From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f48.google.com (mail-wr1-f48.google.com [209.85.221.48]) by sourceware.org (Postfix) with ESMTPS id C6BE7393C85F for ; Thu, 27 Aug 2020 18:02:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org C6BE7393C85F Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=palves.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=alves.ped@gmail.com Received: by mail-wr1-f48.google.com with SMTP id x7so6245974wro.3 for ; Thu, 27 Aug 2020 11:02:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id; bh=/97jeiN6QSPKbKL6ozqJWboP66fxu4Kv2QyRYOUJl7Y=; b=cE5/zcw5lozo0tSoZy+29NLjRzse1vpAG2FwhhvAkV9WU5kReZlgxnBql51sJ7mP3z OBvPwCcPPSjyb+xFbnsXUM1FnkoD3yzm+QTl1mwU1+2ogR1DObtl5iCSL3nYzRI0+yxr gEfoxEvnoucARZT3csKhccc8OY1ap3d4i3HvOKG5TinyUyQ3K/rMnQGtqJO5Tthqtt6N jMx8RenUTqbJZwGrFB8jTNTyvjfnx9Xha4UWZuCqk9AhrFjyuymvlJJj/nqP/hmWOuMq J+t8PQz8JBAf1sTO72l5BjrqqQV1SmzdPp9hgjDA1eyNBemP1JLvAzvUZMEYSx3fQHrS IVtw== X-Gm-Message-State: AOAM531hzpZwuigWaxcfudDhUPV6IkAbVojzRkffFPUM7UPgbwzD85FS N49MuQLl4+LGaAmoyjqznJyvXYNEaORb8Q== X-Google-Smtp-Source: ABdhPJwnI/Rj4jwJopLyg2OsquhRg8DSc1mbMgOM6GaLMxtAA1WjHijnhQPHxpGtgkZP2PjtpU9RaA== X-Received: by 2002:a5d:4c83:: with SMTP id z3mr21761243wrs.359.1598551373887; Thu, 27 Aug 2020 11:02:53 -0700 (PDT) Received: from localhost ([2001:8a0:f905:5600:56ee:75ff:fe8d:232b]) by smtp.gmail.com with ESMTPSA id b204sm7228795wmd.34.2020.08.27.11.02.52 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 27 Aug 2020 11:02:52 -0700 (PDT) From: Pedro Alves To: gdb-patches@sourceware.org Subject: [PATCH] Reject ambiguous C++ field accesses Date: Thu, 27 Aug 2020 19:02:51 +0100 Message-Id: <20200827180251.20244-1-pedro@palves.net> X-Mailer: git-send-email 2.14.5 X-Spam-Status: No, score=-8.0 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM, GIT_PATCH_0, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SCC_5_SHORT_WORD_LINES, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Aug 2020 18:03:00 -0000 The gdb.cp/ambiguous.exp testcase had been disabled for many years, but recently it was re-enabled. However, it is failing everywhere. That is because it is testing an old feature that is gone from GDB. The testcase is expecting to see an ambiguous field warning, like: # X is derived from A1 and A2; both A1 and A2 have a member 'x' send_gdb "print x.x\n" gdb_expect { -re "warning: x ambiguous; using X::A2::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { pass "print x.x" } -re "warning: x ambiguous; using X::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { pass "print x.x" } -re ".*$gdb_prompt $" { fail "print x.x" } timeout { fail "(timeout) print x.x" } } However, GDB just accesses one of the candidates without warning or error: print x.x $1 = 1431655296 (gdb) FAIL: gdb.cp/ambiguous.exp: print x.x (The weird number is because the testcase does not initialize the variables.) The testcase come in originally with the big HP merge: +Sun Jan 10 23:44:11 1999 David Taylor + + + The following files are part of the HP merge; some had longer + names at HP, but have been renamed to be no more than 14 + characters in length. Looking at the tree back then, we find that warning: /* Helper function used by value_struct_elt to recurse through baseclasses. Look for a field NAME in ARG1. Adjust the address of ARG1 by OFFSET bytes, and search in it assuming it has (class) type TYPE. If found, return value, else return NULL. If LOOKING_FOR_BASECLASS, then instead of looking for struct fields, look for a baseclass named NAME. */ static value_ptr search_struct_field (name, arg1, offset, type, looking_for_baseclass) char *name; register value_ptr arg1; int offset; register struct type *type; int looking_for_baseclass; { int found = 0; char found_class[1024]; value_ptr v; struct type *vbase = NULL; found_class[0] = '\000'; v = search_struct_field_aux (name, arg1, offset, type, looking_for_baseclass, &found, found_class, &vbase); if (found > 1) warning ("%s ambiguous; using %s::%s. Use a cast to disambiguate.", name, found_class, name); return v; } However, in current GDB, search_struct_field does not handle the ambiguous field case, nor is that warning found anywhere. Somehow it got lost over the years. That seems like a regression, because the compiler (as per language rules) rejects the ambiguous accesses as well. E.g.: gdb.cp/ambiguous.cc:98:5: error: request for member 'x' is ambiguous 98 | x.x = 1; | ^ gdb.cp/ambiguous.cc:10:7: note: candidates are: 'int A2::x' 10 | int x; | ^ gdb.cp/ambiguous.cc:4:7: note: 'int A1::x' 4 | int x; | ^ This patch restores the feature, though implemented differently and with better user experience, IMHO. An ambiguous access is now an error instead of a warning, and also GDB shows you the all candidates, like: (gdb) print x.x Request for member 'x' is ambiguous in type 'X'. Candidates are: 'int A1::x' (X -> A1) 'int A2::x' (X -> A2) (gdb) print j.x Request for member 'x' is ambiguous in type 'J'. Candidates are: 'int A1::x' (J -> K -> A1) 'int A1::x' (J -> L -> A1) Users can then fix their commands by casting or by specifying the baseclass explicitly, like: (gdb) p x.A1::x $1 = 1 (gdb) p x.A2::x $2 = 2 (gdb) p ((A1) x).x $3 = 1 (gdb) p ((A2) x).x $4 = 2 (gdb) p j.K::x $12 = 1 (gdb) p j.L::x $13 = 2 (gdb) p j.A1::x base class 'A1' is ambiguous in type 'J' The last error I've not touched; could be improved to also list the baseclass candidates. The showing the class "path" for each candidate was inspired by GCC's output when you try an ambiguous cast: gdb.cp/ambiguous.cc:161:8: error: ambiguous conversion from derived class 'const JVA1' to base class 'const A1': class JVA1 -> class KV -> class A1 class JVA1 -> class A1 (A1) jva1; ^~~~ I did not include the "class" word as it seemed unnecessarily repetitive, but I can include it if people prefer it: (gdb) print j.x Request for member 'x' is ambiguous in type 'J'. Candidates are: 'int A1::x' (class J -> class K -> class A1) 'int A1::x' (class J -> class L -> class A1) The testcase is adjusted accordingly. I also took the chance to modernize it at the same time. Also, as mentioned above, the testcase doesn't currently initialize the tested variables. This patch inializes them all, giving each field a distinct value, so that we can be sure that GDB is accessing the right fields / offsets. The testcase is extended accordingly. Unfortunately, this exposes some bugs, not addressed in this patch. The bug is around a class that inherits from A1 directly and also inherits from with two other distinct base classes that inherit virtually from A1 in turn: print jva1.KV::x $51 = 1431665544 (gdb) FAIL: gdb.cp/ambiguous.exp: all fields: print jva1.KV::x print jva1.KV::y $52 = 21845 (gdb) FAIL: gdb.cp/ambiguous.exp: all fields: print jva1.KV::y This shows how GDB is clearly reading the confusing the offset of the _vptr.KV with the A1 offset: (gdb) print /x jva1 $1 = { = { = {x = 0x2, y = 0x16}, _vptr.KV = 0x555555557b88 , i = 0x457}, ......} ^^^^^^^^^^^^^^ (gdb) print /x jva1.KV::x $2 = 0x55557b88 ^^^^^^^^^^ (gdb) print /x jva1.KV::y $3 = 0x5555 ^^^^^^ (gdb) print /x (KV)jva1 $4 = { = , _vptr.KV = 0x555555557b88 , i = 0x457} (gdb) print /x (A1)(KV)jva1 Cannot access memory at address 0x0 Since that's an orthogonal issue, I'm kfailing the tests that fail because of it. (I'll file a bug soon, unless someone can fix it quickly!) gdb/ChangeLog: * valops.c (struct struct_field_searcher): New. (update_search_result): Rename to ... (struct_field_searcher::update_result): ... this. Simplify prototype. Record all found fields. (do_search_struct_field): Rename to ... (struct_field_searcher::search): ... this. Simplify