Fix etags for Ruby module definitions with ::

Problem: In Ruby we can define a nested module/class the safe
way (in the sense, if the parent module does not exist, it will
define it:

  module M
    module N
    end
  end

If M already exists, we can also write:

  module M::N; end

With the later notation, the tag generated by etags will be M::N.
When browsing the code, using xref-find-definitions when the point
is on N, will not be able to find the definition of N because the
implicit tag name is M::N.

This is the same problem with nested classes or even some rare
allowed definitions like explicitely defining a module/class from
the global namespace:

  class ::A; end

Solution: We need to give an explicit tag name.  To achieve this,
on module/class definition we truncate the name to the last found
column.
* lib-src/etags.c (Ruby_functions): Support "::" in module
definitions.
* test/manual/etags/README: Update instructions.
* test/manual/etags/ruby-src/test1.ru: Add identifiers with "::".
* test/manual/etags/CTAGS.good:
* test/manual/etags/CTAGS.good_crlf:
* test/manual/etags/CTAGS.good_update:
* test/manual/etags/ETAGS.good_1:
* test/manual/etags/ETAGS.good_2:
* test/manual/etags/ETAGS.good_3:
* test/manual/etags/ETAGS.good_4:
* test/manual/etags/ETAGS.good_5:
* test/manual/etags/ETAGS.good_6:
* test/manual/etags/ETAGS.good_7: Adapt expected results to the
change.  (Bug#77421)

Copyright-paperwork-exempt: yes

lib-src/etags.c

@@ -5069,7 +5069,10 @@ Ruby_functions (FILE *inf)
 	 /* Ruby method names can end in a '='.  Also, operator overloading can
 	    define operators whose names include '='.  */
 	  while (!notinname (*cp) || *cp == '=')
-	    cp++;
+	    {
+	      cp++;
+	      if (*(cp - 1) == ':') name = cp;
+	    }
 
 	  /* Remove "self." from the method name.  */
 	  if (cp - name > self_size1

test/manual/etags/CTAGS.good

@@ -327,6 +327,7 @@ ButtonBar	pyt-src/server.py	/^def ButtonBar(frame, legend, ref, alternatives, co
 C	cp-src/fail.C	9
 C	cp-src/fail.C	/^			   C(int i) {x = i;}$/
 C	cp-src/fail.C	25
+C	ruby-src/test1.ru	/^class A::C; end$/
 CALLMANY	c-src/emacs/src/lisp.h	/^#define CALLMANY(f, array) (f) (ARRAYELTS (array),/
 CALLN	c-src/emacs/src/lisp.h	/^#define CALLN(f, ...) CALLMANY (f, ((Lisp_Object [/
 CAR	c-src/emacs/src/lisp.h	/^CAR (Lisp_Object c)$/
@@ -483,6 +484,7 @@ Cstar_suffixes	c-src/etags.c	562
 Cube.data.getFoo	lua-src/test.lua	/^function Cube.data.getFoo ()$/
 D	cp-src/fail.C	41
 D	cp-src/fail.C	/^		D() : ::A::T2::T(97), x(1066) {}$/
+D	ruby-src/test1.ru	/^class ::D; end$/
 DAEMON_RUNNING	c-src/emacs/src/lisp.h	4258
 DAEMON_RUNNING	c-src/emacs/src/lisp.h	4262
 DARKGRAY	cp-src/screen.hpp	20
@@ -964,6 +966,7 @@ LowerCaseNmStr	pas-src/common.pas	/^function LowerCaseNmStr; (*($/
 Lua_functions	c-src/etags.c	/^Lua_functions (FILE *inf)$/
 Lua_help	c-src/etags.c	600
 Lua_suffixes	c-src/etags.c	598
+M	ruby-src/test1.ru	/^module A::M; end$/
 MAGENTA	cp-src/screen.hpp	17
 MAGICBYTE	c-src/emacs/src/gmalloc.c	1861
 MAGICFREE	c-src/emacs/src/gmalloc.c	1860

test/manual/etags/ETAGS.good_1

@@ -3103,7 +3103,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -3133,6 +3133,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_2

@@ -3676,7 +3676,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -3706,6 +3706,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_3

@@ -3510,7 +3510,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -3540,6 +3540,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_4

@@ -3265,7 +3265,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -3295,6 +3295,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_5

@@ -4245,7 +4245,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -4275,6 +4275,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_6

@@ -4245,7 +4245,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -4275,6 +4275,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/ETAGS.good_7

@@ -3085,7 +3085,7 @@ module ModuleExample1,0
     def module_instance_method46,1051
     def ModuleExample.module_class_methodmodule_class_method
49,1131
 
-ruby-src/test1.ru,935
+ruby-src/test1.ru,998
 class A1,0
  def a(2,8
  def b(5,38
@@ -3115,6 +3115,9 @@ module A9,57
                 :qux1)qux1
36,563
     alias_method ( :foo2,foo2
37,586
 A::Constant Constant
42,655
+class A::C;C
47,700
+module A::M;M
48,716
+class ::D;D
49,733
 
 rs-src/test.rs,52
 enum IpAddrKind 3,11

test/manual/etags/README

@@ -5,9 +5,9 @@ The input files, which include source files in various languages
 supported by the programs, are in the *-src/ directories (e.g., c-src
 for C sources, ada-src for Ada, tex-src for TeX, etc.).
 
-The expected results are slightly different for each of the 7 commands
+The expected results are slightly different for each of the 8 commands
 (see below) run by the test suite, and are on files ETAGS.good_N
-(where N is between 1 and 6) and CTAGS.good.
+(where N is between 1 and 7) and CTAGS.good.
 
 To run the tests, say
 
@@ -48,9 +48,13 @@ corresponding "good" files, one by one.  Like this:
   $ cp ETAGS ETAGS.good_3
   ...
   $ make check
-  $ cp ETAGS ETAGS.good_6
+  $ cp ETAGS ETAGS.good_7
   $ make check
   $ cp CTAGS CTAGS.good
+  $ make check
+  $ cp CTAGS CTAGS.good_update
+  $ make check
+  $ cp CTAGS CTAGS.good_crlf
 
 This uses the fact that "make check" will stop after the first
 failure, i.e. after the first time 'diff' reports any diffs, and then

test/manual/etags/ruby-src/test1.ru

@@ -43,3 +43,7 @@ A::Constant = 5
 
 # def foo_in_comment
 # end
+
+class A::C; end
+module A::M; end
+class ::D; end