| Message ID | 20240311232758.458729-1-polacek@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: ICE with temporary of class type in array DMI [PR109966] | expand |
On 3/11/24 19:27, Marek Polacek wrote: > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/13? > > -- >8 -- > This ICE started with the fairly complicated r13-765. We crash in > gimplify_var_or_parm_decl because a stray VAR_DECL leaked there. > The problem is ultimately that potential_prvalue_result_of wasn't > correctly handling arrays and replace_placeholders_for_class_temp_r > replaced a PLACEHOLDER_EXPR in a TARGET_EXPR which is used in the > context of copy elision. If I have > > M m[2] = { M{""}, M{""} }; > > then we don't invoke the M(const M&) copy-ctor. I think the fix is > to detect such a case in potential_prvalue_result_of. > > PR c++/109966 > > gcc/cp/ChangeLog: > > * typeck2.cc (potential_prvalue_result_of): Add walk_subtrees > parameter. Handle initializing an array from a > brace-enclosed-initializer. > (replace_placeholders_for_class_temp_r): Pass walk_subtrees down to > potential_prvalue_result_of. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp1y/nsdmi-aggr20.C: New test. > * g++.dg/cpp1y/nsdmi-aggr21.C: New test. > --- > gcc/cp/typeck2.cc | 27 ++++++++--- > gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C | 17 +++++++ > gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C | 59 +++++++++++++++++++++++ > 3 files changed, 96 insertions(+), 7 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C > create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C > > diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc > index 31198b2f9f5..8b99ce78e9a 100644 > --- a/gcc/cp/typeck2.cc > +++ b/gcc/cp/typeck2.cc > @@ -1406,46 +1406,59 @@ digest_init_flags (tree type, tree init, int flags, tsubst_flags_t complain) > A a = (A{}); // initializer > A a = (1, A{}); // initializer > A a = true ? A{} : A{}; // initializer > + A arr[1] = { A{} }; // initializer > auto x = A{}.x; // temporary materialization > auto x = foo(A{}); // temporary materialization > > FULL_EXPR is the whole expression, SUBOB is its TARGET_EXPR subobject. */ > > static bool > -potential_prvalue_result_of (tree subob, tree full_expr) > +potential_prvalue_result_of (tree subob, tree full_expr, int *walk_subtrees) > { > +#define RECUR(t) potential_prvalue_result_of (subob, t, walk_subtrees) > if (subob == full_expr) > return true; > else if (TREE_CODE (full_expr) == TARGET_EXPR) > { > tree init = TARGET_EXPR_INITIAL (full_expr); > if (TREE_CODE (init) == COND_EXPR) > - return (potential_prvalue_result_of (subob, TREE_OPERAND (init, 1)) > - || potential_prvalue_result_of (subob, TREE_OPERAND (init, 2))); > + return (RECUR (TREE_OPERAND (init, 1)) > + || RECUR (TREE_OPERAND (init, 2))); > else if (TREE_CODE (init) == COMPOUND_EXPR) > - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 1)); > + return RECUR (TREE_OPERAND (init, 1)); > /* ??? I don't know if this can be hit. */ > else if (TREE_CODE (init) == PAREN_EXPR) > { > gcc_checking_assert (false); > - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 0)); > + return RECUR (TREE_OPERAND (init, 0)); > } > } > + /* The array case listed above. */ > + else if (TREE_CODE (full_expr) == CONSTRUCTOR > + && TREE_CODE (TREE_TYPE (full_expr)) == ARRAY_TYPE) > + for (constructor_elt &e: CONSTRUCTOR_ELTS (full_expr)) > + if (e.value == subob) > + { > + *walk_subtrees = 0; Why clear walk_subtrees? Won't that mean we fail to replace any placeholders nested within an array element initializer? Jason
diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc index 31198b2f9f5..8b99ce78e9a 100644 --- a/gcc/cp/typeck2.cc +++ b/gcc/cp/typeck2.cc @@ -1406,46 +1406,59 @@ digest_init_flags (tree type, tree init, int flags, tsubst_flags_t complain) A a = (A{}); // initializer A a = (1, A{}); // initializer A a = true ? A{} : A{}; // initializer + A arr[1] = { A{} }; // initializer auto x = A{}.x; // temporary materialization auto x = foo(A{}); // temporary materialization FULL_EXPR is the whole expression, SUBOB is its TARGET_EXPR subobject. */ static bool -potential_prvalue_result_of (tree subob, tree full_expr) +potential_prvalue_result_of (tree subob, tree full_expr, int *walk_subtrees) { +#define RECUR(t) potential_prvalue_result_of (subob, t, walk_subtrees) if (subob == full_expr) return true; else if (TREE_CODE (full_expr) == TARGET_EXPR) { tree