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.

13 files changed, 721 insertions, 18 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d65337a..567cc00 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,51 @@
 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.
+
+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.
+
+2017-11-29  Pedro Alves  <palves@redhat.com>
+
 	* NEWS: Mention that breakpoints on C++ functions are now set on
 	on all namespaces/classes by default, and mention "break
 	-qualified".
diff --git a/gdb/NEWS b/gdb/NEWS
index 984fd96..06df528 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -72,6 +72,28 @@
   program, the "break -q B::func" command sets a breakpoint on
   "B::func", only.
 
+* Breakpoints on functions marked with C++ ABI tags
+
+  GDB can now set breakpoints on functions marked with C++ ABI tags
+  (e.g., [abi:cxx11]).  See here for a description of ABI tags:
+  https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/
+
+  Functions with a C++11 abi tag are demangled/displayed like this:
+
+    function[abi:cxx11](int)
+            ^^^^^^^^^^^
+
+  You can now set a breakpoint on such functions simply as if they had
+  no tag, like:
+
+    (gdb) b function(int)
+
+  Or if you need to disambiguate between tags, like:
+
+    (gdb) b function[abi:other_tag](int)
+
+  Tab completion was adjusted accordingly as well.
+
 * Python Scripting
 
   ** New events gdb.new_inferior, gdb.inferior_deleted, and
diff --git a/gdb/completer.h b/gdb/completer.h
index f756412..9ce70bf 100644
--- a/gdb/completer.h
+++ b/gdb/completer.h
@@ -122,28 +122,82 @@ private:
    "b push_ba" on a C++ program usually completes to
    std::vector<...>::push_back, std::string::push_back etc.  In such
    case, the symbol comparison routine will set the LCD match to point
-   into the "push_back" substring within the symbol's name string.  */
+   into the "push_back" substring within the symbol's name string.
+   Also, in some cases, the symbol comparison routine will want to
+   ignore parts of the symbol name for LCD purposes, such as for
+   example symbols with abi tags in C++.  In such cases, the symbol
+   comparison routine will set MARK_IGNORED_RANGE to mark the ignored
+   substrings of the matched string.  The resulting LCD string with
+   the ignored parts stripped out is computed at the end of a
+   completion match sequence iff we had a positive match.  */
 
 class completion_match_for_lcd
 {
 public:
+  /* Get the resulting LCD, after a successful match.  */
+  const char *match ()
+  { return m_match; }
+
   /* Set the match for LCD.  See m_match's description.  */
   void set_match (const char *match)
   { m_match = match; }
 
-  /* Get the resulting LCD, after a successful match.  */
+  /* Mark the range between [BEGIN, END) as ignored.  */
+  void mark_ignored_range (const char *begin, const char *end)
+  { m_ignored_ranges.emplace_back (begin, end); }
+
+  /* Get the resulting LCD, after a successful match.  If there are
+     ignored ranges, then this builds a new string with the ignored
+     parts removed (and stores it internally).  As such, the result of
+     this call is only good for the current completion match
+     sequence.  */
   const char *finish ()
-  { return m_match; }
+  {
+    if (m_ignored_ranges.empty ())
+      return m_match;
+    else
+      {
+	m_finished_storage.clear ();
+
+	const char *prev = m_match;
+	for (const auto &range : m_ignored_ranges)
+	  {
+	    m_finished_storage.append (prev, range.first);
+	    prev = range.second;
+	  }
+	m_finished_storage.append (prev);
+
+	return m_finished_storage.c_str ();
+      }
+  }
 
   /* Prepare for another completion matching sequence.  */
   void clear ()
-  { m_match = NULL; }
+  {
+    m_match = NULL;
+    m_ignored_ranges.clear ();
+  }
 
 private:
   /* The completion match result for LCD.  This is usually either a
      pointer into to a substring within a symbol's name, or to the
      storage of the pairing completion_match object.  */
   const char *m_match;
+
+  /* The ignored substring ranges within M_MATCH.  E.g., if we were
+     looking for completion matches for C++ functions starting with
+       "functio"
+     and successfully match:
+       "function[abi:cxx11](int)"
+     the ignored ranges vector will contain an entry that delimits the
+     "[abi:cxx11]" substring, such that calling finish() results in:
+       "function(int)"
+   */
+  std::vector<std::pair<const char *, const char *>> m_ignored_ranges;
+
+  /* Storage used by the finish() method, if it has to compute a new
+     string.  */
+  std::string m_finished_storage;
 };
 