prototype. Maintain stack of visited baseclass path. Call update_result for fields too. Keep searching fields in baseclasses instead of stopping at the first found field. (search_struct_field): Use struct_field_searcher. When looking for fields, report ambiguous access attempts. gdb/testsuite/ChangeLog: * gdb.cp/ambiguous.cc (marker1): Delete. (main): Initialize all the fields of the locals. Replace marker1 call with a "set breakpoint here" marker. * gdb.cp/ambiguous.exp: Modernize. Use gdb_continue_to_breakpoint instead of running to marker1. Add tests printing all the variables and all the fields of the variables. (test_ambiguous): New proc, expecting the new GDB output when a field access is ambiguous. Change all "warning: X ambiguous" tests to use it. --- gdb/testsuite/gdb.cp/ambiguous.cc | 87 ++++++++-- gdb/testsuite/gdb.cp/ambiguous.exp | 321 +++++++++++++++++++++---------------- gdb/valops.c | 219 ++++++++++++++++++------- 3 files changed, 418 insertions(+), 209 deletions(-) diff --git a/gdb/testsuite/gdb.cp/ambiguous.cc b/gdb/testsuite/gdb.cp/ambiguous.cc index 6ee7bc18ea9..a55686547f2 100644 --- a/gdb/testsuite/gdb.cp/ambiguous.cc +++ b/gdb/testsuite/gdb.cp/ambiguous.cc @@ -1,9 +1,4 @@ -void marker1() -{ - return; -} - class A1 { public: int x; @@ -102,9 +97,81 @@ int main() i += k.i + m.w + a1.x + a2.x + a3.x + x.z + l.z + n.r + j.j; - marker1(); - + /* Initialize all the fields. Keep the order the same as in the + .exp file. */ + + a1.x = 1; + a1.y = 2; + + a2.x = 1; + a2.y = 2; + + a3.x = 1; + a3.y = 2; + + x.A1::x = 1; + x.A1::y = 2; + x.A2::x = 3; + x.A2::y = 4; + x.z = 5; + + l.x = 1; + l.y = 2; + l.z = 3; + + m.x = 1; + m.y = 2; + m.w = 3; + + n.A1::x = 1; + n.A1::y = 2; + n.A2::x = 3; + n.A2::y = 4; + n.w = 5; + n.r = 6; + n.z = 7; + + k.x = 1; + k.y = 2; + k.i = 3; + + j.K::x = 1; + j.K::y = 2; + j.L::x = 3; + j.L::y = 4; + j.i = 5; + j.z = 6; + j.j = 7; + + jv.x = 1; + jv.y = 2; + jv.i = 3; + jv.z = 4; + jv.jv = 5; + + jva1.KV::x = 1; + jva1.KV::y = 2; + jva1.LV::x = 3; + jva1.LV::y = 4; + jva1.z = 5; + jva1.i = 6; + jva1.jva1 = 7; + + jva2.KV::x = 1; + jva2.KV::y = 2; + jva2.LV::x = 3; + jva2.LV::y = 4; + jva2.A2::x = 5; + jva2.A2::y = 6; + jva2.z = 7; + jva2.i = 8; + jva2.jva2 = 9; + + jva1v.x = 1; + jva1v.y = 2; + jva1v.z = 3; + jva1v.i = 4; + jva1v.jva1v = 5; + + return 0; /* set breakpoint here */ } - - - diff --git a/gdb/testsuite/gdb.cp/ambiguous.exp b/gdb/testsuite/gdb.cp/ambiguous.exp index 17fb29f5350..74783cd0725 100644 --- a/gdb/testsuite/gdb.cp/ambiguous.exp +++ b/gdb/testsuite/gdb.cp/ambiguous.exp @@ -15,15 +15,9 @@ # This file is part of the gdb testsuite -# tests relating to ambiguous class members -# Written by Satish Pai 1997-07-28 - -# This file is part of the gdb testsuite - -# -# test running programs -# - +# Print out various class objects' members and check that the error +# about the field or baseclass being ambiguious is emitted at the +# right times. if { [skip_cplus_tests] } { continue } @@ -47,180 +41,225 @@ if {[prepare_for_testing "failed to prepare" $testfile $srcfile \ return -1 } -# -# set it up at a breakpoint so we can play with the variable values -# +# Set it up at a breakpoint so we can play with the variable values. + if ![runto_main] then { perror "couldn't run to breakpoint" continue } -send_gdb "break marker1\n" ; gdb_expect -re ".*$gdb_prompt $" - send_gdb "cont\n" - gdb_expect { - -re "Break.* marker1 \\(\\) at .*:$decimal.*$gdb_prompt $" { - send_gdb "up\n" - gdb_expect { - -re ".*$gdb_prompt $" { pass "up from marker1" } - timeout { fail "up from marker1" } - } - } - -re "$gdb_prompt $" { fail "continue to marker1" } - timeout { fail "(timeout) continue to marker1" } +set lineno [gdb_get_line_number "set breakpoint here"] + +gdb_breakpoint $lineno +gdb_continue_to_breakpoint "breakpoint here" + +set number -?