PR c++/14819: Explicit class:: inside class scope does not work

https://sourceware.org/ml/gdb-patches/2013-11/msg00102.html

gdb/ChangeLog

@@ -1,3 +1,15 @@
+2013-11-25  Keith Seitz  <keiths@redhat.com>
+
+	PR c++/14819
+	* c-exp.y (classify_inner_name): If no matching symbol was
+	found, try looking up the token as a base class.
+	Likewise if a constructor was found.
+	* cp-namespace.c (find_type_baseclass_by_name): New function.
+	* cp-support.h (find_type_baseclass_by_name): Declare.
+	* valops.c (value_struct_elt_for_reference): If we get
+	a non-static field, try to get a value based on the
+	current instance, if any.
+
 2013-11-24  Yao Qi  <yao@codesourcery.com>
 
 	* disasm.c (dis_asm_read_memory): Call target_read_code

gdb/c-exp.y

@@ -2960,13 +2960,39 @@ classify_inner_name (const struct block *block, struct type *context)
 
   copy = copy_name (yylval.ssym.stoken);
   yylval.ssym.sym = cp_lookup_nested_symbol (type, copy, block);
+
+  /* If no symbol was found, search for a matching base class named
+     COPY.  This will allow users to enter qualified names of class members
+     relative to the `this' pointer.  */
   if (yylval.ssym.sym == NULL)
-    return ERROR;
+    {
+      struct type *base_type = find_type_baseclass_by_name (type, copy);
+
+      if (base_type != NULL)
+	{
+	  yylval.tsym.type = base_type;
+	  return TYPENAME;
+	}
+
+      return ERROR;
+    }
 
   switch (SYMBOL_CLASS (yylval.ssym.sym))
     {
     case LOC_BLOCK:
     case LOC_LABEL:
+      /* cp_lookup_nested_symbol might have accidentally found a constructor
+	 named COPY when we really wanted a base class of the same name.
+	 Double-check this case by looking for a base class.  */
+      {
+	struct type *base_type = find_type_baseclass_by_name (type, copy);
+
+	if (base_type != NULL)
+	  {
+	    yylval.tsym.type = base_type;
+	    return TYPENAME;
+	  }
+      }
       return ERROR;
 
     case LOC_TYPEDEF:

gdb/cp-namespace.c

@@ -703,6 +703,34 @@ lookup_symbol_file (const char *name,
   return sym;
 }
 
+/* Search through the base classes of PARENT_TYPE for a base class
+   named NAME and return its type.  If not found, return NULL.  */
+
+struct type *
+find_type_baseclass_by_name (struct type *parent_type, const char *name)
+{
+  int i;
+
+  CHECK_TYPEDEF (parent_type);
+  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);
+
+      if (base_name == NULL)
+	continue;
+
+      if (streq (base_name, name))
+	return type;
+
+      type = find_type_baseclass_by_name (type, name);
+      if (type != NULL)
+	return type;
+    }
+
+  return NULL;
+}
+
 /* Search through the base classes of PARENT_TYPE for a symbol named
    NAME in block BLOCK.  */
 

gdb/cp-support.h

@@ -220,6 +220,11 @@ extern struct symbol *cp_lookup_nested_symbol (struct type *parent_type,
 
 struct type *cp_lookup_transparent_type (const char *name);
 
+/* See description in cp-namespace.c.  */
+
+struct type *find_type_baseclass_by_name (struct type *parent_type,
+					  const char *name);
+
 /* Functions from cp-name-parser.y.  */
 
 extern struct demangle_parse_info *cp_demangled_name_to_comp

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2013-11-25  Keith Seitz  <keiths@redhat.com>
+
+	PR c++/14819
+	* gdb.cp/impl-this.cc: New file.
+	* gdb.cp/impl-this.exp: New file.
+
 2013-11-25  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.perf/backtrace.c: New.

