PR 16253 revisited
Last year a patch was submitted/approved/commited to eliminate symbol_matches_domain which was causing this problem. It was later reverted because it introduced a (severe) performance regression. Recap: (gdb) list 1 enum e {A,B,C} e; 2 int main (void) { return 0; } 3 (gdb) p e Attempt to use a type name as an expression The parser attempts to find a symbol named "e" of VAR_DOMAIN. This gets passed down through lookup_symbol and (eventually) into block_lookup_symbol_primary, which iterates over the block's dictionary of symbols: for (sym = dict_iter_name_first (block->dict, name, &dict_iter); sym != NULL; sym = dict_iter_name_next (name, &dict_iter)) { if (symbol_matches_domain (SYMBOL_LANGUAGE (sym), SYMBOL_DOMAIN (sym), domain)) return sym; } The problem here is that we have a symbol named "e" in both STRUCT_DOMAIN and VAR_DOMAIN, and for languages like C++, Java, and Ada, where a tag name may be used as an implicit typedef of the type, symbol_matches_domain ignores the difference between VAR_DOMAIN and STRUCT_DOMAIN. As it happens, the STRUCT_DOMAIN symbol is found first, considered a match, and that symbol is returned to the parser, eliciting the (now dreaded) error message. Since this bug exists specifically because we have both STRUCT and VAR_DOMAIN symbols in a given block/CU, this patch rather simply/naively changes block_lookup_symbol_primary so that it continues to search for an exact domain match on the symbol if symbol_matches_domain returns a symbol which does not exactly match the requested domain. This "fixes" the immediate problem, but admittedly might uncover other, related bugs. [Paranoia?] However, it causes no regressions (functional or performance) in the test suite. A similar change has been made to block_lookup_symbol for other cases in which this bug might appear. The tests from the previous submission have been resurrected and updated. However since we can still be given a matching symbol with a different domain than requested, we cannot say that a symbol "was not found." The error messages today will still be the (dreaded) "Attempt to use a type name..." ChangeLog PR 16253 * block.c (block_lookup_symbol): For non-function blocks, continue to search for a symbol with an exact domain match Otherwise, return any previously found "best domain" symbol. (block_lookup_symbol_primary): Likewise. testsuite/ChangeLog PR 16253 * gdb.cp/var-tag-2.cc: New file. * gdb.cp/var-tag-3.cc: New file. * gdb.cp/var-tag-4.cc: New file. * gdb.cp/var-tag.cc: New file. * gdb.cp/var-tag.exp: New file.
This commit is contained in:
parent
fc637f04c7
commit
ee93cd5e1e
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@ -1,3 +1,12 @@
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2015-06-26 Keith Seitz <keiths@redhat.com>
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Doug Evans <dje@google.com>
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PR 16253
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* block.c (block_lookup_symbol): For non-function blocks,
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continue to search for a symbol with an exact domain match
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Otherwise, return any previously found "best domain" symbol.
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(block_lookup_symbol_primary): Likewise.
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2015-06-26 Patrick Palka <patrick@parcs.ath.cx>
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* NEWS: Mention the new option "history remove-duplicates".
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31
gdb/block.c
31
gdb/block.c
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@ -739,13 +739,21 @@ block_lookup_symbol (const struct block *block, const char *name,
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if (!BLOCK_FUNCTION (block))
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{
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struct symbol *other = NULL;
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ALL_BLOCK_SYMBOLS_WITH_NAME (block, name, iter, sym)
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{
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if (SYMBOL_DOMAIN (sym) == domain)
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return sym;
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/* This is a bit of a hack, but symbol_matches_domain might ignore
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STRUCT vs VAR domain symbols. So if a matching symbol is found,
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make sure there is no "better" matching symbol, i.e., one with
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exactly the same domain. PR 16253. */
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if (symbol_matches_domain (SYMBOL_LANGUAGE (sym),
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SYMBOL_DOMAIN (sym), domain))
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return sym;
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other = sym;
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}
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return NULL;
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return other;
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}
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else
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{
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@ -753,7 +761,10 @@ block_lookup_symbol (const struct block *block, const char *name,
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list; this loop makes sure to take anything else other than
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parameter symbols first; it only uses parameter symbols as a
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last resort. Note that this only takes up extra computation
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time on a match. */
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time on a match.
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It's hard to define types in the parameter list (at least in
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C/C++) so we don't do the same PR 16253 hack here that is done
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for the !BLOCK_FUNCTION case. */
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struct symbol *sym_found = NULL;
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@ -779,23 +790,31 @@ struct symbol *
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block_lookup_symbol_primary (const struct block *block, const char *name,
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const domain_enum domain)
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{
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struct symbol *sym;
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struct symbol *sym, *other;
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struct dict_iterator dict_iter;
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/* Verify BLOCK is STATIC_BLOCK or GLOBAL_BLOCK. */
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gdb_assert (BLOCK_SUPERBLOCK (block) == NULL
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|| BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) == NULL);
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other = NULL;
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for (sym = dict_iter_name_first (block->dict, name, &dict_iter);
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sym != NULL;
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sym = dict_iter_name_next (name, &dict_iter))
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{
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if (SYMBOL_DOMAIN (sym) == domain)
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return sym;
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/* This is a bit of a hack, but symbol_matches_domain might ignore
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STRUCT vs VAR domain symbols. So if a matching symbol is found,
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make sure there is no "better" matching symbol, i.e., one with
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exactly the same domain. PR 16253. */
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if (symbol_matches_domain (SYMBOL_LANGUAGE (sym),
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SYMBOL_DOMAIN (sym), domain))
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return sym;
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other = sym;
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}
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return NULL;
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return other;
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}
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/* See block.h. */
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@ -1,3 +1,13 @@
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2015-06-26 Keith Seitz <keiths@redhat.com>
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Doug Evans <dje@google.com>
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PR 16253
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* gdb.cp/var-tag-2.cc: New file.