 /* Convenience aggregate holding info returned by the symbol name
diff --git a/gdb/cp-support.c b/gdb/cp-support.c
index 172d821..34a8439 100644
--- a/gdb/cp-support.c
+++ b/gdb/cp-support.c
@@ -1629,7 +1629,23 @@ cp_search_name_hash (const char *search_name)
   if (prefix_len != 0)
     search_name += prefix_len + 2;
 
-  return default_search_name_hash (search_name);
+  unsigned int hash = 0;
+  for (const char *string = search_name; *string != '\0'; ++string)
+    {
+      string = skip_spaces (string);
+
+      if (*string == '(')
+	break;
+
+      /* Ignore ABI tags such as "[abi:cxx11].  */
+      if (*string == '['
+	  && startswith (string + 1, "abi:")
+	  && string[5] != ':')
+	break;
+
+      hash = SYMBOL_HASH_NEXT (hash, *string);
+    }
+  return hash;
 }
 
 /* Helper for cp_symbol_name_matches (i.e., symbol_name_matcher_ftype
@@ -1674,11 +1690,13 @@ cp_symbol_name_matches_1 (const char *symbol_search_name,
 			  completion_match_result *comp_match_res)
 {
   const char *sname = symbol_search_name;
+  completion_match_for_lcd *match_for_lcd
+    = (comp_match_res != NULL ? &comp_match_res->match_for_lcd : NULL);
 
   while (true)
     {
       if (strncmp_iw_with_mode (sname, lookup_name, lookup_name_len,
-				mode, language_cplus) == 0)
+				mode, language_cplus, match_for_lcd) == 0)
 	{
 	  if (comp_match_res != NULL)
 	    {
@@ -1728,14 +1746,15 @@ cp_fq_symbol_name_matches (const char *symbol_search_name,
 {
   /* Get the demangled name.  */
   const std::string &name = lookup_name.cplus ().lookup_name ();
-
+  completion_match_for_lcd *match_for_lcd
+    = (comp_match_res != NULL ? &comp_match_res->match_for_lcd : NULL);
   strncmp_iw_mode mode = (lookup_name.completion_mode ()
 			  ? strncmp_iw_mode::NORMAL
 			  : strncmp_iw_mode::MATCH_PARAMS);
 
   if (strncmp_iw_with_mode (symbol_search_name,
 			    name.c_str (), name.size (),
-			    mode, language_cplus) == 0)
+			    mode, language_cplus, match_for_lcd) == 0)
     {
       if (comp_match_res != NULL)
 	comp_match_res->set_match (symbol_search_name);
@@ -1950,6 +1969,32 @@ test_cp_symbol_name_matches ()
   CHECK_NOT_MATCH_C ("foo::function()", "::function()");
   CHECK_NOT_MATCH_C ("foo::function(int)", "::function()");
   CHECK_NOT_MATCH_C ("foo::function(int)", "::function(int)");
+
+  /* Test ABI tag matching/ignoring.  */
+
+  /* If the symbol name has an ABI tag, but the lookup name doesn't,
+     then the ABI tag in the symbol name is ignored.  */
+  CHECK_MATCH_C ("function[abi:foo]()", "function");
+  CHECK_MATCH_C ("function[abi:foo](int)", "function");
+  CHECK_MATCH_C ("function[abi:foo]()", "function ()");
+  CHECK_NOT_MATCH_C ("function[abi:foo]()", "function (int)");
+
+  CHECK_MATCH_C ("function[abi:foo]()", "function[abi:foo]");
+  CHECK_MATCH_C ("function[abi:foo](int)", "function[abi:foo]");
+  CHECK_MATCH_C ("function[abi:foo]()", "function[abi:foo] ()");
+  CHECK_MATCH_C ("function[abi:foo][abi:bar]()", "function");
+  CHECK_MATCH_C ("function[abi:foo][abi:bar](int)", "function");
+  CHECK_MATCH_C ("function[abi:foo][abi:bar]()", "function[abi:foo]");
+  CHECK_MATCH_C ("function[abi:foo][abi:bar](int)", "function[abi:foo]");
+  CHECK_MATCH_C ("function[abi:foo][abi:bar]()", "function[abi:foo] ()");
+  CHECK_NOT_MATCH_C ("function[abi:foo][abi:bar]()", "function[abi:foo] (int)");
+
+  CHECK_MATCH_C ("function  [abi:foo][abi:bar] ( )", "function [abi:foo]");
+
+  /* If the symbol name does not have an ABI tag, while the lookup
+     name has one, then there's no match.  */
+  CHECK_NOT_MATCH_C ("function()", "function[abi:foo]()");
+  CHECK_NOT_MATCH_C ("function()", "function[abi:foo]");
 }
 
