[gdb/symtab] Fix missing breakpoint location for inlined function

Consider the test-case contained in this patch.

With -readnow, we have two breakpoint locations:
...
$ gdb -readnow -batch breakpoint-locs -ex "b N1::C1::baz" -ex "info break"
Breakpoint 1 at 0x4004cb: N1::C1::baz. (2 locations)
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   <MULTIPLE>
1.1                         y   0x00000000004004cb in N1::C1::baz() \
                                                     at breakpoint-locs.h:6
1.2                         y   0x00000000004004f0 in N1::C1::baz() \
                                                     at breakpoint-locs.h:6
...

But without -readnow, we have instead only one breakpoint location:
...
$ gdb -batch breakpoint-locs -ex "b N1::C1::baz" -ex "info break"
Breakpoint 1 at 0x4004f0: file breakpoint-locs.h, line 6.
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x00000000004004f0 in N1::C1::baz() \
                                                     at breakpoint-locs.h:6
...

The relevant dwarf is this bit:
...
 <0><d2>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <d8>   DW_AT_name        : breakpoint-locs.cc
 <1><f4>: Abbrev Number: 2 (DW_TAG_namespace)
    <f5>   DW_AT_name        : N1
 <2><fe>: Abbrev Number: 3 (DW_TAG_class_type)
    <ff>   DW_AT_name        : C1
 <3><109>: Abbrev Number: 4 (DW_TAG_subprogram)
    <10a>   DW_AT_name        : baz
    <110>   DW_AT_linkage_name: _ZN2N12C13bazEv
 <2><116>: Abbrev Number: 5 (DW_TAG_subprogram)
    <117>   DW_AT_name        : foo
    <11d>   DW_AT_linkage_name: _ZN2N13fooEv
 <1><146>: Abbrev Number: 8 (DW_TAG_subprogram)
    <147>   DW_AT_specification: <0x116>
    <14b>   DW_AT_low_pc      : 0x4004c7
    <153>   DW_AT_high_pc     : 0x10
 <2><161>: Abbrev Number: 9 (DW_TAG_inlined_subroutine)
    <162>   DW_AT_abstract_origin: <0x194>
    <166>   DW_AT_low_pc      : 0x4004cb
    <16e>   DW_AT_high_pc     : 0x9
 <1><194>: Abbrev Number: 12 (DW_TAG_subprogram)
    <195>   DW_AT_specification: <0x109>
    <199>   DW_AT_inline      : 3       (declared as inline and inlined)
...

The missing breakpoint location is specified by DIE 0x161, which is ignored by
the partial DIE reader because it's a child of a DW_TAG_subprogram DIE (at
0x146, for foo).

Fix this by not ignoring the DIE during partial DIE reading.

Tested on x86_64-linux.

gdb/ChangeLog:

2020-06-03  Tom de Vries  <tdevries@suse.de>

	PR symtab/26046
	* dwarf2/read.c (scan_partial_symbols): Recurse into DW_TAG_subprogram
	children for C++.
	(load_partial_dies): Don't skip DW_TAG_inlined_subroutine child of
	DW_TAG_subprogram.

gdb/testsuite/ChangeLog:

2020-06-03  Tom de Vries  <tdevries@suse.de>

	PR symtab/26046
	* gdb.cp/breakpoint-locs-2.cc: New test.
	* gdb.cp/breakpoint-locs.cc: New test.
	* gdb.cp/breakpoint-locs.exp: New file.
	* gdb.cp/breakpoint-locs.h: New test.

