Fails to build with with GCC-14 (error: invalid conversion from ‘unsigned char*’ to ‘char*’ [-fpermissive])

[sebastic]

As reported in Debian Bug #1081301:

x86_64-linux-gnu-g++ -g -O2 -ffile-prefix-map=/build/aggdraw-1.3.18=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DVERSION=1.3.18 -DHAVE_FREETYPE2 -Iagg2/include -Iagg2/font_freetype -I/usr/include -I/usr/include/freetype -I/usr/include/freetype2 -I/usr/include/python3.12 -c agg2/font_freetype/agg_font_freetype.cpp -o build/temp.linux-x86_64-cpython-312/agg2/font_freetype/agg_font_freetype.o
agg2/font_freetype/agg_font_freetype.cpp: In member function 'void agg::font_engine_freetype_base::update_signature()':
agg2/font_freetype/agg_font_freetype.cpp:766:44: warning: format '%d' expects argument of type 'int', but argument 10 has type 'FT_Fixed' {aka 'long int'} [-Wformat=]
  766 |                     "%s,%u,%d,%d,%d:%dx%d,%d,%d,%d,%d,%d,%d,%08X",
      |                                           ~^
      |                                            |
      |                                            int
      |                                           %ld
......
  774 |                     m_matrix.xx,
      |                     ~~~~~~~~~~~             
      |                              |
      |                              FT_Fixed {aka long int}
agg2/font_freetype/agg_font_freetype.cpp:766:47: warning: format '%d' expects argument of type 'int', but argument 11 has type 'FT_Fixed' {aka 'long int'} [-Wformat=]
  766 |                     "%s,%u,%d,%d,%d:%dx%d,%d,%d,%d,%d,%d,%d,%08X",
      |                                              ~^
      |                                               |
      |                                               int
      |                                              %ld
......
  775 |                     m_matrix.xy,
      |                     ~~~~~~~~~~~                
      |                              |
      |                              FT_Fixed {aka long int}
agg2/font_freetype/agg_font_freetype.cpp:766:50: warning: format '%d' expects argument of type 'int', but argument 12 has type 'FT_Fixed' {aka 'long int'} [-Wformat=]
  766 |                     "%s,%u,%d,%d,%d:%dx%d,%d,%d,%d,%d,%d,%d,%08X",
      |                                                 ~^
      |                                                  |
      |                                                  int
      |                                                 %ld
......
  776 |                     m_matrix.yx,
      |                     ~~~~~~~~~~~                   
      |                              |
      |                              FT_Fixed {aka long int}
agg2/font_freetype/agg_font_freetype.cpp:766:53: warning: format '%d' expects argument of type 'int', but argument 13 has type 'FT_Fixed' {aka 'long int'} [-Wformat=]
  766 |                     "%s,%u,%d,%d,%d:%dx%d,%d,%d,%d,%d,%d,%d,%08X",
      |                                                    ~^
      |                                                     |
      |                                                     int
      |                                                    %ld
......
  777 |                     m_matrix.yy,
      |                     ~~~~~~~~~~~                      
      |                              |
      |                              FT_Fixed {aka long int}
agg2/font_freetype/agg_font_freetype.cpp: In instantiation of 'bool agg::decompose_ft_outline(const FT_Outline&, bool, PathStorage&, ConvCoord) [with PathStorage = path_storage_integer<int, 6>; ConvCoord = int (*)(int); FT_Outline = FT_Outline_]':
agg2/font_freetype/agg_font_freetype.cpp:883:48:   required from here
  883 |                         if(decompose_ft_outline(m_cur_face->glyph->outline,
      |                            ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
  884 |                                                 flip,
      |                                                 ~~~~~
  885 |                                                 m_path32,
      |                                                 ~~~~~~~~~
  886 |                                                 conv_coord_none))
      |                                                 ~~~~~~~~~~~~~~~~
agg2/font_freetype/agg_font_freetype.cpp:174:35: error: invalid conversion from 'unsigned char*' to 'char*' [-fpermissive]
  174 |             tags  = outline.tags  + first;
      |                     ~~~~~~~~~~~~~~^~~~~~~
      |                                   |
      |                                   unsigned char*
agg2/font_freetype/agg_font_freetype.cpp: In instantiation of 'bool agg::decompose_ft_outline(const FT_Outline&, bool, PathStorage&, ConvCoord) [with PathStorage = path_storage_integer<short int, 6>; ConvCoord = int (*)(int); FT_Outline = FT_Outline_]':
agg2/font_freetype/agg_font_freetype.cpp:903:48:   required from here
  903 |                         if(decompose_ft_outline(m_cur_face->glyph->outline,
      |                            ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
  904 |                                                 flip,
      |                                                 ~~~~~
  905 |                                                 m_path16,
      |                                                 ~~~~~~~~~
  906 |                                                 conv_coord_none))
      |                                                 ~~~~~~~~~~~~~~~~
agg2/font_freetype/agg_font_freetype.cpp:174:35: error: invalid conversion from 'unsigned char*' to 'char*' [-fpermissive]
  174 |             tags  = outline.tags  + first;
      |                     ~~~~~~~~~~~~~~^~~~~~~
      |                                   |
      |                                   unsigned char*
error: command '/usr/bin/x86_64-linux-gnu-g++' failed with exit code 1

ERROR Backend subprocess exited when trying to invoke build_wheel

[djhoese]

Yep, working on it in #100

[djhoese]

I've tried adding -fpermissive to the macos wheel builds as those are the only ones failing at the moment, but it doesn't seem to be allowing the build to continue. Any ideas what I'm missing to at least have a short term workaround for this incompatible vendored code?

[sebastic]

Appending -fpermissive to CXXFLAGS works for the Debian package build.

Others vendoring agg_font_freetype.cpp have encountered the same issue, see: r-lib/ragg#170 (comment) for their fix.

--- a/agg2/font_freetype/agg_font_freetype.cpp
+++ b/agg2/font_freetype/agg_font_freetype.cpp
@@ -171,7 +171,7 @@ namespace agg
             v_control = v_start;
 
             point = outline.points + first;
-            tags  = outline.tags  + first;
+            tags  = (char*)outline.tags  + first;
             tag   = FT_CURVE_TAG(tags[0]);
 
             // A contour cannot start with a cubic control point!

That change is also confirmed with the Debian package.

[djhoese]

Fixed in #100. Released as 1.3.19. Thanks for the bug report!