 /* If non-NULL, return STR wrapped in quotes.  Otherwise, return a
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 49c494b..6d23a77 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,5 +1,11 @@
 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.
+
+2017-11-29  Pedro Alves  <palves@redhat.com>
+
 	* gdb.texinfo (Linespec Locations): Document how "function" is
 	interpreted in C++ and Ada.  Document "-qualified".
 	(Explicit Locations): Document how "-function" is interpreted in
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 7a71739..4f55222 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -15128,6 +15128,49 @@ the same notation that is used to declare such symbols in C@t{++}: type
 also use the @value{GDBN} command-line word completion facilities to list the
 available choices, or to finish the type list for you.
 @xref{Completion,, Command Completion}, for details on how to do this.
+
+@item @r{Breakpoints in functions with ABI tags}
+
+The GNU C@t{++} compiler introduced the notion of ABI ``tags'', which
+correspond to changes in the ABI of a type, function, or variable that
+would not otherwise be reflected in a mangled name.  See
+@url{https://developers.redhat.com/blog/2015/02/05/gcc5-and-the-c11-abi/}
+for more detail.
+
+The ABI tags are visible in C@t{++} demangled names.  For example, a
+function that returns a std::string:
+
+@smallexample
+std::string function(int);
+@end smallexample
+
+@noindent
+when compiled for the C++11 ABI is marked with the @code{cxx11} ABI
+tag, and @value{GDBN} displays the symbol like this:
+
+@smallexample
+function[abi:cxx11](int)
+@end smallexample
+
+You can set a breakpoint on such functions simply as if they had no
+tag.  For example:
+
+@smallexample
+(gdb) b function(int)
+Breakpoint 2 at 0x40060d: file main.cc, line 10.
+(gdb) info breakpoints
+Num     Type           Disp Enb Address    What
+1       breakpoint     keep y   0x0040060d in function[abi:cxx11](int)
+                                           at main.cc:10
+@end smallexample
+
+On the rare occasion you need to disambiguate between different ABI
+tags, you can do so by simply including the ABI tag in the function
+name, like:
+
+@smallexample
+(@value{GDBP}) b ambiguous[abi:other_tag](int)
+@end smallexample
 @end table
 
 @node Decimal Floating Point
diff --git a/gdb/language.c b/gdb/language.c
index c05b703..c3872fc 100644
--- a/gdb/language.c
+++ b/gdb/language.c
@@ -707,13 +707,14 @@ default_symbol_name_matcher (const char *symbol_search_name,
 			     completion_match_result *comp_match_res)
 {
   const std::string &name = lookup_name.name ();
-
+  completion_match_for_lcd *match_for_lcd
+    = (comp_match_res != NULL ? &comp_match_res->match_for_lcd : NULL);
   strncmp_iw_mode mode = (lookup_name.completion_mode ()
 			  ? strncmp_iw_mode::NORMAL
 			  : strncmp_iw_mode::MATCH_PARAMS);
 
   if (strncmp_iw_with_mode (symbol_search_name, name.c_str (), name.size (),
-			    mode, language_minimal) == 0)
+			    mode, language_minimal, match_for_lcd) == 0)
     {
       if (comp_match_res != NULL)
 	comp_match_res->set_match (symbol_search_name);
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 909dc32..e9664a0 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -745,6 +745,11 @@ linespec_lexer_lex_string (linespec_parser *parser)
 	      if (PARSER_STREAM (parser)[1] == ':')
 		++(PARSER_STREAM (parser));
 
