[v2] c++: fix ICE with -Wduplicated-cond [PR107593]
Commit Message
On Fri, Jan 27, 2023 at 06:17:00PM -0500, Patrick Palka wrote:
> On Fri, 27 Jan 2023, Marek Polacek wrote:
>
> > On Fri, Jan 27, 2023 at 05:15:00PM -0500, Patrick Palka wrote:
> > > On Thu, 26 Jan 2023, Marek Polacek via Gcc-patches wrote:
> > >
> > > > Here we crash because a CAST_EXPR, representing T(), doesn't have
> > > > its operand, and operand_equal_p's STRIP_ANY_LOCATION_WRAPPER doesn't
> > > > expect that. (o_e_p is called from warn_duplicated_cond_add_or_warn.)
> > > >
> > > > In the past we've adjusted o_e_p to better cope with template codes,
> > > > but in this case I think we just want to avoid attempting to warn
> > > > about inst-dependent expressions; I don't think I've ever envisioned
> > > > -Wduplicated-cond to warn about them.
> > > >
> > > > The ICE started with r12-6022, two-stage name lookup for overloaded
> > > > operators, which gave dependent operators a TREE_TYPE (in particular,
> > > > DEPENDENT_OPERATOR_TYPE), so we no longer bail out here in o_e_p:
> > > >
> > > > /* Similar, if either does not have a type (like a template id),
> > > > they aren't equal. */
> > > > if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
> > > > return false;
> > > >
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > >
> > > > PR c++/107593
> > > >
> > > > gcc/cp/ChangeLog:
> > > >
> > > > * parser.cc (cp_parser_selection_statement): Don't do
> > > > -Wduplicated-cond when the condition is dependent.
> > > >
> > > > gcc/testsuite/ChangeLog:
> > > >
> > > > * g++.dg/warn/Wduplicated-cond3.C: New test.
> > > > ---
> > > > gcc/cp/parser.cc | 3 +-
> > > > gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C | 38 +++++++++++++++++++
> > > > 2 files changed, 40 insertions(+), 1 deletion(-)
> > > > create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
> > > >
> > > > diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> > > > index 4cdc1cd472f..3df85d49e16 100644
> > > > --- a/gcc/cp/parser.cc
> > > > +++ b/gcc/cp/parser.cc
> > > > @@ -13209,7 +13209,8 @@ cp_parser_selection_statement (cp_parser* parser, bool *if_p,
> > > > /* Add the condition. */
> > > > condition = finish_if_stmt_cond (condition, statement);
> > > >
> > > > - if (warn_duplicated_cond)
> > > > + if (warn_duplicated_cond
> > > > + && !instantiation_dependent_expression_p (condition))
> > > > warn_duplicated_cond_add_or_warn (token->location, condition,
> > > > &chain);
> > >
> > > I noticed warn_duplicated_cond_add_or_warn already has logic to handle
> > > TREE_SIDE_EFFECTS conditions by invaliding the entire chain. I wonder
> > > if we'd want to do the same for instantiation-dep conditions?
> >
> > warn_duplicated_cond_add_or_warn lives in c-family/c-warn.cc so I can't
> > use instantiation_dependent_expression_p there. Sure, I could write a
> > C++ wrapper but with my patch we just won't add CONDITION to the chain
> > which I thought would work just as well.
>
> Ah that's unfortunate :( ISTM desirable to conservatively assume an
> inst-dep cond has side effects though (possibly directly from
> cp_parser_selection_statement), to avoid false positives as in:
>
> int n;
>
> template<class T> bool g() { n = 42; }
>
> template<class T>
> void f() {
> if (n)
> ;
> else if (g<T>())
> ;
> else if (n)
> ;
> }
You're right, we shouldn't warn there. So I've just added a new param
with a default argument. A new PR was just opened for the same problem
so I've added another test.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
Here we crash because a CAST_EXPR, representing T(), doesn't have
its operand, and operand_equal_p's STRIP_ANY_LOCATION_WRAPPER doesn't
expect that. (o_e_p is called from warn_duplicated_cond_add_or_warn.)
In the past we've adjusted o_e_p to better cope with template codes,
but in this case I think we just want to avoid attempting to warn
about inst-dependent expressions; I don't think I've ever envisioned
-Wduplicated-cond to warn about them. Also destroy the chain when
an inst-dependent expression is encountered to not warn in
Wduplicated-cond4.C.
The ICE started with r12-6022, two-stage name lookup for overloaded
operators, which gave dependent operators a TREE_TYPE (in particular,
DEPENDENT_OPERATOR_TYPE), so we no longer bail out here in o_e_p:
/* Similar, if either does not have a type (like a template id),
they aren't equal. */
if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
return false;
PR c++/107593
PR c++/108597
gcc/c-family/ChangeLog:
* c-common.h (warn_duplicated_cond_add_or_warn): New parameter.