$decimal + +with_test_prefix "all vars" { + gdb_test "print a1" \ + " = \{x = 1, y = 2\}" + + gdb_test "print a2" \ + " = \{x = 1, y = 2\}" + + gdb_test "print a3" \ + " = \{x = 1, y = 2\}" + + gdb_test "print x" \ + " = \{ = \{x = 1, y = 2\}, = \{x = 3, y = 4\}, z = 5\}" + + gdb_test "print l" \ + " = \{ = \{x = 1, y = 2\}, z = 3\}" + + gdb_test "print m" \ + " = \{ = \{x = 1, y = 2\}, w = 3\}" + + gdb_test "print n" \ + " = \{ = \{ = \{x = 1, y = 2\}, z = 7\}, = \{ = \{x = 3, y = 4\}, w = 5\}, r = 6\}" + + gdb_test "print k" \ + " = \{ = \{x = 1, y = 2\}, i = 3\}" + + gdb_test "print j" \ + " = { = { = {x = 1, y = 2}, i = 5}, = { = {x = 3, y = 4}, z = 6}, j = 7}" + + gdb_test "print jv" \ + " = \{ = \{ = \{x = 1, y = 2\}, _vptr.KV = $hex , i = 3\}, = \{_vptr.LV = $hex , z = 4\}, jv = 5\}" + + # No way to initialize one of the A1's, so just take any number there. + gdb_test "print jva1" \ + " = \{ = \{ = \{x = 3, y = 4\}, _vptr.KV = $hex , i = 6\}, = \{_vptr.LV = $hex , z = 5\}, = \{x = $number, y = $number\}, jva1 = 7\}" + + gdb_test "print jva2" \ + " = \{ = \{ = \{x = 3, y = 4\}, _vptr.KV = $hex , i = 8\}, = \{_vptr.LV = $hex , z = 7\}, = \{x = 5, y = 6\}, jva2 = 9\}" + + gdb_test "print jva1v" \ + " = \{ = \{ = \{x = 1, y = 2\}, _vptr.KV = $hex , i = 4\}, = \{_vptr.LV = $hex , z = 3\}, jva1v = 5\}" +} + +# Check that we can access all the fields correctly, using the same +# syntax as used in the .cc file. Keep the order here in sync with +# the .cc file. +with_test_prefix "all fields" { + gdb_test "print a1.x" " = 1" + gdb_test "print a1.y" " = 2" + + gdb_test "print a2.x" " = 1" + gdb_test "print a2.y" " = 2" + + gdb_test "print a3.x" " = 1" + gdb_test "print a3.y" " = 2" + + gdb_test "print x.A1::x" " = 1" + gdb_test "print x.A1::y" " = 2" + gdb_test "print x.A2::x" " = 3" + gdb_test "print x.A2::y" " = 4" + gdb_test "print x.z" " = 5" + + gdb_test "print l.x" " = 1" + gdb_test "print l.y" " = 2" + gdb_test "print l.z" " = 3" + + gdb_test "print m.x" " = 1" + gdb_test "print m.y" " = 2" + gdb_test "print m.w" " = 3" + + gdb_test "print n.A1::x" " = 1" + gdb_test "print n.A1::y" " = 2" + gdb_test "print n.A2::x" " = 3" + gdb_test "print n.A2::y" " = 4" + gdb_test "print n.w" " = 5" + gdb_test "print n.r" " = 6" + gdb_test "print n.z" " = 7" + + gdb_test "print k.x" " = 1" + gdb_test "print k.y" " = 2" + gdb_test "print k.i" " = 3" + + gdb_test "print j.K::x" " = 1" + gdb_test "print j.K::y" " = 2" + gdb_test "print j.L::x" " = 3" + gdb_test "print j.L::y" " = 4" + gdb_test "print j.i" " = 5" + gdb_test "print j.z" " = 6" + gdb_test "print j.j" " = 7" + + gdb_test "print jv.x" " = 1" + gdb_test "print jv.y" " = 2" + gdb_test "print jv.i" " = 3" + gdb_test "print jv.z" " = 4" + gdb_test "print jv.jv" " = 5" + + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva1.KV::x" " = 1" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva1.KV::y" " = 2" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva1.LV::x" " = 3" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva1.LV::y" " = 4" + gdb_test "print jva1.z" " = 5" + gdb_test "print jva1.i" " = 6" + gdb_test "print jva1.jva1" "= 7" + + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva2.KV::x" " = 1" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva2.KV::y" " = 2" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva2.LV::x" " = 3" + setup_kfail "gdb/nnnnn" *-*-* + gdb_test "print jva2.LV::y" " = 4" + gdb_test "print jva2.A2::x" " = 5" + gdb_test "print jva2.A2::y" " = 6" + gdb_test "print jva2.z" " = 7" + gdb_test "print jva2.i" " = 8" + gdb_test "print jva2.jva2" "= 9" + + gdb_test "print jva1v.x" " = 1" + gdb_test "print jva1v.y" " = 2" + gdb_test "print jva1v.z" " = 3" + gdb_test "print jva1v.i" " = 4" + gdb_test "print jva1v.jva1v" " = 5" +} + +# Test