[binutils-gdb] Improve GDB's baseclass detection with typedefs

[binutils-gdb] Improve GDB's baseclass detection with typedefs

[Bruno Larsen]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2820f08f2331820808ac2f54d8e3619f36ea258b

commit 2820f08f2331820808ac2f54d8e3619f36ea258b
Author: Bruno Larsen <blarsen@redhat.com>
Date:   Fri Sep 23 11:36:02 2022 +0200

    Improve GDB's baseclass detection with typedefs
    
    When a class inherits from a typedef'd baseclass, GDB may be unable to
    find the baseclass if the user is not using the typedef'd name, as is
    tested on gdb.cp/virtbase2.exp; the reason that test case is working
    under gcc is that the dwarf generated by gcc links the class to the
    original definition of the baseclass, not to the typedef.  If the
    inheritance is linked to the typedef, such as how clang does it,
    gdb.cp/virtbase2.exp starts failing.
    
    This can also be seen in gdb.cp/impl-this.exp, when attempting to print
    D::Bint::i, and GDB not being able to find the baseclass Bint.
    
    This happens because searching for baseclasses only uses the macro
    TYPE_BASECLASS_NAME, which returns the typedef'd name. However, we can't
    switch that macro to checking for typedefs, otherwise we wouldn't be
    able to find the typedef'd name anymore. This is fixed by searching for
    members or baseclasses by name, we check both the saved name and the
    name after checking for typedefs.
    
    This also fixes said long-standing bug in gdb.cp/impl-this.exp when the
    compiler adds information about typedefs in the debuginfo.

Diff:
---
 gdb/cp-namespace.c                 |  5 +++--
 gdb/testsuite/gdb.cp/impl-this.exp | 45 ++++++++++++++++++++++++++++----------
 gdb/valops.c                       |  4 +---
 3 files changed, 37 insertions(+), 17 deletions(-)

diff --git a/gdb/cp-namespace.c b/gdb/cp-namespace.c
index 837eafc52f1..1d7759a7669 100644
--- a/gdb/cp-namespace.c
+++ b/gdb/cp-namespace.c
@@ -780,12 +780,13 @@ cp_find_type_baseclass_by_name (struct type *parent_type, const char *name)
   for (i = 0; i < TYPE_N_BASECLASSES (parent_type); ++i)
     {
       struct type *type = check_typedef (TYPE_BASECLASS (parent_type, i));
-      const char *base_name = TYPE_BASECLASS_NAME (parent_type, i);
+      const char *tdef_name = TYPE_BASECLASS_NAME (parent_type, i);
+      const char *base_name = type->name ();
 
       if (base_name == NULL)
 	continue;
 
-      if (streq (base_name, name))
+      if (streq (tdef_name, name) || streq (base_name, name))
 	return type;
 
       type = cp_find_type_baseclass_by_name (type, name);
diff --git a/gdb/testsuite/gdb.cp/impl-this.exp b/gdb/testsuite/gdb.cp/impl-this.exp
index 2910bf7d79d..4a11fb21823 100644
--- a/gdb/testsuite/gdb.cp/impl-this.exp
+++ b/gdb/testsuite/gdb.cp/impl-this.exp
@@ -26,6 +26,8 @@ if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
     return -1
 }
 
+set gcc_used [test_compiler_info gcc-*-*]
+
 # First test expressions when there is no context.
 with_test_prefix "before run" {
     gdb_test "print i" "No symbol \"i\" in current context."
@@ -63,15 +65,23 @@ with_test_prefix "at D::f (valid expressions)" {
     gdb_test "print D::i" "= 4"
     gdb_test "print D::B<int>::i" "= 2"
     gdb_test "print B<int>::i" "= 2"
-    gdb_test "print D::Bint::i" \
-	"No type \"Bint\" within class or namespace \"D\"."
+
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::i" "= 2"
+
     gdb_test "print Bint::i" "= 2"
     gdb_test "print D::C::i" "= 3"
     gdb_test "print C::i" "= 3"
     gdb_test "print D::B<int>::A<int>::i" "= 1"
     gdb_test "print B<int>::A<int>::i" "= 1"
-    gdb_test "print D::Bint::A<int>::i" \
-	"No type \"Bint\" within class or namespace \"D\"."
+
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::A<int>::i" "= 1"
+
     gdb_test "print Bint::A<int>::i" "= 1"
     gdb_test "print A<int>::i" "= 1"
     gdb_test "print D::C::A<int>::i" "= 1"
@@ -88,11 +98,16 @@ with_test_prefix "at D::f (valid expressions)" {
 with_test_prefix "at D::f (invalid expressions)" {
     gdb_test "print D::B<int>::c" "There is no field named c"
     gdb_test "print D::B<int>::A<int>::c" "There is no field named c"
-    gdb_test "print D::Bint::c" \
-	"No type \"Bint\" within class or namespace \"D\"."
 
-    gdb_test "print D::Bint::A<int>::c" \
-	"No type \"Bint\" within class or namespace \"D\"."
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::c" "There is no field named c"
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::A<int>::c" "There is no field named c"
+
     gdb_test "print D::C::A<int>::c" "There is no field named c"
     gdb_test "print B<int>::c" "There is no field named c"
     gdb_test "print B<int>::A<int>::c" "There is no field named c"
@@ -101,10 +116,16 @@ with_test_prefix "at D::f (invalid expressions)" {
     gdb_test "print C::A<int>::c" "There is no field named c"
     gdb_test "print D::B<int>::x" "There is no field named x"
     gdb_test "print D::B<int>::A<int>::x" "There is no field named x"
-    gdb_test "print D::Bint::x" \
-	"No type \"Bint\" within class or namespace \"D\"."
-    gdb_test "print D::Bint::A<int>::x" \
-	"No type \"Bint\" within class or namespace \"D\"."
+
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::x" "There is no field named x"
+    if {$gcc_used} {
+	setup_xfail *-*-* gcc/60833
+    }
+    gdb_test "print D::Bint::A<int>::x" "There is no field named x"
+
     gdb_test "print B<int>::x" "There is no field named x"
     gdb_test "print B<int>::A<int>::x" "There is no field named x"
     gdb_test "print Bint::x" "There is no field named x"
diff --git a/gdb/valops.c b/gdb/valops.c
index 0a215d699a1..de8a68888e4 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -2066,9 +2066,7 @@ struct_field_searcher::search (struct value *arg1, LONGEST offset,
 	 name is not yet filled in.  */
       int found_baseclass = (m_looking_for_baseclass
 			     && TYPE_BASECLASS_NAME (type, i) != NULL
-			     && (strcmp_iw (m_name,
-					    TYPE_BASECLASS_NAME (type,
-								 i)) == 0));
+			     && (strcmp_iw (m_name, basetype->name ()) == 0));
       LONGEST boffset = value_embedded_offset (arg1) + offset;
 
       if (BASETYPE_VIA_VIRTUAL (type, i))