Re: [PATCH] c++: unpropagated CONSTRUCTOR_MUTABLE_POISON [PR110463]

[Jason Merrill via Gcc-patches]

On 6/29/23 11:36, Marek Polacek wrote:

On Thu, Jun 29, 2023 at 11:22:55AM -0400, Patrick Palka via Gcc-patches wrote:

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/13?

-- >8 --

cp_fold is neglecting to propagate CONSTRUCTOR_MUTABLE_POISON when folding
a CONSTRUCTOR initializer, which for the below testcase causes us to fail
to reject a mutable member access of a constexpr variable during constexpr
evaluation.


LGTM.


Agreed, OK.


PR c++/110463

gcc/cp/ChangeLog:

* cp-gimplify.cc (cp_fold) : Propagate
CONSTRUCTOR_MUTABLE_POISON.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/constexpr-mutable6.C: New test.
---
  gcc/cp/cp-gimplify.cc  |  2 ++
  .../g++.dg/cpp0x/constexpr-mutable6.C  | 18 ++
  2 files changed, 20 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 853b1e44236..f5734197774 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -3079,6 +3079,8 @@ cp_fold (tree x, fold_flags_t flags)
x = build_constructor (TREE_TYPE (x), nelts);
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (x)
  = CONSTRUCTOR_PLACEHOLDER_BOUNDARY (org_x);
+   CONSTRUCTOR_MUTABLE_POISON (x)
+ = CONSTRUCTOR_MUTABLE_POISON (org_x);
  }
if (VECTOR_TYPE_P (TREE_TYPE (x)))
  x = fold (x);
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C 
b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
new file mode 100644
index 000..2c946e388ab
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
@@ -0,0 +1,18 @@
+// PR c++/110463
+// { dg-do compile { target c++11 } }
+
+struct U {
+  mutable int x = 1;
+};
+
+struct V {
+  mutable int y = 1+1;
+};
+
+int main() {
+  constexpr U u = {};
+  constexpr int x = u.x; // { dg-error "mutable" }
+
+  constexpr V v = {};
+  constexpr int y = v.y; // { dg-error "mutable" }
+}
--
2.41.0.199.ga9e066fa63



Marek

Re: [PATCH] c++: unpropagated CONSTRUCTOR_MUTABLE_POISON [PR110463]

[Marek Polacek via Gcc-patches]

On Thu, Jun 29, 2023 at 11:22:55AM -0400, Patrick Palka via Gcc-patches wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk/13?
> 
> -- >8 --
> 
> cp_fold is neglecting to propagate CONSTRUCTOR_MUTABLE_POISON when folding
> a CONSTRUCTOR initializer, which for the below testcase causes us to fail
> to reject a mutable member access of a constexpr variable during constexpr
> evaluation.

LGTM.
 
>   PR c++/110463
> 
> gcc/cp/ChangeLog:
> 
>   * cp-gimplify.cc (cp_fold) : Propagate
>   CONSTRUCTOR_MUTABLE_POISON.
> 
> gcc/testsuite/ChangeLog:
> 
>   * g++.dg/cpp0x/constexpr-mutable6.C: New test.
> ---
>  gcc/cp/cp-gimplify.cc  |  2 ++
>  .../g++.dg/cpp0x/constexpr-mutable6.C  | 18 ++
>  2 files changed, 20 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
> 
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index 853b1e44236..f5734197774 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -3079,6 +3079,8 @@ cp_fold (tree x, fold_flags_t flags)
>   x = build_constructor (TREE_TYPE (x), nelts);
>   CONSTRUCTOR_PLACEHOLDER_BOUNDARY (x)
> = CONSTRUCTOR_PLACEHOLDER_BOUNDARY (org_x);
> + CONSTRUCTOR_MUTABLE_POISON (x)
> +   = CONSTRUCTOR_MUTABLE_POISON (org_x);
> }
>   if (VECTOR_TYPE_P (TREE_TYPE (x)))
> x = fold (x);
> diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C 
> b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
> new file mode 100644
> index 000..2c946e388ab
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
> @@ -0,0 +1,18 @@
> +// PR c++/110463
> +// { dg-do compile { target c++11 } }
> +
> +struct U {
> +  mutable int x = 1;
> +};
> +
> +struct V {
> +  mutable int y = 1+1;
> +};
> +
> +int main() {
> +  constexpr U u = {};
> +  constexpr int x = u.x; // { dg-error "mutable" }
> +
> +  constexpr V v = {};
> +  constexpr int y = v.y; // { dg-error "mutable" }
> +}
> -- 
> 2.41.0.199.ga9e066fa63
> 

Marek

[PATCH] c++: unpropagated CONSTRUCTOR_MUTABLE_POISON [PR110463]

[Patrick Palka via Gcc-patches]

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/13?

-- >8 --

cp_fold is neglecting to propagate CONSTRUCTOR_MUTABLE_POISON when folding
a CONSTRUCTOR initializer, which for the below testcase causes us to fail
to reject a mutable member access of a constexpr variable during constexpr
evaluation.

PR c++/110463

gcc/cp/ChangeLog:

* cp-gimplify.cc (cp_fold) : Propagate
CONSTRUCTOR_MUTABLE_POISON.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/constexpr-mutable6.C: New test.
---
 gcc/cp/cp-gimplify.cc  |  2 ++
 .../g++.dg/cpp0x/constexpr-mutable6.C  | 18 ++
 2 files changed, 20 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C

diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 853b1e44236..f5734197774 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -3079,6 +3079,8 @@ cp_fold (tree x, fold_flags_t flags)
x = build_constructor (TREE_TYPE (x), nelts);
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (x)
  = CONSTRUCTOR_PLACEHOLDER_BOUNDARY (org_x);
+   CONSTRUCTOR_MUTABLE_POISON (x)
+ = CONSTRUCTOR_MUTABLE_POISON (org_x);
  }
if (VECTOR_TYPE_P (TREE_TYPE (x)))
  x = fold (x);
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C 
b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
new file mode 100644
index 000..2c946e388ab
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-mutable6.C
@@ -0,0 +1,18 @@
+// PR c++/110463
+// { dg-do compile { target c++11 } }
+
+struct U {
+  mutable int x = 1;
+};
+
+struct V {
+  mutable int y = 1+1;
+};
+
+int main() {
+  constexpr U u = {};
+  constexpr int x = u.x; // { dg-error "mutable" }
+
+  constexpr V v = {};
+  constexpr int y = v.y; // { dg-error "mutable" }
+}
-- 
2.41.0.199.ga9e066fa63