that printing WHAT reports an error about FIELD being ambiguous +# in TYPE, and that the candidates are CANDIDATES. +proc test_ambiguous {what field type candidates} { + set msg "Request for member '$field' is ambiguous in type '$type'. Candidates are:" + + foreach c $candidates { + set c_re [string_to_regexp $c] + append msg "\r\n $c_re" } -# print out various class objects' members. The values aren't -# important, just check that the warning is emitted at the -# right times. + gdb_test "print $what" $msg +} # X is derived from A1 and A2; both A1 and A2 have a member 'x' -send_gdb "print x.x\n" -gdb_expect { - -re "warning: x ambiguous; using X::A2::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print x.x" - } - -re "warning: x ambiguous; using X::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print x.x" - } - -re ".*$gdb_prompt $" { fail "print x.x" } - timeout { fail "(timeout) print x.x" } +test_ambiguous "x.x" "x" "X" { + "'int A1::x' (X -> A1)" + "'int A2::x' (X -> A2)" } - # N is derived from A1 and A2, but not immediately -- two steps # up in the hierarchy. Both A1 and A2 have a member 'x'. -send_gdb "print n.x\n" -gdb_expect { - -re "warning: x ambiguous; using N::M::A2::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print n.x" - } - -re "warning: x ambiguous; using N::L::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print n.x" - } - -re ".*$gdb_prompt $" { fail "print n.x" } - timeout { fail "(timeout) print n.x" } +test_ambiguous "n.x" "x" "N" { + "'int A1::x' (N -> L -> A1)" + "'int A2::x' (N -> M -> A2)" } -# J is derived from A1 twice. A1 has a member x. -send_gdb "print j.x\n" -gdb_expect { - -re "warning: x ambiguous; using J::L::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print j.x" - } - -re "warning: x ambiguous; using J::K::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print j.x" - } - -re ".*$gdb_prompt $" { fail "print j.x" } - timeout { fail "(timeout) print j.x" } +# J is derived from A1 twice. A1 has a member x. +test_ambiguous "j.x" "x" "J" { + "'int A1::x' (J -> K -> A1)" + "'int A1::x' (J -> L -> A1)" } # JV is derived from A1 but A1 is a virtual base. Should not -# report an ambiguity in this case. -send_gdb "print jv.x\n" -gdb_expect { - -re "warning: x ambiguous.*Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - fail "print jv.x (ambiguity reported)" - } - -re "\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { pass "print jv.x" } - -re ".*$gdb_prompt $" { fail "print jv.x (??)" } - timeout { fail "(timeout) print jv.x" } -} +# report an ambiguity in this case. +gdb_test "print jv.x" " = 1" # JVA1 is derived from A1; A1 occurs as a virtual base in two # ancestors, and as a non-virtual immediate base. Ambiguity must -# be reported. -send_gdb "print jva1.x\n" -gdb_expect { - -re "warning: x ambiguous; using JVA1::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print jva1.x" - } - -re "warning: x ambiguous; using JVA1::KV::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print jva1.x" - } - -re ".*$gdb_prompt $" { fail "print jva1.x" } - timeout { fail "(timeout) print jva1.x" } +# be reported. +test_ambiguous "jva1.x" "x" "JVA1" { + "'int A1::x' (JVA1 -> KV -> A1)" + "'int A1::x' (JVA1 -> A1)" } # JVA2 is derived from A1 & A2; A1 occurs as a virtual base in two # ancestors, and A2 is a non-virtual immediate base. Ambiguity must # be reported as A1 and A2 both have a member 'x'. -send_gdb "print jva2.x\n" -gdb_expect { - -re "warning: x ambiguous; using JVA2::A2::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print jva2.x" - } - -re "warning: x ambiguous; using JVA2::KV::A1::x. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - pass "print jva2.x" - } - -re ".