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| author | Marek Polacek <polacek@redhat.com> | 2020-02-19 16:36:38 -0500 |
|---|---|---|
| committer | Marek Polacek <polacek@redhat.com> | 2020-02-19 19:14:29 -0500 |
| commit | 8f9dd1b0bdd935592ba151e9d843fddf6193afbc (patch) | |
| tree | e19b0e3022901799a7fae3326655494fc1ad49a6 | |
| parent | ccf86d54cb02ed24bc4568bd9fffdcdbf0bf68a8 (diff) | |
| download | gcc-8f9dd1b0bdd935592ba151e9d843fddf6193afbc.zip gcc-8f9dd1b0bdd935592ba151e9d843fddf6193afbc.tar.gz gcc-8f9dd1b0bdd935592ba151e9d843fddf6193afbc.tar.bz2 | |
c++: Fix wrong-code with non-constexpr constructor [PR93169]
In order to detect modifying constant objects in constexpr evaluation,
which is UB, in r10-2655 I added code that sets TREE_READONLY on
CONSTRUCTORs of const-qualified objects after they have been fully
constructed. But I never made sure that what we're setting the flag
on actually is a CONSTRUCTOR. Consequently, as this test case shows,
we could set TREE_READONLY on a VAR_DECL that in fact wasn't constant,
causing problems later. Fixed by setting the flag on CONSTRUCTORs
only, and only when the evaluation produced something constant.
2020-02-19 Marek Polacek <polacek@redhat.com>
PR c++/93169 - wrong-code with a non-constexpr constructor.
* constexpr.c (cxx_eval_call_expression): Only set TREE_READONLY
on constant CONSTRUCTORs.
* g++.dg/cpp0x/constexpr-93169.C: New test.
| -rw-r--r-- | gcc/cp/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/cp/constexpr.c | 3 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp0x/constexpr-93169.C | 21 |
4 files changed, 34 insertions, 1 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index f6b5517..e1ac5b0 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,9 @@ +2020-02-19 Marek Polacek <polacek@redhat.com> + + PR c++/93169 - wrong-code with a non-constexpr constructor. + * constexpr.c (cxx_eval_call_expression): Only set TREE_READONLY + on constant CONSTRUCTORs. + 2020-02-15 Marek Polacek <polacek@redhat.com> PR c++/93710 - poor diagnostic for array initializer. diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index bf7a264..128f760 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -2474,7 +2474,8 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t, /*lval*/false, non_constant_p, overflow_p); - TREE_READONLY (e) = true; + if (TREE_CODE (e) == CONSTRUCTOR && !*non_constant_p) + TREE_READONLY (e) = true; } /* Forget the saved values of the callee's SAVE_EXPRs and diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 049c343..a54505e 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-02-19 Marek Polacek <polacek@redhat.com> + + PR c++/93169 - wrong-code with a non-constexpr constructor. + * g++.dg/cpp0x/constexpr-93169.C: New test. + 2020-02-19 Martin Sebor <msebor@redhat.com> PR tree-optimization/92128 diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-93169.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-93169.C new file mode 100644 index 0000000..79fd352 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-93169.C @@ -0,0 +1,21 @@ +// PR c++/93169 - Wrong-code with a non-constexpr constructor. +// { dg-do run { target c++11 } } +// { dg-options "-O2" } + +template <typename T> class B { + struct C { + T h; + constexpr C() {} + ~C() {} + } c; +}; +struct S { + int g; + S() { g = 2; } +}; + +int +main() +{ + static const B<S> f; +} |