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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id b2-20020ac86bc2000000b003b7e8c04d2esm5336917qtt.64.2023.02.05.06.57.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Feb 2023 06:57:37 -0800 (PST) From: Patrick Palka X-Google-Original-From: Patrick Palka Date: Sun, 5 Feb 2023 09:57:36 -0500 (EST) To: Jason Merrill cc: Patrick Palka , gcc-patches@gcc.gnu.org Subject: Re: [PATCH] c++: equivalence of non-dependent calls [PR107461] In-Reply-To: <03f75252-861b-528e-df42-6a88adddb388@redhat.com> Message-ID: <645edbe6-7853-acc1-607d-946c8fba6ea9@idea> References: <20230204203126.782976-1-ppalka@redhat.com> <3f14f800-4b00-9215-c249-1c7f19d43560@redhat.com> <9b958e6f-6f8b-9183-5277-39f83871dd9d@idea> <0e0bc838-466e-20ea-4523-a075be14ef76@redhat.com> <03f75252-861b-528e-df42-6a88adddb388@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="8323329-1075228681-1675609057=:55455" X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00,BODY_8BITS,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1075228681-1675609057=:55455 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Sat, 4 Feb 2023, Jason Merrill wrote: > On 2/4/23 20:41, Jason Merrill wrote: > > On 2/4/23 20:08, Patrick Palka wrote: > > > On Sat, 4 Feb 2023, Jason Merrill wrote: > > > > > > > On 2/4/23 15:31, Patrick Palka wrote: > > > > > After r13-5684-g59e0376f607805 the (pruned) callee of a non-dependent > > > > > CALL_EXPR is a bare FUNCTION_DECL rather than ADDR_EXPR of > > > > > FUNCTION_DECL. > > > > > This innocent change revealed that cp_tree_equal doesn't first check > > > > > dependentness of a CALL_EXPR before treating the callee as a dependent > > > > > name, which manifests as us incorrectly accepting the first two > > > > > testcases below and rejecting the third: > > > > > > > > > >    * In the first testcase, cp_tree_equal incorrectly returns true for > > > > >      the two non-dependent CALL_EXPRs f(0) and f(0) (whose > > > > > CALL_EXPR_FN > > > > >      are different FUNCTION_DECLs) and so we treat #2 as a > > > > > redeclaration > > > > >      of #1. > > > > > > > > > >    * Same issue in the second testcase, for f() and f(). > > > > > > > > > >    * In the third testcase, cp_tree_equal incorrectly returns true for > > > > >      f() and f() which causes us to conflate the > > > > > two > > > > >      dependent specializations A()(U()))> and > > > > >      A()(U()))>, leading to a bogus error. > > > > > > > > > > This patch fixes this by making called_fns_equal treat two callees as > > > > > dependent names only if the CALL_EXPRs in question are dependent. > > > > > > > > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK > > > > > for > > > > > trunk/12?  Patch generated with -w to ignore noisy whitespace changes. > > > > > > > > > >     PR c++/107461 > > > > > > > > > > gcc/cp/ChangeLog: > > > > > > > > > >     * pt.cc (iterative_hash_template_arg) : Treat > > > > >     the callee as a dependent name only if the CALL_EXPR is > > > > >     dependent. > > > > >     * tree.cc (called_fns_equal): Take two CALL_EXPRs instead of > > > > >     CALL_EXPR_FNs thereof.  As above. > > > > >     (cp_tree_equal) : Adjust call to called_fns_equal. > > > > > > > > > > gcc/testsuite/ChangeLog: > > > > > > > > > >     * g++.dg/cpp0x/overload5.C: New test. > > > > >     * g++.dg/cpp0x/overload5a.C: New test. > > > > >     * g++.dg/cpp0x/overload6.C: New test. > > > > > --- > > > > >    gcc/cp/pt.cc                            |  1 + > > > > >    gcc/cp/tree.cc                          | 33 > > > > > ++++++++++++++----------- > > > > >    gcc/testsuite/g++.dg/cpp0x/overload5.C  | 12 +++++++++ > > > > >    gcc/testsuite/g++.dg/cpp0x/overload5a.C | 10 ++++++++ > > > > >    gcc/testsuite/g++.dg/cpp0x/overload6.C  | 16 ++++++++++++ > > > > >    5 files changed, 58 insertions(+), 14 