*$gdb_prompt $" { fail "print jva2.x" } - timeout { fail "(timeout) print jva2.x" } +test_ambiguous "jva2.x" "x" "JVA2" { + "'int A1::x' (JVA2 -> KV -> A1)" + "'int A2::x' (JVA2 -> A2)" } # JVA1V is derived from A1; A1 occurs as a virtual base in two # ancestors, and also as a virtual immediate base. Ambiguity must # not be reported. -send_gdb "print jva1v.x\n" -gdb_expect { - -re "warning: x ambiguous.*Use a cast to disambiguate.\r\n\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { - fail "print jva1v.x (ambiguity reported)" - } - -re "\\$\[0-9\]* = \[-\]*\[0-9\]*\r\n$gdb_prompt $" { pass "print jva1v.x" } - -re ".*$gdb_prompt $" { fail "print jva1v.x (??)" } - timeout { fail "(timeout) print jva1v.x" } -} +gdb_test "print jva1v.x" " = 1" # Now check for ambiguous bases. # J is derived from A1 twice; report ambiguity if a J is # cast to an A1. -send_gdb "print (A1)j\n" -gdb_expect { - -re "warning: A1 ambiguous; using J::L::A1. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - pass "print (A1)j" - } - -re "warning: A1 ambiguous; using J::K::A1. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - pass "print (A1)j" - } - -re ".*$gdb_prompt $" { fail "print (A1)j" } - timeout { fail "(timeout) print (A1)j" } -} +gdb_test "print (A1)j" "base class 'A1' is ambiguous in type 'J'" # JV is derived from A1 twice, but A1 is a virtual base; should # not report ambiguity when a JV is cast to an A1. -send_gdb "print (A1)jv\n" -gdb_expect { - -re "warning: A1 ambiguous.*Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - fail "print (A1)jv (ambiguity reported)" - } - -re "\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { pass "print (A1)jv" } - -re ".*$gdb_prompt $" { fail "print (A1)jv (??)" } - timeout { fail "(timeout) print (A1)jv" } -} +gdb_test "print (A1)jv" " = {x = 1, y = 2}" # JVA1 is derived from A1; A1 is a virtual base and also a # non-virtual base. Must report ambiguity if a JVA1 is cast to an A1. -send_gdb "print (A1)jva1\n" -gdb_expect { - -re "warning: A1 ambiguous; using JVA1::A1. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - pass "print (A1)jva1" - } - -re "warning: A1 ambiguous; using JVA1::KV::A1. Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - pass "print (A1)jva1" - } - -re ".*$gdb_prompt $" { fail "print (A1)jva1" } - timeout { fail "(timeout) print (A1)jva1" } -} +gdb_test "print (A1)jva1" "base class 'A1' is ambiguous in type 'JVA1'" + +# Add an intermediate cast to KV, and it should work. +setup_kfail "gdb/nnnnn" *-*-* +gdb_test "print (KV)jva1" " = \{ = \{x = 3, y = 4\}, _vptr.KV = $hex , i = 6\}" +setup_kfail "gdb/nnnnn" *-*-* +gdb_test "print (A1)(KV)jva1" " = \{x = 3, y = 4\}" # JVA1V is derived from A1; A1 is a virtual base indirectly # and also directly; must not report ambiguity when a JVA1V is cast to an A1. -send_gdb "print (A1)jva1v\n" -gdb_expect { - -re "warning: A1 ambiguous.*Use a cast to disambiguate.\r\n\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { - fail "print (A1)jva1v (ambiguity reported)" - } - -re "\\$\[0-9\]* = \{x = \[-\]*\[0-9\]*, y = \[-\]*\[0-9\]*\}\r\n$gdb_prompt $" { pass "print (A1)jva1v" - } - -re ".*$gdb_prompt $" { fail "print (A1)jva1v (??)" } - timeout { fail "(timeout) print (A1)jva1v" } -} - +gdb_test "print (A1)jva1v" " = {x = 1, y = 2}" diff --git a/gdb/valops.c b/gdb/valops.c index 0eb2b096211..0e030a03ecd 100644 --- a/gdb/valops.c +++ b/gdb/valops.c @@ -1766,25 +1766,105 @@ typecmp (int staticp, int varargs, int nargs, return i + 1; } -/* Helper class for do_search_struct_field that updates *RESULT_PTR - and *LAST_BOFFSET, and possibly throws an exception if the field - search has yielded ambiguous results. */ +/* Helper class for search_struct_field that keeps track of found + results. See search_struct_field for description of + LOOKING_FOR_BASECLASS. If LOOKING_FOR_BASECLASS is true, possibly + throws an exception if the base class search has yielded