[RFA] Fix namespace aliases (c++/7539, c++/10541)

[Keith Seitz <keiths at redhat dot com>]

Hi,

This is an attempt to fix namespace alias bugs reported in c++/7539 and 
c++/10541.

There are several problems here. First, previous versions of gcc did not 
output the proper debuginfo. As a result, I've resorted to using the 
DWARF assembler for testing. Basically any gcc > 4.2.4 should work, 
though. [I know that's ancient, but ...]

The next problem was getting all the aliases recorded into the symbol 
table. I've made some changes to dwarf2read.c to do this.

With this change, the expression parser pretty much works as-is. The 
remaining problem is the linespec parser.

That was resolved by modifying cp_canonical_string_no_typedefs to do 
namespace alias substitutions. [I really think I should have named this 
cp_canonicalize_string_for_lookup or something similar.]

With this find_linespec_symbols can then properly look for an actual 
symbol that is in the symbol table.

Tested, regression-free, with x86_64 native and native-gdbserver.

Keith

ChangeLog
2013-07-26  Keith Seitz  <keiths@redhat.com>

	PR c++/7539
	PR c++/10541
	* cp-support.c (insepct_type): Add support for substituting
	namespace aliases, too.
	* dwarf2read.c (scan_partial_symbols): Add a partial symbol
	for DW_TAG_imported_declaration.
	(add_partial_symbol): Likewise.
	(process_die): Handle namespace aliases.
	(die_needs_namespace): Add DW_TAG_imported_declaration.
	(load_partial_dies): Load DW_TAG_imported_declaration, too.
	(new_symbol_full): Handle DW_TAG_imported_declaration.

testsuite/ChangeLog
2013-07-26  Keith Seitz  <keiths@redhat.com>

	PR c++/7935
	PR c++/10541
	* gdb.cp/nsalias.exp: New file.
	* gdb.cp/nsalias.cc: New file.
	* gdb.cp/nsrecurs.exp: Remove kfails. Conditionally run
	tests only on known, working compiler versions.

diff --git a/gdb/cp-support.c b/gdb/cp-support.c
index 3c1442d..623c0da 100644
--- a/gdb/cp-support.c
+++ b/gdb/cp-support.c
@@ -200,8 +200,9 @@ inspect_type (struct demangle_parse_info *info,
 	  return 0;
 	}
 
-      /* If the type is a typedef, replace it.  */
-      if (TYPE_CODE (otype) == TYPE_CODE_TYPEDEF)
+      /* If the type is a typedef or namespace alias, replace it.  */
+      if (TYPE_CODE (otype) == TYPE_CODE_TYPEDEF
+	  || TYPE_CODE (otype) == TYPE_CODE_NAMESPACE)
 	{
 	  long len;
 	  int is_anon;
@@ -212,6 +213,13 @@ inspect_type (struct demangle_parse_info *info,
 	  /* Get the real type of the typedef.  */
 	  type = check_typedef (otype);
 
+	  /* If the symbol is a namespace and its name is no different
+	     than the name we looked up, this symbol is not a namespace
+	     alias and does not need to be substituted.  */
+	  if (TYPE_CODE (otype) == TYPE_CODE_NAMESPACE
+	      && strcmp (TYPE_NAME (type), name) == 0)
+	    return 0;
+
 	  is_anon = (TYPE_TAG_NAME (type) == NULL
 		     && (TYPE_CODE (type) == TYPE_CODE_ENUM
 			 || TYPE_CODE (type) == TYPE_CODE_STRUCT
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 04993c2..cd74abf 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -6244,6 +6244,9 @@ scan_partial_symbols (struct partial_die_info *first_die, CORE_ADDR *lowpc,
 			       cu->per_cu->imported_symtabs, per_cu);
 	      }
 	      break;
+	    case DW_TAG_imported_declaration:
+	      add_partial_symbol (pdi, cu);
+	      break;
 	    default:
 	      break;
 	    }
@@ -6515,6 +6518,7 @@ add_partial_symbol (struct partial_die_info *pdi, struct dwarf2_cu *cu)
 			   &objfile->static_psymbols,
 			   0, (CORE_ADDR) 0, cu->language, objfile);
       break;
+    case DW_TAG_imported_declaration:
     case DW_TAG_namespace:
       add_psymbol_to_list (actual_name, strlen (actual_name),
 			   built_actual_name != NULL,
@@ -7732,6 +7736,32 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
       read_module (die, cu);
       break;
     case DW_TAG_imported_declaration:
+      {
+	struct attribute *attr;
+
+	attr = dwarf2_attr (die, DW_AT_import, cu);
+	if (attr != NULL)
+	  {
+	    /* If the die does not have a name, this is not a namespace
+	       alias.  */
+	    attr = dwarf2_attr (die, DW_AT_name, cu);
+	    if (attr != NULL)
+	      {
+		struct type *type;
+		sect_offset offset = dwarf2_get_ref_die_offset (attr);
+
+		type = get_die_type_at_offset (offset, cu->per_cu);
+		if (type != NULL && TYPE_CODE (type) == TYPE_CODE_NAMESPACE)
+		  {
+		    /* This declaration is a global namespace alias.  Add
+		       a symbol for it whose type is the aliased namespace.  */
+		    new_symbol (die, type, cu);
+		    break;
+		  }
+	      }
+	  }
+      }
+      /* The declaration is not a global namespace alias: fall through.  */
     case DW_TAG_imported_module:
       cu->processing_has_namespace_info = 1;
       if (die->child != NULL && (die->tag == DW_TAG_imported_declaration
@@ -7774,6 +7804,7 @@ die_needs_namespace (struct die_info *die, struct dwarf2_cu *cu)
     case DW_TAG_enumerator:
     case DW_TAG_subprogram:
     case DW_TAG_member:
+    case DW_TAG_imported_declaration:
       return 1;
 