+	      /* Do not tokenize ABI tags such as "[abi:cxx11]".  */
+	      else if (PARSER_STREAM (parser) - start > 4
+		       && startswith (PARSER_STREAM (parser) - 4, "[abi"))
+		++(PARSER_STREAM (parser));
+
 	      /* Do not tokenify if the input length so far is one
 		 (i.e, a single-letter drive name) and the next character
 		 is a directory separator.  This allows Windows-style
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 690495a..d19eca2 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,11 @@
 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.
+
+2017-11-29  Pedro Alves  <palves@redhat.com>
+
 	* gdb.base/langs.exp: Use -qualified.
 	* gdb.cp/meth-typedefs.exp: Use -qualified, and add tests without
 	it.
diff --git a/gdb/testsuite/gdb.linespec/cpls-abi-tag.cc b/gdb/testsuite/gdb.linespec/cpls-abi-tag.cc
new file mode 100644
index 0000000..3916eda
--- /dev/null
+++ b/gdb/testsuite/gdb.linespec/cpls-abi-tag.cc
@@ -0,0 +1,93 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2017 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#define ABI1 __attribute__ ((abi_tag ("tag1")))
+#define ABI2 __attribute__ ((abi_tag ("tag2")))
+#define ABI3 __attribute__ ((abi_tag ("tag3")))
+
+void ABI1
+test_abi_tag_function (int)
+{
+}
+
+void ABI1
+test_abi_tag_ovld_function ()
+{
+}
+
+void ABI1
+test_abi_tag_ovld_function (int)
+{
+}
+
+/* Code for the overload functions, different ABI tag test.  */
+
+void
+test_abi_tag_ovld2_function ()
+{
+}
+
+void ABI1
+test_abi_tag_ovld2_function (short)
+{
+}
+
+void ABI2
+test_abi_tag_ovld2_function (int)
+{
+}
+
+void ABI2
+test_abi_tag_ovld2_function (long)
+{
+}
+
+struct ABI1 test_abi_tag_struct
+{
+  ABI2 test_abi_tag_struct ();
+  ABI2 ~test_abi_tag_struct ();
+};
+
+test_abi_tag_struct::test_abi_tag_struct ()
+{}
+
+test_abi_tag_struct::~test_abi_tag_struct ()
+{}
+
+ABI3 test_abi_tag_struct s;
+
+/* Code for the abi-tag in parameters test.  */
+
+struct ABI2 abi_tag_param_struct1
+{};
+
+struct ABI2 abi_tag_param_struct2
+{};
+
+void
+test_abi_tag_in_params (abi_tag_param_struct1)
+{}
+
+void
+test_abi_tag_in_params (abi_tag_param_struct1, abi_tag_param_struct2)
+{}
+
+int
+main ()
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.linespec/cpls-abi-tag.exp b/gdb/testsuite/gdb.linespec/cpls-abi-tag.exp
new file mode 100644
index 0000000..9a0dab3
--- /dev/null
+++ b/gdb/testsuite/gdb.linespec/cpls-abi-tag.exp
@@ -0,0 +1,286 @@
+# Copyright 2017 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite.
+
+# Test ABI tag support in linespecs.
+
+load_lib completion-support.exp
+
+standard_testfile cpls-abi-tag.cc
+
+if {[prepare_for_testing "failed to prepare" $testfile \
+	 [list $srcfile] {c++ debug}]} {
+    return -1
+}
+
+gdb_test_no_output "set max-completions unlimited"
+
+# Check that the explicit location completer manages to find the next
+# option name after a -function option, when the -function's argument
+# is a function with an ABI tag.
+
+proc check_explicit_skips_function_argument {function} {
+    test_gdb_complete_unique \
+	"b -function $function -sour" \
+	"b -function $function -source"
+}
+
+# The ABI tag tests.
+
+proc_with_prefix test_abi_tag {} {
+    with_test_prefix "completion" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Complete all prefixes between "_funcio" and the full
+	    # prototype.  The ABI tag is not considered for actual
+	    # completion.
+
+	    with_test_prefix "skip tag" {
+		# set location "test_abi_tag_function\[abi:tag1\](int)"
+		set location "test_abi_tag_function(int)"
+		set line "$cmd_prefix $location"
+		set start [index_after "_functio" $line]
+		test_complete_prefix_range $line $start
+	    }
+
+	    # Now the same, but start completing at the [.  In that case,
+	    # GDB considers the ABI tag as part of actual completion.
+	    with_test_prefix "at tag" {
+		set location "test_abi_tag_function\[abi:tag1\](int)"
+		set line "$cmd_prefix $location"
+		set start [index_after "_function" $line]
+		test_complete_prefix_range $line $start
+	    }
+
+	    # Same, but with extra spaces.  Note that the original spaces in
+	    # the input line are preserved after completion.
+
+	    with_test_prefix "spaces" {
+		test_gdb_complete_unique \