deletions(-) > > > > >    create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload5.C > > > > >    create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload5a.C > > > > >    create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload6.C > > > > > > > > > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > > > > > index 255332dc0c1..c9360240cd2 100644 > > > > > --- a/gcc/cp/pt.cc > > > > > +++ b/gcc/cp/pt.cc > > > > > @@ -1841,6 +1841,7 @@ iterative_hash_template_arg (tree arg, hashval_t > > > > > val) > > > > >        case CALL_EXPR: > > > > >          { > > > > >        tree fn = CALL_EXPR_FN (arg); > > > > > +    if (TREE_TYPE (arg) == NULL_TREE) > > > > > > > > How about changing dependent_name to take the CALL_EXPR rather than the > > > > CALL_EXPR_FN?  That would mean some changes to write_expression to move > > > > the > > > > dependent_name handling into the CALL_EXPR handling, but that doesn't > > > > seem > > > > like a bad thing.  Other callers seem like a trivial change. > > > > > > Indeed changing dependent_name seems best, but I'm worried about such a > > > refactoring to write_expression causing unintended mangling changes at > > > this stage.  Because it seems the CALL_EXPR case of write_expression > > > isn't the user of the dependent_name branch of write_expression, at > > > least according to the following patch which causes us to ICE on > > > mangle{37,57,58,76}.C: > > > > Yeah, I tried the same thing.  Maybe for GCC 13 better to add a new function > > rather than change the current one. Sounds good, like so? Only regtested so far. Full bootstrap and regtest running on x86_64-pc-linux-gnu. -- >8 -- Subject: [PATCH] c++: equivalence of non-dependent calls [PR107461] After r13-5684-g59e0376f607805 the (pruned) callee of a non-dependent CALL_EXPR is a bare FUNCTION_DECL rather than ADDR_EXPR of FUNCTION_DECL. This innocent change revealed that cp_tree_equal doesn't first check dependentness of a CALL_EXPR before treating a FUNCTION_DECL callee as a dependent name, which manifests as us incorrectly accepting the first two testcases below and rejecting the third: * In the first testcase, cp_tree_equal incorrectly returns true for the two non-dependent CALL_EXPRs f(0) and f(0) (whose CALL_EXPR_FN are different FUNCTION_DECLs) and so we treat #2 as a redeclaration of #1. * Same issue in the second testcase, for f() and f(). * In the third testcase, cp_tree_equal incorrectly returns true for f() and f() which causes us to conflate the two dependent specializations A()(U()))> and A()(U()))>, leading to a bogus error. This patch fixes this by making called_fns_equal treat two callees as dependent names only if the overall CALL_EXPRs are dependent, via a new convenience function call_expr_dependent_name that is like dependent_name but also checks dependence of the overall CALL_EXPR. Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for trunk/12? Patch generated with -w to ignore noisy whitespace changes. PR c++/107461 gcc/cp/ChangeLog: * cp-tree.h (call_expr_dependent_name): Declare. * pt.cc (iterative_hash_template_arg) : Use call_expr_dependent_name instead of dependent_name. * tree.cc (call_expr_dependent_name): Define. (called_fns_equal): Adjust to take two CALL_EXPRs instead of CALL_EXPR_FNs thereof. Use call_expr_dependent_name instead of dependent_name. (cp_tree_equal) : Adjust call to called_fns_equal. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/overload5.C: New test. * g++.dg/cpp0x/overload5a.C: New test. * g++.dg/cpp0x/overload6.C: New test. --- gcc/cp/cp-tree.h | 1 + gcc/cp/pt.cc | 2 +- gcc/cp/tree.cc | 24 +++++++++++++++++++----- gcc/testsuite/g++.dg/cpp0x/overload5.C | 12 ++++++++++++ gcc/testsuite/g++.dg/cpp0x/overload5a.C | 10 ++++++++++ gcc/testsuite/g++.dg/cpp0x/overload6.C | 16 ++++++++++++++++ 6 files changed, 59 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload5.