c++: -Wuninitialized when binding a ref to uninit DM [PR113987]
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Commit Message
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
This PR asks that our -Wuninitialized for mem-initializers does
not warn when binding a reference to an uninitialized data member.
We already check !INDIRECT_TYPE_P in find_uninit_fields_r, but
that won't catch binding a parameter of a reference type to an
uninitialized field, as in:
struct S { S (int&); };
struct T {
T() : s(i) {}
S s;
int i;
};
This patch adds a new function to handle this case.
PR c++/113987
gcc/cp/ChangeLog:
* call.cc (conv_binds_to_reference_parm_p): New.
* cp-tree.h (conv_binds_to_reference_parm_p): Declare.
* init.cc (find_uninit_fields_r): Call it.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wuninitialized-15.C: Turn dg-warning into dg-bogus.
* g++.dg/warn/Wuninitialized-34.C: New test.
---
gcc/cp/call.cc | 24 ++++++++++++++
gcc/cp/cp-tree.h | 1 +
gcc/cp/init.cc | 3 +-
gcc/testsuite/g++.dg/warn/Wuninitialized-15.C | 3 +-
gcc/testsuite/g++.dg/warn/Wuninitialized-34.C | 32 +++++++++++++++++++
5 files changed, 60 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
base-commit: ca5f509903315a56b2f306f8644544861a6525cb
Comments
On 2/20/24 19:15, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> -- >8 --
> This PR asks that our -Wuninitialized for mem-initializers does
> not warn when binding a reference to an uninitialized data member.
> We already check !INDIRECT_TYPE_P in find_uninit_fields_r, but
> that won't catch binding a parameter of a reference type to an
> uninitialized field, as in:
>
> struct S { S (int&); };
> struct T {
> T() : s(i) {}
> S s;
> int i;
> };
>
> This patch adds a new function to handle this case.
For type_build_ctor_call types like S, it's weird that we currently
find_uninit_fields before building the initialization. What if we move
the check after the build_aggr_init so we have the actual initializer
instead of just the expression?
> PR c++/113987
>
> gcc/cp/ChangeLog:
>
> * call.cc (conv_binds_to_reference_parm_p): New.
> * cp-tree.h (conv_binds_to_reference_parm_p): Declare.
> * init.cc (find_uninit_fields_r): Call it.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/warn/Wuninitialized-15.C: Turn dg-warning into dg-bogus.
> * g++.dg/warn/Wuninitialized-34.C: New test.
> ---
> gcc/cp/call.cc | 24 ++++++++++++++
> gcc/cp/cp-tree.h | 1 +
> gcc/cp/init.cc | 3 +-
> gcc/testsuite/g++.dg/warn/Wuninitialized-15.C | 3 +-
> gcc/testsuite/g++.dg/warn/Wuninitialized-34.C | 32 +++++++++++++++++++
> 5 files changed, 60 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
>
> diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
> index 1dac1470d3b..c40ef2e3028 100644
> --- a/gcc/cp/call.cc
> +++ b/gcc/cp/call.cc
> @@ -14551,4 +14551,28 @@ maybe_show_nonconverting_candidate (tree to, tree from, tree arg, int flags)
> "function was not considered");
> }
>
> +/* We're converting EXPR to TYPE. If that conversion involves a conversion
> + function and we're binding EXPR to a reference parameter of that function,
> + return true. */
> +
> +bool
> +conv_binds_to_reference_parm_p (tree type, tree expr)
> +{
> + conversion_obstack_sentinel cos;
> + conversion *c = implicit_conversion (type, TREE_TYPE (expr), expr,
> + /*c_cast_p=*/false, LOOKUP_NORMAL,
> + tf_none);
> + if (c && !c->bad_p && c->user_conv_p)
> + for (; c; c = next_conversion (c))
> + if (c->kind == ck_user)
> + for (z_candidate *cand = c->cand; cand; cand = cand->next)
> + if (cand->viable == 1)
> + for (size_t i = 0; i < cand->num_convs; ++i)
> + if (cand->convs[i]->kind == ck_ref_bind
> + && conv_get_original_expr (cand->convs[i]) == expr)
> + return true;
> +
> + return false;
> +}
> +
> #include "gt-cp-call.h"
> diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> index 334c11396c2..ce2d85f1f86 100644
> --- a/gcc/cp/cp-tree.h
> +++ b/gcc/cp/cp-tree.h
> @@ -6845,6 +6845,7 @@ extern void cp_warn_deprecated_use_scopes (tree);
> extern tree get_function_version_dispatcher (tree);