init = TARGET_EXPR_INITIAL (full_expr); if (TREE_CODE (init) == COND_EXPR) - return (potential_prvalue_result_of (subob, TREE_OPERAND (init, 1)) - || potential_prvalue_result_of (subob, TREE_OPERAND (init, 2))); + return (RECUR (TREE_OPERAND (init, 1)) + || RECUR (TREE_OPERAND (init, 2))); else if (TREE_CODE (init) == COMPOUND_EXPR) - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 1)); + return RECUR (TREE_OPERAND (init, 1)); /* ??? I don't know if this can be hit. */ else if (TREE_CODE (init) == PAREN_EXPR) { gcc_checking_assert (false); - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 0)); + return RECUR (TREE_OPERAND (init, 0)); } } + /* The array case listed above. */ + else if (TREE_CODE (full_expr) == CONSTRUCTOR + && TREE_CODE (TREE_TYPE (full_expr)) == ARRAY_TYPE) + for (constructor_elt &e: CONSTRUCTOR_ELTS (full_expr)) + if (e.value == subob) + { + *walk_subtrees = 0; + return true; + } + return false; +#undef RECUR } /* Callback to replace PLACEHOLDER_EXPRs in a TARGET_EXPR (which isn't used in the context of guaranteed copy elision). */ static tree -replace_placeholders_for_class_temp_r (tree *tp, int *, void *data) +replace_placeholders_for_class_temp_r (tree *tp, int *walk_subtrees, void *data) { tree t = *tp; tree full_expr = *static_cast<tree *>(data); /* We're looking for a TARGET_EXPR nested in the whole expression. */ if (TREE_CODE (t) == TARGET_EXPR - && !potential_prvalue_result_of (t, full_expr)) + && !potential_prvalue_result_of (t, full_expr, walk_subtrees)) { tree init = TARGET_EXPR_INITIAL (t); while (TREE_CODE (init) == COMPOUND_EXPR) diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C new file mode 100644 index 00000000000..4796d861e83 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C @@ -0,0 +1,17 @@ +// PR c++/109966 +// { dg-do compile { target c++14 } } + +#define SA(X) static_assert ((X),#X) + +struct A { + int a; + int b = a; +}; + +struct B { + int x = 0; + int y[1]{A{x}.b}; +}; + +constexpr B b = { }; +SA(b.y[0] == 0); diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C new file mode 100644 index 00000000000..efec45bc1a8 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C @@ -0,0 +1,59 @@ +// PR c++/109966 +// { dg-do compile { target c++14 } } + +struct k { + k(const char *); +}; +struct M { + k name; + int j = 42; + int i = j; +}; + +M m = M{""}; + +struct S { + M arr1[1]{M{""}}; + M a1[1] = { (M{""}) }; + M a2[1] = { (true, M{""}) }; + M a3[1] = { true ? M{""} : M{""} }; + M arr2[2]{M{""}, M{""}}; + M arr3[3]{M{""}, M{""}, M{""}}; + + M arr1e[1] = {M{""}}; + M arr2e[2] = {M{""}, M{""}}; + M arr3e[3] = {M{""}, M{""}, M{""}}; + + M arr1l[1] = { m }; + M arr2l[2] = { m, m }; + M arr3l[3] = { m, m, m }; + + M m1 = M{""}; + M m2 = m; + M m3{M{""}}; + M m4 = {M{""}}; +} o; + +struct N { + N(M); +}; + +struct Z { + N arr1[1]{ M{""} }; + N arr2[2]{ M{""}, M{""} }; + N arr1e[1] = { M{""} }; + N arr2e[2] = { M{""}, M{""} }; +} z; + +struct Y { + k name; + int j = 42; + int i = j; + operator M(); +}; + +struct W { + M arr1[1]{ Y{""} }; + M arr2[2]{ Y{""}, Y{""} }; + M arr3[3]{ Y{""}, Y{""}, Y{""} }; +} w;
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/13? -- >8 -- This ICE started with the fairly complicated r13-765. We crash in gimplify_var_or_parm_decl because a stray VAR_DECL leaked there. The problem is ultimately that potential_prvalue_result_of wasn't correctly handling arrays and replace_placeholders_for_class_temp_r replaced a PLACEHOLDER_EXPR in a TARGET_EXPR which is used in the context of copy elision. If I have M m[2] = { M{""}, M{""} }; then we don't invoke the M(const M&) copy-ctor. I think the fix is to detect such a case in potential_prvalue_result_of. PR c++/109966 gcc/cp/ChangeLog: * typeck2.cc (potential_prvalue_result_of): Add walk_subtrees parameter. Handle initializing an array from a brace-enclosed-initializer. (replace_placeholders_for_class_temp_r): Pass walk_subtrees down to potential_prvalue_result_of. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/nsdmi-aggr20.C: New test. * g++.dg/cpp1y/nsdmi-aggr21.C: New test. --- gcc/cp/typeck2.cc | 27 ++++++++--- gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C | 17 +++++++ gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C | 59 +++++++++++++++++++++++ 3 files changed, 96 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C base-commit: 0c179654c3170749f3fb3232f2442fcbc99bffbb