* c-warn.cc (warn_duplicated_cond_add_or_warn): Add new parameter.
Use it.
gcc/cp/ChangeLog:
* parser.cc (cp_parser_selection_statement): Pass the result of
instantiation_dependent_expression_p down to
warn_duplicated_cond_add_or_warn.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wduplicated-cond3.C: New test.
* g++.dg/warn/Wduplicated-cond4.C: New test.
* g++.dg/warn/Wduplicated-cond5.C: New test.
---
gcc/c-family/c-common.h | 3 +-
gcc/c-family/c-warn.cc | 5 ++-
gcc/cp/parser.cc | 8 +++-
gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C | 38 +++++++++++++++++++
gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C | 17 +++++++++
gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C | 16 ++++++++
6 files changed, 82 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C
create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C
base-commit: 5f8950b403f6351f125d8281d2e7430a43e7d125
Comments
On 1/30/23 11:00, Marek Polacek wrote:
> On Fri, Jan 27, 2023 at 06:17:00PM -0500, Patrick Palka wrote:
>> On Fri, 27 Jan 2023, Marek Polacek wrote:
>>
>>> On Fri, Jan 27, 2023 at 05:15:00PM -0500, Patrick Palka wrote:
>>>> On Thu, 26 Jan 2023, Marek Polacek via Gcc-patches wrote:
>>>>
>>>>> Here we crash because a CAST_EXPR, representing T(), doesn't have
>>>>> its operand, and operand_equal_p's STRIP_ANY_LOCATION_WRAPPER doesn't
>>>>> expect that. (o_e_p is called from warn_duplicated_cond_add_or_warn.)
>>>>>
>>>>> In the past we've adjusted o_e_p to better cope with template codes,
>>>>> but in this case I think we just want to avoid attempting to warn
>>>>> about inst-dependent expressions; I don't think I've ever envisioned
>>>>> -Wduplicated-cond to warn about them.
>>>>>
>>>>> The ICE started with r12-6022, two-stage name lookup for overloaded
>>>>> operators, which gave dependent operators a TREE_TYPE (in particular,
>>>>> DEPENDENT_OPERATOR_TYPE), so we no longer bail out here in o_e_p:
>>>>>
>>>>> /* Similar, if either does not have a type (like a template id),
>>>>> they aren't equal. */
>>>>> if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
>>>>> return false;
>>>>>
>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>>
>>>>> PR c++/107593
>>>>>
>>>>> gcc/cp/ChangeLog:
>>>>>
>>>>> * parser.cc (cp_parser_selection_statement): Don't do
>>>>> -Wduplicated-cond when the condition is dependent.
>>>>>
>>>>> gcc/testsuite/ChangeLog:
>>>>>
>>>>> * g++.dg/warn/Wduplicated-cond3.C: New test.
>>>>> ---
>>>>> gcc/cp/parser.cc | 3 +-
>>>>> gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C | 38 +++++++++++++++++++
>>>>> 2 files changed, 40 insertions(+), 1 deletion(-)
>>>>> create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
>>>>>
>>>>> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
>>>>> index 4cdc1cd472f..3df85d49e16 100644
>>>>> --- a/gcc/cp/parser.cc
>>>>> +++ b/gcc/cp/parser.cc
>>>>> @@ -13209,7 +13209,8 @@ cp_parser_selection_statement (cp_parser* parser, bool *if_p,
>>>>> /* Add the condition. */
>>>>> condition = finish_if_stmt_cond (condition, statement);
>>>>>
>>>>> - if (warn_duplicated_cond)
>>>>> + if (warn_duplicated_cond
>>>>> + && !instantiation_dependent_expression_p (condition))
>>>>> warn_duplicated_cond_add_or_warn (token->location, condition,
>>>>> &chain);
>>>>
>>>> I noticed warn_duplicated_cond_add_or_warn already has logic to handle
>>>> TREE_SIDE_EFFECTS conditions by invaliding the entire chain. I wonder
>>>> if we'd want to do the same for instantiation-dep conditions?
>>>
>>> warn_duplicated_cond_add_or_warn lives in c-family/c-warn.cc so I can't
>>> use instantiation_dependent_expression_p there. Sure, I could write a
>>> C++ wrapper but with my patch we just won't add CONDITION to the chain
>>> which I thought would work just as well.
Or maybe define instantiation_dependent_expression_p in the C front-end
to just return false?
