vmod function/method name clash

[nigoroll]

As demonstrated with this patch

diff --git a/vmod/vmod_debug.vcc b/vmod/vmod_debug.vcc
index df8ba6247..310a046bb 100644
--- a/vmod/vmod_debug.vcc
+++ b/vmod/vmod_debug.vcc
@@ -69,6 +69,8 @@ $Function STRING test_priv_top(PRIV_TOP, STRING)
 
 Test function for TOP private pointers
 
+$Function VOID obj_enum(ENUM { phk, des, kristian, mithrandir, martin })
+
 $Object obj(STRING string="default", ENUM { one, two, three } number=one)
 
 Test object

we do not support a function called obj.name with a method name for class obj.

Compiler error:

/usr/local/bin/python3.10 ../lib/libvcc/vmodtool.py --boilerplate -o vcc_debug_if ./vmod_debug.vcc
WARNING: Not emitting .RST for $Event event_function

WARNING: Not emitting .RST for $Event event_function

  CC       libvmod_debug_la-vcc_debug_if.lo
In file included from vcc_debug_if.c:10:
./vcc_debug_if.h:94:10: error: conflicting types for 'xyzzy_obj_enum'
VCL_VOID xyzzy_obj_enum(VRT_CTX, struct VPFX(debug_obj) *,
         ^
./vcc_debug_if.h:89:10: note: previous declaration is here
VCL_VOID xyzzy_obj_enum(VRT_CTX, VCL_ENUM);
         ^
vcc_debug_if.c:128:18: error: typedef redefinition with different types ('VCL_VOID (const struct vrt_ctx *, VCL_ENUM)' (aka 'void (const struct vrt_ctx *, const char *)') vs 'VCL_VOID (const struct vrt_ctx *, struct xyzzy_debug_obj *, VCL_ENUM)' (aka 'void (const struct vrt_ctx *, struct xyzzy_debug_obj *, const char *)'))
typedef VCL_VOID td_xyzzy_debug_obj_enum(VRT_CTX, VCL_ENUM);
                 ^
vcc_debug_if.c:32:18: note: previous definition is here
typedef VCL_VOID td_xyzzy_debug_obj_enum(VRT_CTX,
                 ^
vcc_debug_if.c:201:28: error: duplicate member 'obj_enum'
        td_xyzzy_debug_obj_enum         *obj_enum;
                                         ^
vcc_debug_if.c:198:28: note: previous declaration is here
        td_xyzzy_debug_obj_enum         *obj_enum;
                                         ^
3 errors generated.
make: *** [Makefile:1154: libvmod_debug_la-vcc_debug_if.lo] Error 1

suggestion: rename methods to obj__method (two underscores) and blacklist underscore as prefix/suffix for object/method/function names.

[dridi]

After looking into this, I think the suggested extra underscore should work on principle. Valid VCL symbols can't start with an underscore, so VMOD symbols can't either. See VCT_invalid_name() in varnishd and "Illegal name" in vmodtool.

[nigoroll]

Options discussed during bugwash:

• have vmodtool detect the clash and use the double underscore only if a clash exists.
  • Expand VPFX() into VPFX_FUNCTION() and VPFX_METHOD()
    • do not want macro proliferation
  • have $Prefix_function and $Prefix_method in the vcc file
• enable overriding the default cname as in $Function VOID obj_enum(ENUM { phk, des, kristian, mithrandir, martin }) $cname=obj__enum

I will play with it...

[nigoroll]

Because this had not been mentioned here: Now that #4240 reached the scene, my new proposal is to solve this issue by the same method: The option to specify the c name of the function/method similar to the $cname=obj__enum proposal before, but using the vcc_name:cname syntax