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| author | Jason Merrill <jason@redhat.com> | 2017-02-10 13:50:30 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@gcc.gnu.org> | 2017-02-10 13:50:30 -0500 |
| commit | 5c97093ba7feef2235c45233a2a1175c8c168b4c (patch) | |
| tree | ca9ee3b791d659df5e956f947849e73bb4d09560 | |
| parent | f494ac0ebd96a964914b7d9cc7b208a69865f9f1 (diff) | |
| download | gcc-5c97093ba7feef2235c45233a2a1175c8c168b4c.zip gcc-5c97093ba7feef2235c45233a2a1175c8c168b4c.tar.gz gcc-5c97093ba7feef2235c45233a2a1175c8c168b4c.tar.bz2 | |
PR c++/78897 - constexpr union
* constexpr.c (cxx_eval_store_expression): A store to a union member
erases a previous store to another member.
From-SVN: r245341
| -rw-r--r-- | gcc/cp/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/cp/constexpr.c | 5 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1y/constexpr-union1.C | 11 |
3 files changed, 20 insertions, 0 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 68c5d9d..be51428 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,9 @@ 2017-02-10 Jason Merrill <jason@redhat.com> + PR c++/78897 - constexpr union + * constexpr.c (cxx_eval_store_expression): A store to a union member + erases a previous store to another member. + PR c++/71285 - member of fold-expression * semantics.c (finish_unary_fold_expr) (finish_binary_fold_expr): Use null type for fold-expressions. diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index bb45f1e..bfdde9e 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -3466,6 +3466,11 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, tree fields = TYPE_FIELDS (DECL_CONTEXT (index)); unsigned HOST_WIDE_INT idx; + if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp) + && CONSTRUCTOR_ELT (*valp, 0)->index != index) + /* Changing active member. */ + vec_safe_truncate (CONSTRUCTOR_ELTS (*valp), 0); + for (idx = 0; vec_safe_iterate (CONSTRUCTOR_ELTS (*valp), idx, &cep); idx++, fields = DECL_CHAIN (fields)) diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-union1.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-union1.C new file mode 100644 index 0000000..8aed6d9 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-union1.C @@ -0,0 +1,11 @@ +// PR c++/78897 +// { dg-do compile { target c++14 } } + +struct Optional { + constexpr Optional() : _dummy{} { _value = 1; } + union { + int _dummy; + int _value; + }; +}; +Optional opt{}; |