_DEPRECATE  /Iobjs /I..\freetype2\builds\win32
/I..\freetype2\include /nologo /c /Ox /W3 /WX /DFT2_BUILD_LIBRARY
/DFT_CONFIG_MODULES_H="<ftmodule.h>"  /I..\freetype2\src\gxvalid
/Foobjs\gxvalid.obj ..\freetype2\src\gxvalid\gxvalid.c
gxvalid.c
C:\Users\FT\freetype2\src\gxvalid\gxvmort2.c(195) : error C2220: warning
treated as error - no object file generated
C:\Users\FT\freetype2\src\gxvalid\gxvmort2.c(195) : warning C4018: '>' :
signed/unsigned mismatch
mingw32-make.exe: *** [objs/gxvalid.obj] Error 2

A quick look shows this is caused by the combination of
  typedef struct  GXV_mort_subtable_type2_StateOptRec_
  { /* ... */
    FT_UShort  ligatureTable;
    FT_UShort  ligActionTable_length;

and the actual code
      FT_ULong   offset;
    /* ... */
      } else if ( offset * 2 >
                  optdata->ligatureTable + optdata->ligatureTable_length )

The warning is pretty strict but highlights a potential problem on a
16-bit target (the sum can overflow, so being a very big negative, which
will trigger the test in a wrong way.)

I added a cast (to FT_ULong) to avoid the problem.

While I was here, I fixed a number of issues with the printf
specifications in the same area of code; I am not sure this is really
needed since I guess there are a lot of similar mismatches through the
codebase (any comments this about?)


Antoine

diff --git a/src/gxvalid/gxvmort2.c b/src/gxvalid/gxvmort2.c
index 9e08fb7..41bbd7f 100644
--- a/src/gxvalid/gxvmort2.c
+++ b/src/gxvalid/gxvmort2.c
@@ -186,20 +186,23 @@
       offset = lig_action & 0x3FFFFFFFUL;
       if ( offset * 2 < optdata->ligatureTable )
       {
-        GXV_TRACE(( "too short offset 0x%08x:"
-                    " 2 x offset < ligatureTable (%d byte rewind)\n",
-                     offset, optdata->ligatureTable - offset * 2 ));
+        GXV_TRACE(( "too short offset 0x%08lx:"
+                    " 2 x offset < ligatureTable (%ld byte rewind)\n",
+                     (unsigned long)offset,
+                     optdata->ligatureTable - (long)offset * 2 ));
 
         GXV_SET_ERR_IF_PARANOID( FT_INVALID_OFFSET );
       } else if ( offset * 2 >
-                  optdata->ligatureTable + optdata->ligatureTable_length )
+                  (FT_ULong)optdata->ligatureTable +
+                  optdata->ligatureTable_length )
       {
-        GXV_TRACE(( "too long offset 0x%08x:"
+        GXV_TRACE(( "too long offset 0x%08lx:"
                     " 2 x offset > ligatureTable + ligatureTable_length"
-                    " (%d byte overrun)\n",
-                     offset,
-                     optdata->ligatureTable + optdata->ligatureTable_length
-                     - offset * 2 ));
+                    " (%ld byte overrun)\n",
+                     (unsigned long)offset,
+                     (long)optdata->ligatureTable
+                     + optdata->ligatureTable_length
+                     - (long)offset * 2 ));
 
         GXV_SET_ERR_IF_PARANOID( FT_INVALID_OFFSET );
       }