ambiguous + results. If LOOKING_FOR_BASECLASS is false, found fields are + accumulated and the caller (search_struct_field takes) care of + throwing an error if the field search yielded ambiguous results. + The latter is done that way so that the error message can include a + list of all the found candidates. */ + +struct struct_field_searcher +{ + /* A found field. */ + struct found_field + { + /* Patch to the structure where the field was found. */ + std::vector path; + + /* The field found. */ + struct value *field_value; + }; + + struct_field_searcher (const char *name, + struct type *outermost_type, + bool looking_for_baseclass) + : m_name (name), + m_looking_for_baseclass (looking_for_baseclass), + m_outermost_type (outermost_type) + { + } -static void -update_search_result (struct value **result_ptr, struct value *v, - LONGEST *last_boffset, LONGEST boffset, - const char *name, struct type *type) + void search (struct value *arg1, LONGEST offset, + struct type *type); + + const std::vector &fields () + { + return m_fields; + } + + struct value *baseclass () + { + return m_baseclass; + } + +private: + /* Update results to include V, a found field/baseclass. */ + void update_result (struct value *v, LONGEST boffset); + + /* The name of the field/baseclass we're searching for. */ + const char *m_name; + + /* Whether we're looking for a baseclass, or a field. */ + const bool m_looking_for_baseclass; + + /* The offset of base class containing the field/baseclass we last + recorded. */ + LONGEST m_last_boffset = 0; + + /* If looking for a baseclass, then the result is stored here. */ + struct value *m_baseclass = nullptr; + + /* When looking for fields, the found candidates are stored + here. */ + std::vector m_fields; + + /* The type of the initial type passed to search_struct_field; this + is used for error reporting when the lookup is ambiguous. */ + struct type *m_outermost_type; + + /* The full path to the struct being inspected. E.g. for field 'x' + defined in class B inherited by class A, we have A and B pushed + on the path. */ + std::vector m_struct_path; +}; + +void +struct_field_searcher::update_result (struct value *v, LONGEST boffset) { if (v != NULL) { - if (*result_ptr != NULL - /* The result is not ambiguous if all the classes that are - found occupy the same space. */ - && *last_boffset != boffset) - error (_("base class '%s' is ambiguous in type '%s'"), - name, TYPE_SAFE_NAME (type)); - *result_ptr = v; - *last_boffset = boffset; + if (m_looking_for_baseclass) + { + if (m_baseclass != nullptr + /* The result is not ambiguous if all the classes that are + found occupy the same space. */ + && m_last_boffset != boffset) + error (_("base class '%s' is ambiguous in type '%s'"), + m_name, TYPE_SAFE_NAME (m_outermost_type)); + + m_baseclass = v; + m_last_boffset = boffset; + } + else + { + /* The field is not ambiguous if it occupies the same + space. */ + if (m_fields.empty () || m_last_boffset != boffset) + m_fields.push_back ({m_struct_path, v}); + } } } @@ -1795,25 +1875,25 @@ update_search_result (struct value **result_ptr, struct value *v, search_struct_field; this is used for error reporting when the lookup is ambiguous. */ -static void -do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, - struct type *type, int looking_for_baseclass, - struct value **result_ptr, - LONGEST *last_boffset, - struct type *outermost_type) +void +struct_field_searcher::search (struct value *arg1, LONGEST offset, + struct type *type) { int i; int nbases; + m_struct_path.push_back (type); + SCOPE_EXIT { m_struct_path.pop_back (); }; + type = check_typedef (type); nbases = TYPE_N_BASECLASSES (type); - if (!looking_for_baseclass) + if (!m_looking_for_baseclass) for (i = type->num_fields () - 1; i >= nbases; i--) { const char *t_field_name = TYPE_FIELD_NAME (type, i); - if (t_field_name && (strcmp_iw (t_field_name, name) == 0)) + if (t_field_name && (strcmp_iw (t_field_name, m_name) == 0)) { struct value *v; @@ -1821,7 +1901,8 @@ do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, v = value_static_field (type, i); else v = value_primitive_field (arg1, offset, i, type); - *result_ptr = v; + + update_result (v, offset); return; } @@ -1845,7 +1926,6 @@ do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, represented as a struct, with a member for each . */ - struct value *v = NULL; LONGEST new_offset = offset; /* This is pretty gross. In G++, the offset in an @@ -1859,16 +1939,7 @@ do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, && TYPE_FIELD_BITPOS (field_type, 0) == 0)) new_offset += TYPE_FIELD_BITPOS (type, i) / 8; - do_search_struct_field (name, arg1, new_offset, - field_type, - looking_for_baseclass, &v, - last_boffset, - outermost_type); - if (v) - { - *result_ptr = v; - return; - } + search (arg1, new_offset, field_type); } } } @@ -1880,10 +1951,10 @@ do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, /* If we are looking for baseclasses, this is what we get when we hit them. But it could happen that the base part's member name is not yet filled in. */ - int found_baseclass = (looking_for_baseclass + int found_baseclass = (m_looking_for_baseclass && TYPE_BASECLASS_NAME (type, i) != NULL - && (strcmp_iw (name, - TYPE_BASECLASS_NAME (type, + && (strcmp_iw (m_name, + TYPE_BASECLASS_NAME (type, i)) == 0)); LONGEST boffset = value_embedded_offset (arg1) + offset; @@ -1924,28 +1995,17 @@ do_search_struct_field (const char *name, struct value *arg1, LONGEST offset, if (found_baseclass) v = v2; else - { - do_search_struct_field (name, v2, 0, - TYPE_BASECLASS (type, i), - looking_for_baseclass, - result_ptr, last_boffset, - outermost_type); - } + search (v2, 0, TYPE_BASECLASS (type, i)); } else if (found_baseclass) v = value_primitive_field (arg1, offset, i, type); else { - do_search_struct_field (name, arg1, - offset + TYPE_BASECLASS_BITPOS (type, - i) / 8, - basetype, looking_for_baseclass, - result_ptr, last_boffset, - outermost_type); + search (arg1, offset + TYPE_BASECLASS_BITPOS (type, i) / 8, + basetype); } - update_search_result (result_ptr, v, last_boffset, - boffset, name, outermost_type); + update_result (v, boffset); } } @@ -1960,12 +2020,55 @@ static struct value * search_struct_field (const char *name, struct value *arg1, struct type *type, int looking_for_baseclass) { - struct value *result = NULL; - LONGEST boffset = 0; + struct_field_searcher searcher (name, type, looking_for_baseclass); - do_search_struct_field (name, arg1, 0, type, looking_for_baseclass, - &result, &boffset, type); - return result; + searcher.search (arg1, 0, type); + + if (!looking_for_baseclass) + { + const auto &fields = searcher.fields (); + + if (fields.empty ()) + return nullptr; + else if (fields.size () > 1) + { + std::string candidates; + + for (auto &&candidate : fields) + { + gdb_assert (!candidate.path.empty ()); + + struct type *field_type = value_type (candidate.field_value); + struct type *struct_type = candidate.path.back (); + + std::string path; + bool first = true; + for (struct type *t : candidate.path) + { + if (first) + first = false; + else + path += " -> "; + path += t->name (); + } + + candidates += string_printf ("\n '%s %s::%s' (%s)", + TYPE_SAFE_NAME (field_type), + TYPE_SAFE_NAME (struct_type), + name, + path.c_str ()); + } + + error (_("Request for member '%s' is ambiguous in type '%s'." + " Candidates are:%s"), + name, TYPE_SAFE_NAME (type), + candidates.c_str ()); + } + else + return fields[0].field_value; + } + else + return searcher.baseclass (); } /* Helper function used by value_struct_elt to recurse through base-commit: 8c51f2f291a5459e1eabd000b2c52e5de52b4c56 -- 2.14.5