> extern bool any_template_arguments_need_structural_equality_p (tree);
> extern void maybe_show_nonconverting_candidate (tree, tree, tree, int);
> +extern bool conv_binds_to_reference_parm_p (tree, tree);
>
> /* in class.cc */
> extern tree build_vfield_ref (tree, tree);
> diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
> index ac37330527e..1a341f7e606 100644
> --- a/gcc/cp/init.cc
> +++ b/gcc/cp/init.cc
> @@ -906,7 +906,8 @@ find_uninit_fields_r (tree *tp, int *walk_subtrees, void *data)
> warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
> "reference %qD is not yet bound to a value when used "
> "here", field);
> - else if (!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
> + else if ((!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
> + && !conv_binds_to_reference_parm_p (type, init))
> warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
> "member %qD is used uninitialized", field);
> *walk_subtrees = false;
> diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
> index 89e90668c41..2fd33037bfd 100644
> --- a/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
> +++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-15.C
> @@ -65,8 +65,7 @@ struct H {
> G g;
> A a2;
> H() : g(a1) { }
> - // ??? clang++ doesn't warn here
> - H(int) : g(a2) { } // { dg-warning "member .H::a2. is used uninitialized" }
> + H(int) : g(a2) { } // { dg-bogus "member .H::a2. is used uninitialized" }
> };
>
> struct I {
> diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
> new file mode 100644
> index 00000000000..28226d8032e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-34.C
> @@ -0,0 +1,32 @@
> +// PR c++/113987
> +// { dg-do compile }
> +// { dg-options "-Wuninitialized" }
> +
> +struct t1 {
> + t1(int);
> +};
> +struct t2 {
> + t2(int&, int = 0);
> + t2(double&, int = 0);
> +};
> +struct t3 {
> + t3(int&);
> +};
> +struct t4 {};
> +void f1(int&);
> +struct t {
> + t() :
> + v1(i), // { dg-warning "is used uninitialized" }
> + v2(i),
> + v3(i),
> + v4((f1(i), t4())),
> + v5(i) {}
> + t1 v1;
> + t2 v2;
> + t3 v3;
> + t4 v4;
> + t1 v5;
> + int i;
> + int j;
> +};
> +int main() { t v1; }
>
> base-commit: ca5f509903315a56b2f306f8644544861a6525cb
On Thu, Feb 22, 2024 at 08:34:45AM +0000, Jason Merrill wrote:
> On 2/20/24 19:15, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> >
> > -- >8 --
> > This PR asks that our -Wuninitialized for mem-initializers does
> > not warn when binding a reference to an uninitialized data member.
> > We already check !INDIRECT_TYPE_P in find_uninit_fields_r, but
> > that won't catch binding a parameter of a reference type to an
> > uninitialized field, as in:
> >
> > struct S { S (int&); };
> > struct T {
> > T() : s(i) {}
> > S s;
> > int i;
> > };
> >
> > This patch adds a new function to handle this case.
>
> For type_build_ctor_call types like S, it's weird that we currently
> find_uninit_fields before building the initialization. What if we move the
> check after the build_aggr_init so we have the actual initializer instead of
> just the expression?
Thanks. I've tried but unfortunately I'm not getting anywhere. One
problem is that immediately after the find_uninit_fields call we may
change the TREE_LIST in
if (init && TREE_CODE (init) == TREE_LIST)
//...
so we'd have to cope with that somehow. Sinking find_uninit_fields
into one of the conditions below looks like a complication. Another
problem is that calling find_uninit_fields on the result of
build_aggr_init call causes a bogus warning: we create something like
E::E (&((struct F *) this)->e, ((struct F *) this)->a)
and then warn that the this object is uninitialized. So I'm not sure
if that fix would be simpler.
Marek
On 2/22/24 14:28, Marek Polacek wrote:
> On Thu, Feb 22, 2024 at 08:34:45AM +0000, Jason Merrill wrote:
>> On 2/20/24 19:15, Marek Polacek wrote:
>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>
>>> -- >8 --
>>> This PR asks that our -Wuninitialized for mem-initializers does
>>> not warn when binding a reference to an uninitialized data member.
