Breakpoints in symbols with ABI tags (PR c++/19436)

Trying to set a breakpoint in a function with an ABI tag does not work
currently.  E.g., debugging gdb itself, we see this with the
"string_printf" function:

 (top-gdb) b string_print                               [TAB]
 (top-gdb) b string_printf[abi:cxx11](char const*, ...) [RET]
 No source file named string_printf[abi.
 Make breakpoint pending on future shared library load? (y or [n])

Quoting doesn't help:
 (top-gdb) b 'string_printf[abi:cxx11]'(char const*, ...)
 malformed linespec error: unexpected string, "(char const*, ...)"
 (top-gdb) b 'string_printf[abi:cxx11](char const*, ...)'
 No source file named string_printf[abi.
 Make breakpoint pending on future shared library load? (y or [n]) n

This patch fixes this, and takes it a bit further.

The actual symbol name as demangled by libiberty's demangler is really

 string_printf[abi:cxx11](char const*, ...)

however, this patch makes it possible to set the breakpoint with

 string_printf(char const*, ...)

too.  I.e., ignoring the ABI tag.

And to match, it teaches the completer to complete the symbol name
without the ABI tag, i.e.,

  "string_pri<TAB>"  -> "string_printf(char const*, ...)"

If however, you really want to break on a symbol with the tag, then
you simply start writing the tag, and GDB will preserve it, like:

  "string_printf[a<TAB>"  -> "string_printf[abi:cxx11](char const*, ...)"

Grows the gdb.linespec/ tests like this:

  -# of expected passes           8977
  +# of expected passes           9176

gdb/ChangeLog:
2017-11-29  Pedro Alves  <palves@redhat.com>

	PR c++/19436
	* NEWS: Mention setting breakpoints on functions with C++ ABI
	tags.
	* completer.h (completion_match_for_lcd) <match,
	mark_ignored_range>: New methods.
	<finish>: Consider ignored ranges.
	<clear>: Clear ignored ranges.
	<m_ignored_ranges, m_finished_storage>: New fields.
	* cp-support.c (cp_search_name_hash): Ignore ABI tags.
	(cp_symbol_name_matches_1, cp_fq_symbol_name_matches): Pass the
	completion_match_for_lcd pointer to strncmp_iw_with_mode.
	(test_cp_symbol_name_cmp): Add [abi:...] tags unit tests.
	* language.c (default_symbol_name_matcher): Pass the
	completion_match_for_lcd pointer to strncmp_iw_with_mode.
	* linespec.c (linespec_lexer_lex_string): Don't tokenize ABI tags.
	* utils.c (skip_abi_tag): New function.
	(strncmp_iw_with_mode): Add completion_match_for_lcd parameter.
	Handle ABI tags.
	* utils.h (strncmp_iw_with_mode): Add completion_match_for_lcd
	parameter.

gdb/testsuite/ChangeLog:
2017-11-29  Pedro Alves  <palves@redhat.com>

	PR c++/19436
	* gdb.linespec/cpls-abi-tag.cc: New file.
	* gdb.linespec/cpls-abi-tag.exp: New file.

gdb/doc/ChangeLog:
2017-11-29  Pedro Alves  <palves@redhat.com>

	PR c++/19436
	* gdb.texinfo (Debugging C Plus Plus): Document setting
	breakpoints in functions with ABI tags.

1 files changed, 94 insertions, 2 deletions

diff --git a/gdb/utils.c b/gdb/utils.c
index 3e817ed..98ef6ac 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -2247,12 +2247,40 @@ cp_is_operator (const char *string, const char *start)
 	  && !valid_identifier_name_char (string[CP_OPERATOR_LEN]));
 }
 
+/* If *NAME points at an ABI tag, skip it and return true.  Otherwise
+   leave *NAME unmodified and return false.  (see GCC's abi_tag
+   attribute), such names are demangled as e.g.,
+   "function[abi:cxx11]()".  */
+
+static bool
+skip_abi_tag (const char **name)
+{
+  const char *p = *name;
+
+  if (startswith (p, "[abi:"))
+    {
+      p += 5;
+
+      while (valid_identifier_name_char (*p))
+	p++;
+
+      if (*p == ']')
+	{
+	  p++;
+	  *name = p;
+	  return true;
+	}
+    }
+  return false;
+}
+
 /* See utils.h.  */
 
 int
 strncmp_iw_with_mode (const char *string1, const char *string2,
 		      size_t string2_len, strncmp_iw_mode mode,
-		      enum language language)
+		      enum language language,
+		      completion_match_for_lcd *match_for_lcd)
 {
   const char *string1_start = string1;
   const char *end_str2 = string2 + string2_len;
@@ -2271,6 +2299,37 @@ strncmp_iw_with_mode (const char *string1, const char *string2,
 	  skip_spaces = false;
 	}
 
+      /* Skip [abi:cxx11] tags in the symbol name if the lookup name
+	 doesn't include them.  E.g.:
+
+	 string1: function[abi:cxx1](int)
+	 string2: function
+
+	 string1: function[abi:cxx1](int)
+	 string2: function(int)
+
+	 string1: Struct[abi:cxx1]::function()
+	 string2: Struct::function()
+
+	 string1: function(Struct[abi:cxx1], int)
+	 string2: function(Struct, int)
+      */
+      if (string2 == end_str2
+	  || (*string2 != '[' && !valid_identifier_name_char (*string2)))
+	{
+	  const char *abi_start = string1;
+
+	  /* There can be more than one tag.  */
+	  while (*string1 == '[' && skip_abi_tag (&string1))
+	    ;
+
+	  if (match_for_lcd != NULL && abi_start != string1)
+	    match_for_lcd->mark_ignored_range (abi_start, string1);
+
+	  while (isspace (*string1))
+	    string1++;
+	}
+
       if (*string1 == '\0' || string2 == end_str2)
 	break;
 
@@ -2405,7 +2464,40 @@ strncmp_iw_with_mode (const char *string1, const char *string2,
   if (string2 == end_str2)
     {
       if (mode == strncmp_iw_mode::NORMAL)
-	return 0;
+	{
+	  /* Strip abi tag markers from the matched symbol name.
+	     Usually the ABI marker will be found on function name
+	     (automatically added because the function returns an
+	     object marked with an ABI tag).  However, it's also
+	     possible to see a marker in one of the function
+	     parameters, for example.
+
+	     string2 (lookup name):
+	       func
+	     symbol name:
+	       function(some_struct[abi:cxx11], int)
+
+	     and for completion LCD computation we want to say that
+	     the match was for:
+	       function(some_struct, int)
+	  */
+	  if (match_for_lcd != NULL)
+	    {
+	      while ((string1 = strstr (string1, "[abi:")) != NULL)
+		{
+		  const char *abi_start = string1;
+
+		  /* There can be more than one tag.  */
+		  while (skip_abi_tag (&string1) && *string1 == '[')
+		    ;
+
+		  if (abi_start != string1)
+		    match_for_lcd->mark_ignored_range (abi_start, string1);
+		}
+	    }
+
+	  return 0;
+	}
       else
 	return (*string1 != '\0' && *string1 != '(');
     }