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload5a.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/overload6.C diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 00b2bffc85c..ef601182d4b 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7902,6 +7902,7 @@ extern tree lookup_maybe_add (tree fns, tree lookup, extern int is_overloaded_fn (tree) ATTRIBUTE_PURE; extern bool really_overloaded_fn (tree) ATTRIBUTE_PURE; extern tree dependent_name (tree); +extern tree call_expr_dependent_name (tree); extern tree maybe_get_fns (tree) ATTRIBUTE_PURE; extern tree get_fns (tree) ATTRIBUTE_PURE; extern tree get_first_fn (tree) ATTRIBUTE_PURE; diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 255332dc0c1..9f3fc1fa089 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -1841,7 +1841,7 @@ iterative_hash_template_arg (tree arg, hashval_t val) case CALL_EXPR: { tree fn = CALL_EXPR_FN (arg); - if (tree name = dependent_name (fn)) + if (tree name = call_expr_dependent_name (arg)) { if (TREE_CODE (fn) == TEMPLATE_ID_EXPR) val = iterative_hash_template_arg (TREE_OPERAND (fn, 1), val); diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc index c1da868732b..880bd4f9bcf 100644 --- a/gcc/cp/tree.cc +++ b/gcc/cp/tree.cc @@ -2608,6 +2608,18 @@ dependent_name (tree x) return NULL_TREE; } +/* Like dependent_name, but takes the overall CALL_EXPR and checks its + dependence. */ + +tree +call_expr_dependent_name (tree x) +{ + if (TREE_TYPE (x) != NULL_TREE) + /* X isn't dependent, so its callee isn't a dependent name. */ + return NULL_TREE; + return dependent_name (CALL_EXPR_FN (x)); +} + /* Returns true iff X is an expression for an overloaded function whose type cannot be known without performing overload resolution. */ @@ -3870,16 +3882,18 @@ decl_internal_context_p (const_tree decl) return !TREE_PUBLIC (decl); } -/* Subroutine of cp_tree_equal: t1 and t2 are the CALL_EXPR_FNs of two - CALL_EXPRS. Return whether they are equivalent. */ +/* Subroutine of cp_tree_equal: t1 and t2 are two CALL_EXPRs. + Return whether their CALL_EXPR_FNs are equivalent. */ static bool called_fns_equal (tree t1, tree t2) { /* Core 1321: dependent names are equivalent even if the overload sets are different. But do compare explicit template arguments. */ - tree name1 = dependent_name (t1); - tree name2 = dependent_name (t2); + tree name1 = call_expr_dependent_name (t1); + tree name2 = call_expr_dependent_name (t2); + t1 = CALL_EXPR_FN (t1); + t2 = CALL_EXPR_FN (t2); if (name1 || name2) { tree targs1 = NULL_TREE, targs2 = NULL_TREE; @@ -4037,7 +4051,7 @@ cp_tree_equal (tree t1, tree t2) if (KOENIG_LOOKUP_P (t1) != KOENIG_LOOKUP_P (t2)) return false; - if (!called_fns_equal (CALL_EXPR_FN (t1), CALL_EXPR_FN (t2))) + if (!called_fns_equal (t1, t2)) return false; call_expr_arg_iterator iter1, iter2; diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5.C b/gcc/testsuite/g++.dg/cpp0x/overload5.C new file mode 100644 index 00000000000..e05b1594f51 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload5.C @@ -0,0 +1,12 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +int f(...); +template decltype(T() + f(0)) g(); // #1 + +char f(int); +template decltype(T() + f(0)) g(); // #2, distinct from #1 + +int main() { + g(); // { dg-error "ambiguous" } +} diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5a.C b/gcc/testsuite/g++.dg/cpp0x/overload5a.C new file mode 100644 index 00000000000..037114f199c --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload5a.C @@ -0,0 +1,10 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +template T f(); +template decltype(T() + f()) g(); // #1 +template decltype(T() + f()) g(); // #2, distinct from #1 + +int main() { + g(); // { dg-error "ambiguous" } +} diff --git a/gcc/testsuite/g++.dg/cpp0x/overload6.C b/gcc/testsuite/g++.dg/cpp0x/overload6.C