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* gdb.cp/var-tag-3.cc: New file.
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* gdb.cp/var-tag-4.cc: New file.
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* gdb.cp/var-tag.cc: New file.
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* gdb.cp/var-tag.exp: New file.
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2015-06-26 Patrick Palka <patrick@parcs.ath.cx>
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* gdb.base/history-duplicates.exp: New test.
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@ -0,0 +1,22 @@
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/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* This object is in a separate file so that its debug info is not
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expanded at startup. Once debug info is expanded we are no longer
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exercising block_lookup_symbol, and instead are exercising
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block_lookup_symbol_primary. */
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enum E2 {a2, b2, c2} E2;
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@ -0,0 +1,22 @@
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/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* This object is in a separate file so that its debug info is not
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expanded at startup. Once debug info is expanded we are no longer
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exercising block_lookup_symbol, and instead are exercising
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block_lookup_symbol_primary. */
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struct S2 {} S2;
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@ -0,0 +1,22 @@
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/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* This object is in a separate file so that its debug info is not
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expanded at startup. Once debug info is expanded we are no longer
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exercising block_lookup_symbol, and instead are exercising
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block_lookup_symbol_primary. */
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union U2 {int a; char b;} U2;
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@ -0,0 +1,44 @@
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/* This testcase is part of GDB, the GNU debugger.
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Copyright 2014 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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int global = 3;
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class C {
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public:
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struct C1 {} C1;
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enum E1 {a1, b1, c1} E1;
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union U1 {int a1; char b1;} U1;
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C () : E1 (b1) {}
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void global (void) const {}
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int f (void) const { global (); return 0; }
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} C;
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struct S {} S;
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enum E {a, b, c} E;
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union U {int a; char b;} U;
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class CC {} cc;
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struct SS {} ss;
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enum EE {ea, eb, ec} ee;
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union UU {int aa; char bb;} uu;
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int
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main (void)
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{
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return C.f ();
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}
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@ -0,0 +1,105 @@
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# Copyright 2014, 2015 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# This file is part of the gdb testsuite
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# Test expressions in which variable names shadow tag names.
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if {[skip_cplus_tests]} { continue }
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standard_testfile var-tag.cc var-tag-2.cc var-tag-3.cc var-tag-4.cc
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if {[prepare_for_testing $testfile.exp $testfile \
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[list $srcfile $srcfile2 $srcfile3 $srcfile4] {debug c++}]} {
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return -1
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}
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proc do_global_tests {lang} {
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set invalid_print "Attempt to use a type name as an expression"
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set ptypefmt "type = (class|enum|union|struct) %s {.*}"
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with_test_prefix $lang {
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gdb_test_no_output "set language $lang"
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gdb_test "ptype C" "type = class C {.*}"
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gdb_test "print E" "= a"
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gdb_test "ptype E" "type = enum E {.*}"
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gdb_test "print S" "= {<No data fields>}"
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gdb_test "ptype S" "type = struct S {.*}"
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gdb_test "print U" "= {.*}"
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gdb_test "ptype U" "type = union U {.*}"
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gdb_test "print cc" "= {.*}"
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gdb_test "ptype cc" "type = class CC {.*}"
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gdb_test "print CC" [format $invalid_print "CC"]
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gdb_test "ptype CC" [format $ptypefmt "CC"]
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gdb_test "print ss" "= {<No data fields>}"
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gdb_test "ptype ss" "type = struct SS {.*}"
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gdb_test "print SS" [format $invalid_print "SS"]
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gdb_test "ptype SS" [format $ptypefmt "SS"]
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gdb_test "print ee" "= .*"
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gdb_test "ptype ee" "type = enum EE {.*}"
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gdb_test "print EE" [format $invalid_print "EE"]
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gdb_test "ptype EE" [format $ptypefmt "EE"]
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gdb_test "print uu" "= {.*}"
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gdb_test "ptype uu" "type = union UU {.*}"
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gdb_test "print UU" [format $invalid_print "UU"]
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gdb_test "ptype UU" [format $ptypefmt "UU"]
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# These tests exercise lookup of symbols using the "quick fns" API.
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# Each of them is in a separate CU as once its CU is expanded,
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# we're no longer using the quick fns API.
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gdb_test "print E2" "= a2"
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gdb_test "ptype E2" "type = enum E2 {.*}"
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gdb_test "print S2" "= {<No data fields>}"
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gdb_test "ptype S2" "type = struct S2 {.*}"
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gdb_test "print U2" "= {.*}"
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gdb_test "ptype U2" "type = union U2 {.*}"
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}
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}
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# First test expressions when there is no context.
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with_test_prefix "before start" {
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do_global_tests c++
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do_global_tests c
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}
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# Run to main and test again.
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if {![runto_main]} {
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perror "couldn't run to main"
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continue
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}
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with_test_prefix "in main" {
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do_global_tests c++
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do_global_tests c
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}
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# Run to C::f and test again.
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gdb_breakpoint "C::f"
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gdb_continue_to_breakpoint "continue to C::f"
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with_test_prefix "in C::f" {
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do_global_tests c++
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do_global_tests c
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}
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# Another hard-to-guess-the-users-intent bug...
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# It would be really nice if we could query the user!
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with_test_prefix "global collision" {
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gdb_test_no_output "set language c++"
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setup_kfail "c++/16463" "*-*-*"
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gdb_test "print global" "= 3"
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# ... with a simple workaround:
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gdb_test "print ::global" "= 3"
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}
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