+		    "$cmd_prefix test_abi_tag_function \[abi:tag1\] (" \
+		    "$cmd_prefix test_abi_tag_function \[abi:tag1\] (int)"
+
+		test_gdb_complete_unique \
+		    "$cmd_prefix test_abi_tag_function \[abi:tag1\] ( int " \
+		    "$cmd_prefix test_abi_tag_function \[abi:tag1\] ( int )"
+	    }
+	}
+    }
+
+    with_test_prefix "set breakpoints" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Test setting breakpoints.  If the symbol name has an ABI
+	    # tag, but the input linespec doesn't, then the ABI tag in the
+	    # symbol name is ignored.
+	    set linespec_list {
+		"test_abi_tag_function"
+		"test_abi_tag_function[abi:tag1]"
+		"test_abi_tag_function[abi:tag1](int)"
+		"test_abi_tag_function [abi:tag1]"
+		"test_abi_tag_function [abi:tag1] ( int )"
+		"test_abi_tag_function(int)"
+		"test_abi_tag_function (int)"
+		"test_abi_tag_function ( int )"
+	    }
+	    foreach linespec $linespec_list {
+		check_bp_locations_match_list \
+		    "$cmd_prefix $linespec" [list $location]
+	    }
+	}
+    }
+
+    with_test_prefix "set breakpoints wrong ABI tag" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Test setting breakpoints with the wrong ABI tag.  Should
+	    # fail to create the breakpoints.  Completion should not find
+	    # any match either.
+	    set linespec_list {
+		"test_abi_tag_function[abi:tag2]"
+		"test_abi_tag_function[abi:tag2](int)"
+		"test_abi_tag_function [abi:tag2]"
+		"test_abi_tag_function [abi:tag2] ( int )"
+	    }
+	    foreach linespec $linespec_list {
+		check_setting_bp_fails "$cmd_prefix $linespec"
+		test_gdb_complete_none "$cmd_prefix $linespec"
+	    }
+
+	}
+    }
+
+    # Test completion of overloaded functions with ABI tags.
+    with_test_prefix "completion of overloaded functions" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    set completion_list {
+		"test_abi_tag_ovld_function[abi:tag1]()"
+		"test_abi_tag_ovld_function[abi:tag1](int)"
+	    }
+
+	    # If the input string does not include the ABI tag, then
+	    # actual completion ignores it.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_ovld_f" "unction(" \
+		$completion_list
+
+	    # Otherwise, it's considered.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_ovld_function\[" "abi:tag1\](" \
+		$completion_list
+
+	}
+    }
+
+    # Test setting breakpoints on overloaded functions with ABI tags.
+    with_test_prefix "breakpoints on overloaded functions" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    set completion_list {
+		"test_abi_tag_ovld_function[abi:tag1]()"
+		"test_abi_tag_ovld_function[abi:tag1](int)"
+	    }
+	    set location_list {
+		"test_abi_tag_ovld_function"
+		"test_abi_tag_ovld_function[abi:tag1]"
+	    }
+	    foreach linespec $location_list {
+		check_bp_locations_match_list \
+		    "$cmd_prefix $linespec" $completion_list
+	    }
+
+	}
+    }
+
+    with_test_prefix "completion of overloaded functions different abi" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Test completion of overloaded functions with ABI tags.
+	    set completion_list {
+		"test_abi_tag_ovld2_function()"
+		"test_abi_tag_ovld2_function[abi:tag1](short)"
+		"test_abi_tag_ovld2_function[abi:tag2](int)"
+		"test_abi_tag_ovld2_function[abi:tag2](long)"
+	    }
+
+	    # If the input string does not include the ABI tag, then
+	    # actual completion ignores it.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_ovld2_f" "unction(" \
+		$completion_list
+
+	    # Otherwise, it's considered.  Match stops at the part of
+	    # the tag that diverges, and the completion list only
+	    # shows matches with ABI tags.
+	    set completion_list {
+		"test_abi_tag_ovld2_function[abi:tag1](short)"
+		"test_abi_tag_ovld2_function[abi:tag2](int)"
+		"test_abi_tag_ovld2_function[abi:tag2](long)"
+	    }
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_ovld2_function\[" "abi:tag" \
+		$completion_list
+
+	    # If you disambiguate, matches include only locations for
+	    # the specified tag.
+	    set completion_list {
+		"test_abi_tag_ovld2_function[abi:tag2](int)"
+		"test_abi_tag_ovld2_function[abi:tag2](long)"
+	    }
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_ovld2_function\[abi:tag2" "\](" \
+		$completion_list
+
+	    test_gdb_complete_unique \