7 files changed, 135 insertions, 1 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 3936517..98f4d17 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2020-06-03  Tom de Vries  <tdevries@suse.de>
+
+	PR symtab/26046
+	* dwarf2/read.c (scan_partial_symbols): Recurse into DW_TAG_subprogram
+	children for C++.
+	(load_partial_dies): Don't skip DW_TAG_inlined_subroutine child of
+	DW_TAG_subprogram.
+
 2020-06-02  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* ada-lang.c (ada_language_data): Delete skip_trampoline
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index e6566f9..ac6c15e 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -8146,6 +8146,9 @@ scan_partial_symbols (struct partial_die_info *first_die, CORE_ADDR *lowpc,
 	    case DW_TAG_subprogram:
 	    case DW_TAG_inlined_subroutine:
 	      add_partial_subprogram (pdi, lowpc, highpc, set_addrmap, cu);
+	      if (cu->language == language_cplus)
+		scan_partial_symbols (pdi->die_child, lowpc, highpc,
+				      set_addrmap, cu);
 	      break;
 	    case DW_TAG_constant:
 	    case DW_TAG_variable:
@@ -18246,7 +18249,8 @@ load_partial_dies (const struct die_reader_specs *reader,
       if (!load_all
 	  && cu->language == language_cplus
 	  && parent_die != NULL
-	  && parent_die->tag == DW_TAG_subprogram)
+	  && parent_die->tag == DW_TAG_subprogram
+	  && abbrev->tag != DW_TAG_inlined_subroutine)
 	{
 	  info_ptr = skip_one_die (reader, info_ptr + bytes_read, abbrev);
 	  continue;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 21839c7..21cfc17 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,13 @@
 2020-06-03  Tom de Vries  <tdevries@suse.de>
 
+	PR symtab/26046
+	* gdb.cp/breakpoint-locs-2.cc: New test.
+	* gdb.cp/breakpoint-locs.cc: New test.
+	* gdb.cp/breakpoint-locs.exp: New file.
+	* gdb.cp/breakpoint-locs.h: New test.
+
+2020-06-03  Tom de Vries  <tdevries@suse.de>
+
 	PR testsuite/25609
 	* gdb.base/jit-elf-so.exp: Don't modify testing behaviour based on
 	value of global verbose.
diff --git a/gdb/testsuite/gdb.cp/breakpoint-locs-2.cc b/gdb/testsuite/gdb.cp/breakpoint-locs-2.cc
new file mode 100644
index 0000000..8e0cce8
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/breakpoint-locs-2.cc
@@ -0,0 +1,29 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2020 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/>.  */
+
+#include "breakpoint-locs.h"
+
+namespace N1
+{
+  void bar () { C1::baz (); }
+}
+
+void
+N1_bar (void)
+{
+  N1::bar ();
+}
diff --git a/gdb/testsuite/gdb.cp/breakpoint-locs.cc b/gdb/testsuite/gdb.cp/breakpoint-locs.cc
new file mode 100644
index 0000000..d52a3f4
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/breakpoint-locs.cc
@@ -0,0 +1,33 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2020 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/>.  */
+
+#include "breakpoint-locs.h"
+
+namespace N1
+{
+  void foo () { C1::baz (); }
+}
+
+extern void N1_bar (void);
+
+int
+main ()
+{
+  N1::foo ();
+  N1_bar ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.cp/breakpoint-locs.exp b/gdb/testsuite/gdb.cp/breakpoint-locs.exp
new file mode 100644
index 0000000..46b64e9
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/breakpoint-locs.exp
@@ -0,0 +1,27 @@
+# Copyright 2020 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
+
+if {[skip_cplus_tests]} { continue }
+
+standard_testfile .cc breakpoint-locs-2.cc
+
+if { [prepare_for_testing "failed to prepare" $testfile "$srcfile $srcfile2"\
+	  {debug c++}] } {
+    return -1
+}
+
+gdb_test "break N1::C1::baz" "\\(2 locations\\)"
diff --git a/gdb/testsuite/gdb.cp/breakpoint-locs.h b/gdb/testsuite/gdb.cp/breakpoint-locs.h
new file mode 100644
index 0000000..61af594
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/breakpoint-locs.h
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2020 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/>.  */
+
+namespace N1
+{
+  class C1
+  {
+   public:
+    static void __attribute__((always_inline)) baz () { volatile unsigned i; i++; }
+  };
+}