| Summary: | [6/7 Regression] Supposedly-incompliant "error: '* key0' is not a constant expression" | ||
|---|---|---|---|
| Product: | gcc | Reporter: | sergey.ignatchenko |
| Component: | c++ | Assignee: | Jakub Jelinek <jakub> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | daniel.kruegler, webrown.cpp |
| Priority: | P2 | Keywords: | rejects-valid |
| Version: | 7.2.0 | ||
| Target Milestone: | 6.5 | ||
| Host: | Target: | ||
| Build: | Known to work: | 5.5.0 | |
| Known to fail: | 6.4.0, 7.3.0, 8.0.1 | Last reconfirmed: | 2018-04-16 00:00:00 |
| Attachments: | gcc8-pr84463.patch | ||
oops, forgot to mention command line: g++ -std=c++1z -lstdc++ -Werror ../chachatest.cpp where chachatest.cpp is provided in "CODE" section above Started to fail with r230365 ("Merge C++ delayed folding branch.") Created attachment 43948 [details] gcc8-pr84463.patch Untested fix. Author: jakub Date: Wed Apr 18 06:57:45 2018 New Revision: 259458 URL: https://gcc.gnu.org/viewcvs?rev=259458&root=gcc&view=rev Log: PR c++/84463 * typeck.c (cp_build_addr_expr_1): Move handling of offsetof-like tricks from here to ... * cp-gimplify.c (cp_fold) <case ADDR_EXPR>: ... here. Only use it if INDIRECT_REF's operand is INTEGER_CST cast to pointer type. * g++.dg/cpp0x/constexpr-nullptr-1.C: Add -O1 to dg-options. * g++.dg/cpp0x/constexpr-nullptr-2.C: Expect different diagnostics in two cases. Uncomment two other tests and add expected dg-error for them. * g++.dg/init/struct2.C: Cast to int rather than long to avoid -Wnarrowing diagnostics on some targets for c++11. * g++.dg/parse/array-size2.C: Remove xfail. * g++.dg/cpp0x/constexpr-84463.C: New test. Added: trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-84463.C Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/cp-gimplify.c trunk/gcc/cp/typeck.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-1.C trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-2.C trunk/gcc/testsuite/g++.dg/init/struct2.C trunk/gcc/testsuite/g++.dg/parse/array-size2.C Fixed for 8+. Not really sure if this patch should be backported. . Author: jakub Date: Fri Jun 22 21:12:32 2018 New Revision: 261956 URL: https://gcc.gnu.org/viewcvs?rev=261956&root=gcc&view=rev Log: Backported from mainline 2018-04-18 Jakub Jelinek <jakub@redhat.com> PR c++/84463 * typeck.c (cp_build_addr_expr_1): Move handling of offsetof-like tricks from here to ... * cp-gimplify.c (cp_fold) <case ADDR_EXPR>: ... here. Only use it if INDIRECT_REF's operand is INTEGER_CST cast to pointer type. * g++.dg/cpp0x/constexpr-nullptr-1.C: Add -O1 to dg-options. * g++.dg/cpp0x/constexpr-nullptr-2.C: Expect different diagnostics in two cases. Uncomment two other tests and add expected dg-error for them. * g++.dg/init/struct2.C: Cast to int rather than long to avoid -Wnarrowing diagnostics on some targets for c++11. * g++.dg/parse/array-size2.C: Remove xfail. * g++.dg/cpp0x/constexpr-84463.C: New test. Added: branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-84463.C Modified: branches/gcc-7-branch/gcc/cp/ChangeLog branches/gcc-7-branch/gcc/cp/cp-gimplify.c branches/gcc-7-branch/gcc/cp/typeck.c branches/gcc-7-branch/gcc/testsuite/ChangeLog branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-1.C branches/gcc-7-branch/gcc/testsuite/g++.dg/cpp0x/constexpr-nullptr-2.C branches/gcc-7-branch/gcc/testsuite/g++.dg/init/struct2.C branches/gcc-7-branch/gcc/testsuite/g++.dg/parse/array-size2.C |
== COMPILER ========== root@ubuntu-gcc7:~/ithare/kscope/test/nix# g++ --version g++ (Ubuntu 7.2.0-8ubuntu3) 7.2.0 Copyright (C) 2017 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. == CODE ============ #include <stdint.h> #include <cstddef> struct chacha_tv { const char *desc; const uint8_t key[32]; const uint8_t iv[8]; const size_t len; const unsigned char out[512]; }; static constexpr chacha_tv chacha_test_vectors[] = { { "TC1: All zero key and IV", { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, }, { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, }, 64, { 0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90, 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28, 0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a, 0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7, 0xda, 0x41, 0x59, 0x7c, 0x51, 0x57, 0x48, 0x8d, 0x77, 0x24, 0xe0, 0x3f, 0xb8, 0xd8, 0x4a, 0x37, 0x6a, 0x43, 0xb8, 0xf4, 0x15, 0x18, 0xa1, 0x1c, 0xc3, 0x87, 0xb6, 0x69, 0xb2, 0xee, 0x65, 0x86, }, }, }; constexpr int KSCOPE_CT_Chacha_set_key_iv2(const uint8_t* key0, int keybits /*128 or 256*/, const uint8_t iv0[8], const uint8_t counter0[8]) { uint8_t c = key0[0]; return 0; } constexpr static const chacha_tv* tv = &chacha_test_vectors[0]; constexpr static const int k = tv->key[0]; constexpr static uint8_t kk[3] = {0,1,2}; constexpr static int x0 = KSCOPE_CT_Chacha_set_key_iv2(chacha_test_vectors[0].key,256,tv->iv,nullptr);//OK constexpr static int x1 = KSCOPE_CT_Chacha_set_key_iv2(kk,256,tv->iv,nullptr);//OK constexpr static int x2 = KSCOPE_CT_Chacha_set_key_iv2(tv->key,256,tv->iv,nullptr); == PROBLEM ============ When trying to compile the code above with GCC 7.2, the following error is generated: ../chachatest.cpp:50:55: in constexpr expansion of 'KSCOPE_CT_Chacha_set_key_i v2(((const uint8_t*)(((const uint8_t (*)[32])tv) + 8)), 256, ((const uint8_t*)(( (const uint8_t (*)[8])tv) + 40)), 0)' ../chachatest.cpp:41:27: error: '* key0' is not a constant expression uint8_t c = key0[0]; Expected behaviour is to acknowledge that key0 is an 'address constant expression' in a sense of 5.19 (at least my humble reading of the standard says that it is), and to allow the code to be compiled. Notes: - note that both x0 and x1 compile ok - both Clang and MSVC seem to agree it is an 'address constant expression' and don't complain.