>> Ah that's unfortunate :( ISTM desirable to conservatively assume an
>> inst-dep cond has side effects though (possibly directly from
>> cp_parser_selection_statement), to avoid false positives as in:
>>
>> int n;
>>
>> template<class T> bool g() { n = 42; }
>>
>> template<class T>
>> void f() {
>> if (n)
>> ;
>> else if (g<T>())
>> ;
>> else if (n)
>> ;
>> }
>
> You're right, we shouldn't warn there. So I've just added a new param
> with a default argument. A new PR was just opened for the same problem
> so I've added another test.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> -- >8 --
> Here we crash because a CAST_EXPR, representing T(), doesn't have
> its operand, and operand_equal_p's STRIP_ANY_LOCATION_WRAPPER doesn't
> expect that. (o_e_p is called from warn_duplicated_cond_add_or_warn.)
>
> In the past we've adjusted o_e_p to better cope with template codes,
> but in this case I think we just want to avoid attempting to warn
> about inst-dependent expressions; I don't think I've ever envisioned
> -Wduplicated-cond to warn about them. Also destroy the chain when
> an inst-dependent expression is encountered to not warn in
> Wduplicated-cond4.C.
>
> The ICE started with r12-6022, two-stage name lookup for overloaded
> operators, which gave dependent operators a TREE_TYPE (in particular,
> DEPENDENT_OPERATOR_TYPE), so we no longer bail out here in o_e_p:
>
> /* Similar, if either does not have a type (like a template id),
> they aren't equal. */
> if (!TREE_TYPE (arg0) || !TREE_TYPE (arg1))
> return false;
>
> PR c++/107593
> PR c++/108597
>
> gcc/c-family/ChangeLog:
>
> * c-common.h (warn_duplicated_cond_add_or_warn): New parameter.
> * c-warn.cc (warn_duplicated_cond_add_or_warn): Add new parameter.
> Use it.
>
> gcc/cp/ChangeLog:
>
> * parser.cc (cp_parser_selection_statement): Pass the result of
> instantiation_dependent_expression_p down to
> warn_duplicated_cond_add_or_warn.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/warn/Wduplicated-cond3.C: New test.
> * g++.dg/warn/Wduplicated-cond4.C: New test.
> * g++.dg/warn/Wduplicated-cond5.C: New test.
> ---
> gcc/c-family/c-common.h | 3 +-
> gcc/c-family/c-warn.cc | 5 ++-
> gcc/cp/parser.cc | 8 +++-
> gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C | 38 +++++++++++++++++++
> gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C | 17 +++++++++
> gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C | 16 ++++++++
> 6 files changed, 82 insertions(+), 5 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
> create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C
> create mode 100644 gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C
>
> diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
> index bb6271d4a83..a9b47e15894 100644
> --- a/gcc/c-family/c-common.h
> +++ b/gcc/c-family/c-common.h
> @@ -1514,7 +1514,8 @@ extern void maybe_record_typedef_use (tree);
> extern void maybe_warn_unused_local_typedefs (void);
> extern void maybe_warn_bool_compare (location_t, enum tree_code, tree, tree);
> extern bool maybe_warn_shift_overflow (location_t, tree, tree);
> -extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **);
> +extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **,
> + bool = false);
> extern bool diagnose_mismatched_attributes (tree, tree);
> extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
> extern void warn_for_multistatement_macros (location_t, location_t,
> diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
> index 5ed7bcab16a..b7621656f89 100644
> --- a/gcc/c-family/c-warn.cc
> +++ b/gcc/c-family/c-warn.cc
> @@ -2529,13 +2529,14 @@ maybe_warn_unused_local_typedefs (void)
> of COND. */
>
> void
> -warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain)
> +warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain,
> + bool dependent_p /*=false*/)
> {
> /* No chain has been created yet. Do nothing. */
> if (*chain == NULL)
> return;
>
> - if (TREE_SIDE_EFFECTS (cond))
> + if (dependent_p || TREE_SIDE_EFFECTS (cond))
> {
> /* Uh-oh! This condition has a side-effect, thus invalidates
> the whole chain. */
> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> index 4cdc1cd472f..d62db229518 100644
> --- a/gcc/cp/parser.cc
> +++ b/gcc/cp/parser.cc
> @@ -13210,8 +13210,12 @@ cp_parser_selection_statement (cp_parser* parser, bool *if_p,
> condition = finish_if_stmt_cond (condition, statement);
>
> if (warn_duplicated_cond)
> - warn_duplicated_cond_add_or_warn (token->location, condition,
> - &chain);
> + {
> + const bool dep
> + = instantiation_dependent_expression_p (condition);