+		"$cmd_prefix test_abi_tag_ovld2_function\[abi:tag1" \
+		"$cmd_prefix test_abi_tag_ovld2_function\[abi:tag1\](short)"
+	}
+    }
+
+    with_test_prefix "completion of struct prefixes with tags" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Test completion of methods of structs with ABI tags.
+	    set completion_list {
+		"test_abi_tag_struct[abi:tag1]::test_abi_tag_struct[abi:tag2]()"
+		"test_abi_tag_struct[abi:tag1]::~test_abi_tag_struct[abi:tag2]()"
+	    }
+
+	    # If the input string does not include the ABI tag, then
+	    # actual completion ignores it.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_struc" "t::" \
+		$completion_list
+
+	    # Otherwise, it's considered.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_struct\[" "abi:tag1\]::" \
+		$completion_list
+
+	    # Mix and match different abi tag positions.
+	    test_gdb_complete_unique \
+		"$cmd_prefix test_abi_tag_struct::t" \
+		"$cmd_prefix test_abi_tag_struct::test_abi_tag_struct()"
+
+	    test_gdb_complete_unique \
+		"$cmd_prefix test_abi_tag_struct\[abi:tag1\]::t" \
+		"$cmd_prefix test_abi_tag_struct\[abi:tag1\]::test_abi_tag_struct()"
+
+	    test_gdb_complete_unique \
+		"$cmd_prefix test_abi_tag_struct\[abi:tag1\]::test_abi_tag_struct\[" \
+		"$cmd_prefix test_abi_tag_struct\[abi:tag1\]::test_abi_tag_struct\[abi:tag2\]()"
+	}
+    }
+
+    with_test_prefix "abi tag in parameters" {
+	foreach cmd_prefix {"b" "b -function"} {
+	    # Complete all prefixes between "_funcio" and the full
+	    # prototype.  The ABI tag is not considered for actual
+	    # completion.
+
+	    set completion_list {
+		"test_abi_tag_in_params(abi_tag_param_struct1[abi:tag2])"
+		"test_abi_tag_in_params(abi_tag_param_struct1[abi:tag2], abi_tag_param_struct2[abi:tag2])"
+	    }
+	    # If the input string does not include the ABI tag, then
+	    # actual completion ignores it.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_in_para" "ms(abi_tag_param_struct1" \
+		$completion_list
+
+	    # If OTOH the input string includes the ABI tag, then it
+	    # is considered.
+	    test_gdb_complete_multiple \
+		"$cmd_prefix " "test_abi_tag_in_params(abi_tag_param_struct1\[ab" "i:tag2\]"\
+		$completion_list
+
+	    set location_list {
+		"test_abi_tag_in_params(abi_tag_param_struct1[abi:tag2], abi_tag_param_struct2[abi:tag2])"
+	    }
+
+	    set tags {"" "\[abi:tag2\]"}
+	    foreach tag1 $tags {
+		foreach tag2 $tags {
+		    set linespec "test_abi_tag_in_params(abi_tag_param_struct1${tag1}, abi_tag_param_struct2${tag2})"
+		    check_bp_locations_match_list \
+			"$cmd_prefix $linespec" $location_list
+		}
+	    }
+	}
+    }
+
+    # Check that the explicit location completer manages to find the
+    # option name after -function, when the -function's argument is a
+    # function with an ABI tag.
+    check_explicit_skips_function_argument \
+	"test_abi_tag_function\[abi:unknown\](int)"
+}
+
+test_abi_tag
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 != '(');
     }
diff --git a/gdb/utils.h b/gdb/utils.h
index dff4b17..349ab93 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -49,15 +49,19 @@ enum class strncmp_iw_mode
 /* Helper for strcmp_iw and strncmp_iw.  Exported so that languages
    can implement both NORMAL and MATCH_PARAMS variants in a single
    function and defer part of the work to strncmp_iw_with_mode.
+
    LANGUAGE is used to implement some context-sensitive
    language-specific comparisons.  For example, for C++,
    "string1=operator()" should not match "string2=operator" even in
-   MATCH_PARAMS mode.  */
-extern int strncmp_iw_with_mode (const char *string1,
-				 const char *string2,
-				 size_t string2_len,
-				 strncmp_iw_mode mode,
-				 enum language language);
+   MATCH_PARAMS mode.
+
+   MATCH_FOR_LCD is passed down so that the function can mark parts of
+   the symbol name as ignored for completion matching purposes (e.g.,
+   to handle abi tags).  */
+extern int strncmp_iw_with_mode
+  (const char *string1, const char *string2, size_t string2_len,
+   strncmp_iw_mode mode, enum language language,
+   completion_match_for_lcd *match_for_lcd = NULL);
 
 /* Do a strncmp() type operation on STRING1 and STRING2, ignoring any
    differences in whitespace.  STRING2_LEN is STRING2's length.