>>> We already check !INDIRECT_TYPE_P in find_uninit_fields_r, but
>>> that won't catch binding a parameter of a reference type to an
>>> uninitialized field, as in:
>>>
>>> struct S { S (int&); };
>>> struct T {
>>> T() : s(i) {}
>>> S s;
>>> int i;
>>> };
>>>
>>> This patch adds a new function to handle this case.
>>
>> For type_build_ctor_call types like S, it's weird that we currently
>> find_uninit_fields before building the initialization. What if we move the
>> check after the build_aggr_init so we have the actual initializer instead of
>> just the expression?
>
> Thanks. I've tried but unfortunately I'm not getting anywhere. One
> problem is that immediately after the find_uninit_fields call we may
> change the TREE_LIST in
>
> if (init && TREE_CODE (init) == TREE_LIST)
> //...
>
> so we'd have to cope with that somehow. Sinking find_uninit_fields
> into one of the conditions below looks like a complication. Another
> problem is that calling find_uninit_fields on the result of
> build_aggr_init call causes a bogus warning: we create something like
> E::E (&((struct F *) this)->e, ((struct F *) this)->a)
> and then warn that the this object is uninitialized. So I'm not sure
> if that fix would be simpler.
Fair enough, the patch is OK.
Jason
@@ -14551,4 +14551,28 @@ maybe_show_nonconverting_candidate (tree to, tree from, tree arg, int flags)
"function was not considered");
}
+/* We're converting EXPR to TYPE. If that conversion involves a conversion
+ function and we're binding EXPR to a reference parameter of that function,
+ return true. */
+
+bool
+conv_binds_to_reference_parm_p (tree type, tree expr)
+{
+ conversion_obstack_sentinel cos;
+ conversion *c = implicit_conversion (type, TREE_TYPE (expr), expr,
+ /*c_cast_p=*/false, LOOKUP_NORMAL,
+ tf_none);
+ if (c && !c->bad_p && c->user_conv_p)
+ for (; c; c = next_conversion (c))
+ if (c->kind == ck_user)
+ for (z_candidate *cand = c->cand; cand; cand = cand->next)
+ if (cand->viable == 1)
+ for (size_t i = 0; i < cand->num_convs; ++i)
+ if (cand->convs[i]->kind == ck_ref_bind
+ && conv_get_original_expr (cand->convs[i]) == expr)
+ return true;
+
+ return false;
+}
+
#include "gt-cp-call.h"
@@ -6845,6 +6845,7 @@ extern void cp_warn_deprecated_use_scopes (tree);
extern tree get_function_version_dispatcher (tree);
extern bool any_template_arguments_need_structural_equality_p (tree);
extern void maybe_show_nonconverting_candidate (tree, tree, tree, int);
+extern bool conv_binds_to_reference_parm_p (tree, tree);
/* in class.cc */
extern tree build_vfield_ref (tree, tree);
@@ -906,7 +906,8 @@ find_uninit_fields_r (tree *tp, int *walk_subtrees, void *data)
warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
"reference %qD is not yet bound to a value when used "
"here", field);
- else if (!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
+ else if ((!INDIRECT_TYPE_P (type) || is_this_parameter (d->member))
+ && !conv_binds_to_reference_parm_p (type, init))
warning_at (EXPR_LOCATION (init), OPT_Wuninitialized,
"member %qD is used uninitialized", field);
*walk_subtrees = false;
@@ -65,8 +65,7 @@ struct H {
G g;
A a2;
H() : g(a1) { }
- // ??? clang++ doesn't warn here
- H(int) : g(a2) { } // { dg-warning "member .H::a2. is used uninitialized" }
+ H(int) : g(a2) { } // { dg-bogus "member .H::a2. is used uninitialized" }
};
struct I {
new file mode 100644
@@ -0,0 +1,32 @@
+// PR c++/113987
+// { dg-do compile }
+// { dg-options "-Wuninitialized" }
+
+struct t1 {
+ t1(int);
+};
+struct t2 {
+ t2(int&, int = 0);
+ t2(double&, int = 0);
+};
+struct t3 {
+ t3(int&);
+};
+struct t4 {};
+void f1(int&);
+struct t {
+ t() :
+ v1(i), // { dg-warning "is used uninitialized" }
+ v2(i),
+ v3(i),
+ v4((f1(i), t4())),
+ v5(i) {}
+ t1 v1;
+ t2 v2;
+ t3 v3;
+ t4 v4;
+ t1 v5;
+ int i;
+ int j;
+};
+int main() { t v1; }