gdb/testsuite/gdb.cp/impl-this.cc

@@ -0,0 +1,135 @@
+/* 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/>.  */
+
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
+template <typename T>
+class A
+{
+public:
+  T i;
+  T z;
+  A () : i (1), z (10) {}
+};
+
+template <typename T>
+class B : public virtual A<T>
+{
+public:
+  T i;
+  T common;
+  B () : i (2), common (200) {}
+};
+
+typedef B<int> Bint;
+
+class C : public virtual A<int>
+{
+public:
+  int i;
+  int c;
+  int common;
+  C () : i (3), c (30), common (300) {}
+};
+
+class BB : public A<int>
+{
+public:
+  int i;
+  BB () : i (20) {}
+};
+
+class CC : public A<int>
+{
+public:
+  int i;
+  CC () : i (30) {}
+};
+
+class Ambig : public BB, public CC
+{
+public:
+  int i;
+  Ambig () : i (1000) {}
+};
+
+class D : public Bint, public C
+{
+public:
+  int i;
+  int x;
+  Ambig am;
+  D () : i (4), x (40) {}
+
+#ifdef DEBUG
+#define SUM(X)					\
+  do						\
+    {						\
+      sum += (X);				\
+      printf ("" #X " = %d\n", (X));		\
+    }						\
+  while (0)
+#else
+#define SUM(X) sum += (X)
+#endif
+
+int
+f (void)
+  {
+    int sum = 0;
+
+    SUM (i);
+    SUM (D::i);
+    SUM (D::B<int>::i);
+    SUM (B<int>::i);
+    SUM (D::C::i);
+    SUM (C::i);
+    SUM (D::B<int>::A<int>::i);
+    SUM (B<int>::A<int>::i);
+    SUM (A<int>::i);
+    SUM (D::C::A<int>::i);
+    SUM (C::A<int>::i);
+    SUM (D::x);
+    SUM (x);
+    SUM (D::C::c);
+    SUM (C::c);
+    SUM (c);
+    SUM (D::A<int>::i);
+    SUM (Bint::i);
+    //SUM (D::Bint::i);
+    //SUM (D::Bint::A<int>::i);
+    SUM (Bint::A<int>::i);
+    // ambiguous: SUM (common);
+    SUM (B<int>::common);
+    SUM (C::common);
+    SUM (am.i);
+    // ambiguous: SUM (am.A<int>::i);
+
+    return sum;
+  }
+};
+
+int
+main (void)
+{
+  Bint b;
+  D d;
+
+  return d.f () + b.i;
+}