new file mode 100644 index 00000000000..1fbee0501de --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload6.C @@ -0,0 +1,16 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +template T f(); + +template struct A { }; + +template struct B { + template()(U()))>> + static void g(U); +}; + +int main() { + B b; + B::g(0); // { dg-bogus "no match" } +} -- 2.39.1.409.ga6a323b31e > > mangle76 seems like a bug where we're producing (and testing for) the wrong > mangling -- mangling (*this). that doesn't exist in the source. clang gets it > right. > > mangle5{7,8} has the right mangling, we're just using dependent_name to mangle > function names that aren't dependent names (because they're template arguments > in both cases, and qualified in the latter). > > > > diff --git a/gcc/cp/mangle.cc b/gcc/cp/mangle.cc > > > index f2cda3be2cf..700857f8f3c 100644 > > > --- a/gcc/cp/mangle.cc > > > +++ b/gcc/cp/mangle.cc > > > @@ -3450,6 +3450,7 @@ write_expression (tree expr) > > >       } > > >     else if (dependent_name (expr)) > > >       { > > > +      gcc_unreachable (); > > >         tree name = dependent_name (expr); > > >         if (IDENTIFIER_ANY_OP_P (name)) > > >       { > > > @@ -3554,7 +3555,19 @@ write_expression (tree expr) > > >           && type_dependent_expression_p_push (expr)) > > >             fn = OVL_NAME (fn); > > > -        write_expression (fn); > > > +        if (tree name = dependent_name (fn)) > > > +          { > > > +        if (IDENTIFIER_ANY_OP_P (name)) > > > +          { > > > +            if (abi_version_at_least (16)) > > > +              write_string ("on"); > > > +            if (abi_warn_or_compat_version_crosses (16)) > > > +              G.need_abi_warning = 1; > > > +          } > > > +        write_unqualified_id (name); > > > +          } > > > +        else > > > +          write_expression (fn); > > >         } > > >         for (i = 0; i < call_expr_nargs (expr); ++i) > > > > > > And since the CALL_EXPR case of write_expression looks through an > > > ADDR_EXPR callee before recursing, IIUC the refactoring would need to > > > make dependent_name look through an ADDR_EXPR callee as well, which > > > seems like a desirable/correct change but I'm worried that might have > > > unintended consequences as well. > > > > > > > > > > > >          if (tree name = dependent_name (fn)) > > > > >            { > > > > >              if (TREE_CODE (fn) == TEMPLATE_ID_EXPR) > > > > > diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc > > > > > index c1da868732b..3a57e71b76e 100644 > > > > > --- a/gcc/cp/tree.cc > > > > > +++ b/gcc/cp/tree.cc > > > > > @@ -3870,16 +3870,21 @@ decl_internal_context_p (const_tree decl) > > > > >      return !TREE_PUBLIC (decl); > > > > >    } > > > > >    -/* Subroutine of cp_tree_equal: t1 and t2 are the CALL_EXPR_FNs of > > > > > two > > > > > -   CALL_EXPRS.  Return whether they are equivalent.  */ > > > > > +/* Subroutine of cp_tree_equal: t1 and t2 are two CALL_EXPRs. > > > > > +   Return whether their CALL_EXPR_FNs are equivalent.  */ > > > > >      static bool > > > > >    called_fns_equal (tree t1, tree t2) > > > > > +{ > > > > > +  tree fn1 = CALL_EXPR_FN (t1); > > > > > +  tree fn2 = CALL_EXPR_FN (t2); > > > > > +  if (TREE_TYPE (t1) == NULL_TREE > > > > > +      && TREE_TYPE (t2) == NULL_TREE) > > > > >        { > > > > >          /* Core 1321: dependent names are equivalent even if the > > > > > overload > > > > > sets > > > > >         are different.  But do compare explicit template arguments.  > > > > > */ > > > > > -  tree name1 = dependent_name (t1); > > > > > -  tree name2 = dependent_name (t2); > > > > > +      tree name1 = dependent_name (fn1); > > > > > +      tree name2 = dependent_name (fn2); > > > > >          if (name1 || name2) > > > > >        { > > > > >          tree targs1 = NULL_TREE, targs2 = NULL_TREE; > > > > > @@ -3891,19 +3896,19 @@ called_fns_equal (tree t1, tree t2) > > > > >             of whether the function was named with a qualified- or > > > > > unqualified-id. > > > > >             Until that's fixed, check that we aren't looking at > > > > > overload sets > > > > > from > > > > >             different scopes.  */ > > > > > -      if (is_overloaded_fn (t1) && is_overloaded_fn (t2) > > > > > -      && (DECL_CONTEXT (get_first_fn (t1)) > > > > > -          != DECL_CONTEXT (get_first_fn (t2)))) > > > > > +      if (is_overloaded_fn (fn1) && is_overloaded_fn (fn2) > > > > > +          && (DECL_CONTEXT (get_first_fn (fn1)) > > > > > +          != DECL_CONTEXT (get_first_fn (fn2)))) > > > > >            return false; > > > > >    -      if (TREE_CODE (t1) == TEMPLATE_ID_EXPR) > > > > > -    targs1 = TREE_OPERAND (t1, 1); > > > > > -      if (TREE_CODE (t2) == TEMPLATE_ID_EXPR) > > > > > -    targs2 = TREE_OPERAND (t2, 1); > > > > > +      if (TREE_CODE (fn1) == TEMPLATE_ID_EXPR) > > > > > +        targs1 = TREE_OPERAND (fn1, 1); > > > > > +      if (TREE_CODE (fn2) == TEMPLATE_ID_EXPR) > > > > > +        targs2 = TREE_OPERAND (fn2, 1); > > > > >          return cp_tree_equal (targs1, targs2); > > > > >        } > > > > > -  else > > > > > -    return cp_tree_equal (t1, t2); > > > > > +    } > > > > > +  return cp_tree_equal (fn1, fn2); > > > > >    } > > > > >      bool comparing_override_contracts; > > > > > @@ -4037,7 +4042,7 @@ cp_tree_equal (tree t1, tree t2) > > > > >        if (KOENIG_LOOKUP_P (t1) != KOENIG_LOOKUP_P (t2)) > > > > >          return false; > > > > >    -    if (!called_fns_equal (CALL_EXPR_FN (t1), CALL_EXPR_FN (t2))) > > > > > +    if (!called_fns_equal (t1, t2)) > > > > >          return false; > > > > >          call_expr_arg_iterator iter1, iter2; > > > > > diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5.C > > > > > b/gcc/testsuite/g++.dg/cpp0x/overload5.C > > > > > new file mode 100644 > > > > > index 00000000000..e05b1594f51 > > > > > --- /dev/null > > > > > +++ b/gcc/testsuite/g++.dg/cpp0x/overload5.C > > > > > @@ -0,0 +1,12 @@ > > > > > +// PR c++/107461 > > > > > +// { dg-do compile { target c++11 } } > > > > > + > > > > > +int f(...); > > > > > +template decltype(T() + f(0)) g(); // #1 > > > > > + > > > > > +char f(int); > > > > > +template decltype(T() + f(0)) g(); // #2, distinct from #1 > > > > > + > > > > > +int main() { > > > > > +  g(); // { dg-error "ambiguous" } > > > > > +} > > > > > diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5a.C > > > > > b/gcc/testsuite/g++.dg/cpp0x/overload5a.C > > > > > new file mode 100644 > > > > > index 00000000000..037114f199c > > > > > --- /dev/null > > > > > +++ b/gcc/testsuite/g++.dg/cpp0x/overload5a.C > > > > > @@ -0,0 +1,10 @@ > > > > > +// PR c++/107461 > > > > > +// { dg-do compile { target c++11 } } > > > > > + > > > > > +template T f(); > > > > > +template decltype(T() + f()) g(); // #1 > > > > > +template decltype(T() + f()) g(); // #2, distinct from > > > > > #1 > > > > > + > > > > > +int main() { > > > > > +  g(); // { dg-error "ambiguous" } > > > > > +} > > > > > diff --git a/gcc/testsuite/g++.dg/cpp0x/overload6.C > > > > > b/gcc/testsuite/g++.dg/cpp0x/overload6.C > > > > > new file mode 100644 > > > > > index 00000000000..1fbee0501de > > > > > --- /dev/null > > > > > +++ b/gcc/testsuite/g++.dg/cpp0x/overload6.C > > > > > @@ -0,0 +1,16 @@ > > > > > +// PR c++/107461 > > > > > +// { dg-do compile { target c++11 } } > > > > > + > > > > > +template T f(); > > > > > + > > > > > +template struct A { }; > > > > > + > > > > > +template struct B { > > > > > +  template()(U()))>> > > > > > +  static void g(U); > > > > > +}; > > > > > + > > > > > +int main() { > > > > > +  B b; > > > > > +  B::g(0); // { dg-bogus "no match" } > > > > > +} > > > > > > > > > > > > > > > --8323329-1075228681-1675609057=:55455--