     case DW_TAG_variable:
@@ -14013,7 +14044,8 @@ load_partial_dies (const struct die_reader_specs *reader,
 	  && abbrev->tag != DW_TAG_namespace
 	  && abbrev->tag != DW_TAG_module
 	  && abbrev->tag != DW_TAG_member
-	  && abbrev->tag != DW_TAG_imported_unit)
+	  && abbrev->tag != DW_TAG_imported_unit
+	  && abbrev->tag != DW_TAG_imported_declaration)
 	{
 	  /* Otherwise we skip to the next sibling, if any.  */
 	  info_ptr = skip_one_die (reader, info_ptr + bytes_read, abbrev);
@@ -16731,6 +16763,7 @@ new_symbol_full (struct die_info *die, struct type *type, struct dwarf2_cu *cu,
 			   ? &global_symbols : cu->list_in_scope);
 	  }
 	  break;
+	case DW_TAG_imported_declaration:
 	case DW_TAG_namespace:
 	  SYMBOL_ACLASS_INDEX (sym) = LOC_TYPEDEF;
 	  list_to_add = &global_symbols;
diff --git a/gdb/testsuite/gdb.cp/nsalias.cc b/gdb/testsuite/gdb.cp/nsalias.cc
new file mode 100644
index 0000000..be2dfbe
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/nsalias.cc
@@ -0,0 +1,23 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2013 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/>.  */
+
+int
+main ()
+{
+  return 0;
+}
+
diff --git a/gdb/testsuite/gdb.cp/nsalias.exp b/gdb/testsuite/gdb.cp/nsalias.exp
new file mode 100644
index 0000000..a23f293
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/nsalias.exp
@@ -0,0 +1,226 @@
+# Copyright 2013 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/>.
+
+# Test namespace aliases.
+# PRs c++/7935, c++/10541
+
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    return 0
+}
+
+if {[skip_cplus_tests]} {
+    continue
+}
+
+standard_testfile .cc nsalias-dw.S
+
+# Make the DWARF used for the test.  This is necessary to work
+# around compiler issues.  Not all versions of gcc output the
+# correct debuginfo we need.
+#
+# This should create the equivalent DWARF to:
+#
+# namespace outer
+# {
+#   namespace inner
+#   {
+#     namespace innermost
+#     {
+#       const int x = 2;
+#       int foo (void) { return x; }
+#     }
+#
+#     namespace Innermost = innermost;
+#
+#     const int x = 1;
+#     int foo (void) { return x + Innermost::foo (); }
+#   }
+#
+#   namespace Inner = inner;
+#
+#   const int x = 0;
+#   int foo (void) { return x + Inner::foo (); }
+# }
+#
+# namespace Outer = outer;
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    cu {} {
+	compile_unit {{language @DW_LANG_C_plus_plus}} {
+	    declare_labels int_label outer_label inner_label innermost_label
+	    declare_labels im_foo_label i_foo_label o_foo_label
+
+	    int_label: base_type {
+		{name int}
+		{encoding @DW_ATE_signed}
+		{byte_size 4 DW_FORM_sdata}
+	    }
+
+	    outer_label: DW_TAG_namespace {
+		{name outer}
+	    } {
+		inner_label: DW_TAG_namespace {
+		    {name inner}
+		} {
+		    innermost_label: DW_TAG_namespace {
+			{name innermost}
+		    } {
+			DW_TAG_variable {
+			    {name x}
+			    {type :$int_label}
+			    {const_value 2 DW_FORM_data1}
+			}
+
+			im_foo_label: DW_TAG_subprogram {
+			    {name foo}
+			    {external 1}
+			    {declaration 1}
+			}
+		    }
+
+		    imported_declaration {
+			{name Innermost}
+			{import :$innermost_label}
+		    }
+
+		    DW_TAG_variable {
+			{name x}
+			{type :$int_label}
+			{const_value 1 DW_FORM_data1}
+		    }
+
+		    i_foo_label: subprogram {