gdb/testsuite/gdb.cp/impl-this.exp

@@ -0,0 +1,130 @@
+# 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/>.
+
+# This file is part of the gdb testsuite
+
+# Test expressions which assume an implicit "this" with a qualified
+# name.
+
+if {[skip_cplus_tests]} { continue }
+
+standard_testfile .cc
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+# First test expressions when there is no context.
+with_test_prefix "before run" {
+    gdb_test "print i" "No symbol \"i\" in current context."
+    gdb_test "print D::i" "Cannot reference non-static field \"i\""
+    gdb_test "print D::B<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print B<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print D::C::i" "Cannot reference non-static field \"i\""
+    gdb_test "print C::i" "Cannot reference non-static field \"i\""
+    gdb_test "print D::B<int>::A<int>::i" \
+	"Cannot reference non-static field \"i\""
+    gdb_test "print B<int>::A<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print A<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print D::C::A<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print C::A<int>::i" "Cannot reference non-static field \"i\""
+    gdb_test "print D::x" "Cannot reference non-static field \"x\""
+    gdb_test "print x" "No symbol \"x\" in current context."
+    gdb_test "print D::C::c" "Cannot reference non-static field \"c\""
+    gdb_test "print C::c" "Cannot reference non-static field \"c\""
+    gdb_test "print c" "No symbol \"c\" in current context."
+    gdb_test "print D::A<int>::i" "Cannot reference non-static field \"i\""
+}
+
+# Run to D::f.
+if {![runto_main]} {
+    perror "couldn't run to main"
+    continue
+}
+
+gdb_breakpoint "D::f"
+gdb_continue_to_breakpoint "continue to D::f"
+
+# Now test valid expressions in the class hierarchy for D.
+with_test_prefix "at D::f (valid expressions)" {
+    gdb_test "print i" "= 4"
+    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\"."
+    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\"."
+    gdb_test "print Bint::A<int>::i" "= 1"
+    gdb_test "print A<int>::i" "= 1"
+    gdb_test "print D::C::A<int>::i" "= 1"
+    gdb_test "print C::A<int>::i" "= 1"
+    gdb_test "print D::x" "= 40"
+    gdb_test "print x" "= 40"
+    gdb_test "print D::C::c" "= 30"
+    gdb_test "print C::c" "= 30"
+    gdb_test "print c" "= 30"
+    gdb_test "print D::A<int>::i" "= 1"
+}
+
+# Test some invalid 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\"."
+    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"
+    gdb_test "print Bint::c" "There is no field named c"
+    gdb_test "print Bint::A<int>::c" "There is no field named c"
+    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\"."
+    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"
+    gdb_test "print Bint::A<int>::x" "There is no field named x"
+    gdb_test "print D::C::x" "There is no field named x"
+    gdb_test "print C::x" "There is no field named x"
+    gdb_test "print D::C::A<int>::x" "There is no field named x"
+    gdb_test "print C::A<int>::x" "There is no field named x"
+}
+
+# Test some ambiguous names
+with_test_prefix "at D::f (ambiguous names)" {
+    gdb_test "print B<int>::common" " = 200"
+    gdb_test "print Bint::common" " = 200"
+    gdb_test "print C::common" " = 300"
+    gdb_test "print am.i" " = 1000"
+    gdb_test "print am.A<int>::i" \
+	"base class 'A<int>' is ambiguous in type 'Ambig'"
+    gdb_test "print am.BB::A<int>::i" \
+	"base class 'A<int>' is ambiguous in type 'Ambig'"
+    gdb_test "print am.CC::A<int>::i" \
+	"base class 'A<int>' is ambiguous in type 'Ambig'"
+}

gdb/valops.c

@@ -3128,10 +3128,35 @@ value_struct_elt_for_reference (struct type *domain, int offset,
 	    return value_from_longest
 	      (lookup_memberptr_type (TYPE_FIELD_TYPE (t, i), domain),
 	       offset + (LONGEST) (TYPE_FIELD_BITPOS (t, i) >> 3));
-	  else if (noside == EVAL_AVOID_SIDE_EFFECTS)
+	  else if (noside != EVAL_NORMAL)
 	    return allocate_value (TYPE_FIELD_TYPE (t, i));
 	  else
-	    error (_("Cannot reference non-static field \"%s\""), name);
+	    {
+	      /* Try to evaluate NAME as a qualified name with implicit
+		 this pointer.  In this case, attempt to return the
+		 equivalent to `this->*(&TYPE::NAME)'.  */
+	      v = value_of_this_silent (current_language);
+	      if (v != NULL)
+		{
+		  struct value *ptr;
+		  long mem_offset;
+		  struct type *type, *tmp;
+
+		  ptr = value_aggregate_elt (domain, name, NULL, 1, noside);
+		  type = check_typedef (value_type (ptr));
+		  gdb_assert (type != NULL
+			      && TYPE_CODE (type) == TYPE_CODE_MEMBERPTR);
+		  tmp = lookup_pointer_type (TYPE_DOMAIN_TYPE (type));
+		  v = value_cast_pointers (tmp, v, 1);
+		  mem_offset = value_as_long (ptr);
+		  tmp = lookup_pointer_type (TYPE_TARGET_TYPE (type));
+		  result = value_from_pointer (tmp,
+					       value_as_long (v) + mem_offset);
+		  return value_ind (result);
+		}
+
+	      error (_("Cannot reference non-static field \"%s\""), name);
+	    }
 	}
     }