> + warn_duplicated_cond_add_or_warn (token->location, condition,
> + &chain, dep);
> + }
>
> /* Parse the then-clause. */
> in_statement = parser->in_statement;
> diff --git a/gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C b/gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
> new file mode 100644
> index 00000000000..3da054e5485
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wduplicated-cond3.C
> @@ -0,0 +1,38 @@
> +// PR c++/107593
> +// { dg-do compile }
> +// { dg-options "-Wduplicated-cond" }
> +
> +template <typename T>
> +void
> +foo ()
> +{
> + if (T() && T() && int())
> + ;
> + else if (T() && T() && int())
> + ;
> +}
> +
> +template <typename T>
> +void bar(T a)
> +{
> + if (a)
> + ;
> + else if (a)
> + ;
> +}
> +
> +template <typename>
> +void baz(int a)
> +{
> + if (a)
> + ;
> + else if (a) // { dg-warning "duplicated" }
> + ;
> +}
> +void
> +f ()
> +{
> + foo<int>();
> + bar(1);
> + baz<int>(1);
> +}
> diff --git a/gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C b/gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C
> new file mode 100644
> index 00000000000..41bb9f09b4f
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wduplicated-cond4.C
> @@ -0,0 +1,17 @@
> +// PR c++/107593
> +// { dg-do compile }
> +// { dg-options "-Wduplicated-cond" }
> +
> +int n;
> +
> +template<class T> bool g() { n = 42; return false; }
> +
> +template<class T>
> +void f() {
> + if (n)
> + ;
> + else if (g<T>())
> + ;
> + else if (n)
> + ;
> +}
> diff --git a/gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C b/gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C
> new file mode 100644
> index 00000000000..23a0bf212b5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wduplicated-cond5.C
> @@ -0,0 +1,16 @@
> +// PR c++/108597
> +// { dg-do compile }
> +// { dg-options "-Wduplicated-cond" }
> +
> +template <typename T>
> +struct MyStruct {
> +
> + void check(int &x) {
> + if (&x == &_a) {
> + } else if (&x == &_b) {
> + }
> + }
> +
> + int _a;
> + int _b;
> +};
>
> base-commit: 5f8950b403f6351f125d8281d2e7430a43e7d125
@@ -1514,7 +1514,8 @@ extern void maybe_record_typedef_use (tree);
extern void maybe_warn_unused_local_typedefs (void);
extern void maybe_warn_bool_compare (location_t, enum tree_code, tree, tree);
extern bool maybe_warn_shift_overflow (location_t, tree, tree);
-extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **);
+extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **,
+ bool = false);
extern bool diagnose_mismatched_attributes (tree, tree);
extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
extern void warn_for_multistatement_macros (location_t, location_t,
@@ -2529,13 +2529,14 @@ maybe_warn_unused_local_typedefs (void)
of COND. */
void
-warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain)
+warn_duplicated_cond_add_or_warn (location_t loc, tree cond, vec<tree> **chain,
+ bool dependent_p /*=false*/)
{
/* No chain has been created yet. Do nothing. */
if (*chain == NULL)
return;
- if (TREE_SIDE_EFFECTS (cond))
+ if (dependent_p || TREE_SIDE_EFFECTS (cond))
{
/* Uh-oh! This condition has a side-effect, thus invalidates
the whole chain. */
@@ -13210,8 +13210,12 @@ cp_parser_selection_statement (cp_parser* parser, bool *if_p,
condition = finish_if_stmt_cond (condition, statement);
if (warn_duplicated_cond)
- warn_duplicated_cond_add_or_warn (token->location, condition,
- &chain);
+ {
+ const bool dep
+ = instantiation_dependent_expression_p (condition);
+ warn_duplicated_cond_add_or_warn (token->location, condition,
+ &chain, dep);
+ }
/* Parse the then-clause. */
in_statement = parser->in_statement;
new file mode 100644
@@ -0,0 +1,38 @@
+// PR c++/107593
+// { dg-do compile }
+// { dg-options "-Wduplicated-cond" }
+
+template <typename T>
+void
+foo ()
+{
+ if (T() && T() && int())
+ ;
+ else if (T() && T() && int())
+ ;
+}
+
+template <typename T>
+void bar(T a)
+{
+ if (a)
+ ;
+ else if (a)
+ ;
+}
+
+template <typename>
+void baz(int a)
+{
+ if (a)
+ ;
+ else if (a) // { dg-warning "duplicated" }
+ ;
+}
+void
+f ()
+{
+ foo<int>();
+ bar(1);
+ baz<int>(1);
+}
new file mode 100644
@@ -0,0 +1,17 @@
+// PR c++/107593
+// { dg-do compile }
+// { dg-options "-Wduplicated-cond" }
+
+int n;
+
+template<class T> bool g() { n = 42; return false; }
+
+template<class T>
+void f() {
+ if (n)
+ ;
+ else if (g<T>())
+ ;
+ else if (n)
+ ;
+}
new file mode 100644
@@ -0,0 +1,16 @@
+// PR c++/108597
+// { dg-do compile }
+// { dg-options "-Wduplicated-cond" }
+
+template <typename T>
+struct MyStruct {
+
+ void check(int &x) {
+ if (&x == &_a) {
+ } else if (&x == &_b) {
+ }
+ }
+
+ int _a;
+ int _b;
+};