+			{name foo}
+			{external 1}
+			{declaration 1}
+		    }
+		}
+
+		imported_declaration {
+		    {name Inner}
+		    {import :$inner_label}
+		}
+
+		DW_TAG_variable {
+		    {name x}
+		    {type :$int_label}
+		    {const_value 0 DW_FORM_data1}
+		}
+
+		o_foo_label: subprogram {
+		    {name foo}
+		    {external 1}
+		    {declaration 1}
+		}
+	    }
+
+	    imported_declaration {
+		{name Outer}
+		{import :$outer_label}
+	    }
+
+	    subprogram {
+		{specification :$im_foo_label}
+		{low_pc 0x0}
+		{high_pc 0x1}
+	    }
+
+	    subprogram {
+		{specification :$i_foo_label}
+		{low_pc 0x2}
+		{high_pc 0x3}
+	    }
+
+	    subprogram {
+		{specification :$o_foo_label}
+		{low_pc 0x4}
+		{high_pc 0x5}
+	    }
+	}
+    }
+}
+
+if {[gdb_compile $srcdir/$subdir/$srcfile ${binfile}1.o \
+	 object {c++ debug}] != ""} {
+    return -1
+}
+
+if {[gdb_compile $asm_file ${binfile}2.o object {nodebug}] != ""} {
+    return -1
+}
+
+if {[gdb_compile [list ${binfile}1.o ${binfile}2.o] \
+	 $binfile executable {c++}] != ""} {
+    return -1
+}
+
+clean_restart $testfile
+
+# A procedure to run various tests on aliased namespaces.
+proc do_alias_tests {ns} {
+
+    # The "real" namespace is simply NS in all lowercase.
+    set real [string tolower $ns]
+
+    # The value of `x' is the number of '::' in NS.
+    set x [expr {[llength [split $ns ":"]] / 2}]
+
+    # Test "whatis"
+    gdb_test "whatis $ns" "type = $real"
+
+    # Test "ptype"
+    gdb_test "ptype $ns" "type = namespace $real"
+
+    # Print 'x'
+    send_log "expecting x = $x\n"
+    gdb_test "print ${ns}::x" " = $x"
+
+    # Attempt to list the function.
+    gdb_test_no_output "list ${ns}::foo"
+
+    # Attempt to break on the start of the function.
+    gdb_breakpoint "*${ns}::foo"
+
+    # And then erase it
+    with_test_prefix "($ns)" {
+	gdb_test_no_output "delete \$bpnum"
+    }
+}
+
+# This is a list of all the permutations to be tested.  For troubleshooting
+# purposes, this list is explicitly enumerated.
+
+set permutations {}
+lappend permutations "outer"
+lappend permutations "Outer"
+lappend permutations "outer::inner"
+lappend permutations "Outer::inner"
+lappend permutations "outer::Inner"
+lappend permutations "Outer::Inner"
+lappend permutations "outer::inner::innermost"
+lappend permutations "outer::inner::Innermost"
+lappend permutations "outer::Inner::innermost"
+lappend permutations "outer::Inner::Innermost"
+lappend permutations "Outer::inner::innermost"
+lappend permutations "Outer::inner::Innermost"
+lappend permutations "Outer::Inner::innermost"
+lappend permutations "Outer::Inner::Innermost"
+
+foreach p $permutations {
+    do_alias_tests $p
+}
diff --git a/gdb/testsuite/gdb.cp/nsrecurs.exp b/gdb/testsuite/gdb.cp/nsrecurs.exp
index 0537e89..9cf4331 100644
--- a/gdb/testsuite/gdb.cp/nsrecurs.exp
+++ b/gdb/testsuite/gdb.cp/nsrecurs.exp
@@ -52,8 +52,10 @@ gdb_test "print xx" "= 999"
 # Test printing using recursive namespace
 # aliases.
 
-setup_kfail "gdb/10541" "*-*-*"
-gdb_test "ptype G::GF" "= namespace F"
+if {![test_compiler_info {gcc-[0-3]-*}]} {
+    gdb_test "ptype G::GF" "= namespace F"
 
-setup_kfail "gdb/10541" "*-*-*"
-gdb_test "print G::GF::FE::ex" "= 9999"
+    if {![test_compiler_info {gcc-4-[0-3]-*}]} {
+	gdb_test "print G::GF::FE::ex" "= 9999"
+    }
+}