* [PATCH] c++: suppress -Waddress warnings with *_cast [PR105569]
@ 2022-05-16 17:06 Marek Polacek
2022-05-18 13:43 ` Jason Merrill
0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2022-05-16 17:06 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
dynamic_cast can legally return nullptr, so I don't think it's helpful
for -Waddress to warn for
if (dynamic_cast<A*>(&ref))
// ...
More generally, it's likely not useful to warn for the artificial
POINTER_PLUS_EXPRs created by build_base_path.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
PR c++/105569
gcc/cp/ChangeLog:
* class.cc (build_base_path): Suppress -Waddress warning.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Waddress-9.C: New test.
---
gcc/cp/class.cc | 2 ++
gcc/testsuite/g++.dg/warn/Waddress-9.C | 34 ++++++++++++++++++++++++++
2 files changed, 36 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index 3c195b35396..06167380423 100644
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -518,6 +518,8 @@ build_base_path (enum tree_code code,
expr = build1 (NOP_EXPR, ptr_target_type, expr);
+ suppress_warning (expr, OPT_Waddress);
+
indout:
if (!want_pointer)
{
diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C
new file mode 100644
index 00000000000..2ec41949ccf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C
@@ -0,0 +1,34 @@
+// PR c++/105569
+// { dg-do compile { target c++11 } }
+// { dg-options -Waddress }
+
+class A {};
+
+class B : public virtual A {};
+
+class C : public A {};
+
+int main() {
+ B* object = new B();
+ B &ref = *object;
+
+ // -Waddress warns here
+ bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-bogus "-Waddress" }
+ bool b4 = nullptr == static_cast<A*>(&ref); // { dg-bogus "-Waddress" }
+ if (dynamic_cast<A*>(&ref)) // { dg-bogus "-Waddress" }
+ {
+ }
+ if (static_cast<A*>(&ref)) // { dg-bogus "-Waddress" }
+ {
+ }
+
+ // -Waddress doesn't warn anymore
+ auto ptr = dynamic_cast<A*>(&ref);
+ bool b2 = ptr == nullptr;
+
+ C* cobject = new C();
+ C &cref = *cobject;
+
+ // -Waddress also doesn't warn anymore
+ bool b3 = nullptr == dynamic_cast<A*>(&cref);
+}
base-commit: 682e587f1021241758f7dfe0b22651008622a312
--
2.36.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] c++: suppress -Waddress warnings with *_cast [PR105569] 2022-05-16 17:06 [PATCH] c++: suppress -Waddress warnings with *_cast [PR105569] Marek Polacek @ 2022-05-18 13:43 ` Jason Merrill 2022-05-25 20:25 ` [PATCH v2] " Marek Polacek 0 siblings, 1 reply; 6+ messages in thread From: Jason Merrill @ 2022-05-18 13:43 UTC (permalink / raw) To: Marek Polacek, GCC Patches On 5/16/22 13:06, Marek Polacek wrote: > dynamic_cast can legally return nullptr, so I don't think it's helpful > for -Waddress to warn for > > if (dynamic_cast<A*>(&ref)) > // ... > > More generally, it's likely not useful to warn for the artificial > POINTER_PLUS_EXPRs created by build_base_path. Normally the POINTER_PLUS_EXPR is guarded by if (nonnull). But build_base_path isn't adding that guard in this case because the operand is known to be a reference, which cannot be null (http://eel.is/c++draft/dcl.ref#5). So a warning is indicated for this testcase, though it would be good to give a more informative one ("comparing address of reference to null"). > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > PR c++/105569 > > gcc/cp/ChangeLog: > > * class.cc (build_base_path): Suppress -Waddress warning. > > gcc/testsuite/ChangeLog: > > * g++.dg/warn/Waddress-9.C: New test. > --- > gcc/cp/class.cc | 2 ++ > gcc/testsuite/g++.dg/warn/Waddress-9.C | 34 ++++++++++++++++++++++++++ > 2 files changed, 36 insertions(+) > create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C > > diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc > index 3c195b35396..06167380423 100644 > --- a/gcc/cp/class.cc > +++ b/gcc/cp/class.cc > @@ -518,6 +518,8 @@ build_base_path (enum tree_code code, > > expr = build1 (NOP_EXPR, ptr_target_type, expr); > > + suppress_warning (expr, OPT_Waddress); > + > indout: > if (!want_pointer) > { > diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C > new file mode 100644 > index 00000000000..2ec41949ccf > --- /dev/null > +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C > @@ -0,0 +1,34 @@ > +// PR c++/105569 > +// { dg-do compile { target c++11 } } > +// { dg-options -Waddress } > + > +class A {}; > + > +class B : public virtual A {}; > + > +class C : public A {}; > + > +int main() { > + B* object = new B(); > + B &ref = *object; > + > + // -Waddress warns here > + bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-bogus "-Waddress" } > + bool b4 = nullptr == static_cast<A*>(&ref); // { dg-bogus "-Waddress" } > + if (dynamic_cast<A*>(&ref)) // { dg-bogus "-Waddress" } > + { > + } > + if (static_cast<A*>(&ref)) // { dg-bogus "-Waddress" } > + { > + } > + > + // -Waddress doesn't warn anymore > + auto ptr = dynamic_cast<A*>(&ref); > + bool b2 = ptr == nullptr; > + > + C* cobject = new C(); > + C &cref = *cobject; > + > + // -Waddress also doesn't warn anymore > + bool b3 = nullptr == dynamic_cast<A*>(&cref); > +} > > base-commit: 682e587f1021241758f7dfe0b22651008622a312 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] c++: suppress -Waddress warnings with *_cast [PR105569] 2022-05-18 13:43 ` Jason Merrill @ 2022-05-25 20:25 ` Marek Polacek 2022-05-26 13:26 ` Jason Merrill 0 siblings, 1 reply; 6+ messages in thread From: Marek Polacek @ 2022-05-25 20:25 UTC (permalink / raw) To: Jason Merrill; +Cc: GCC Patches On Wed, May 18, 2022 at 09:43:47AM -0400, Jason Merrill wrote: > On 5/16/22 13:06, Marek Polacek wrote: > > dynamic_cast can legally return nullptr, so I don't think it's helpful > > for -Waddress to warn for > > > > if (dynamic_cast<A*>(&ref)) > > // ... > > > > More generally, it's likely not useful to warn for the artificial > > POINTER_PLUS_EXPRs created by build_base_path. > > Normally the POINTER_PLUS_EXPR is guarded by if (nonnull). But > build_base_path isn't adding that guard in this case because the operand is > known to be a reference, which cannot be null > (http://eel.is/c++draft/dcl.ref#5). So a warning is indicated for this > testcase, though it would be good to give a more informative one ("comparing > address of reference to null"). Ah, got it. How about this patch instead? Thanks, -- >8 -- This patch improves the diagnostic for -Waddress when it warns for if (dynamic_cast<A*>(&ref)) // ... where 'ref' is a reference, which cannot be null. In particular, it changes warning: comparing the result of pointer addition '(((A*)ref) + ((sizetype)(*(long int*)((& ref)->B::_vptr.B + -24))))' and NULL to warning: comparing address of reference 'ref' to null PR c++/105569 gcc/cp/ChangeLog: * typeck.cc (warn_for_null_address): Improve the warning when the POINTER_PLUS_EXPR's base is of reference type. gcc/testsuite/ChangeLog: * g++.dg/warn/Waddress-9.C: New test. --- gcc/cp/typeck.cc | 12 ++++++++-- gcc/testsuite/g++.dg/warn/Waddress-9.C | 31 ++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc index 385cdf4d733..0837f2484ba 100644 --- a/gcc/cp/typeck.cc +++ b/gcc/cp/typeck.cc @@ -4757,8 +4757,16 @@ warn_for_null_address (location_t location, tree op, tsubst_flags_t complain) tree off = TREE_OPERAND (cop, 1); if (!integer_zerop (off) && !warning_suppressed_p (cop, OPT_Waddress)) - warning_at (location, OPT_Waddress, "comparing the result of pointer " - "addition %qE and NULL", cop); + { + tree base = TREE_OPERAND (cop, 0); + STRIP_NOPS (base); + if (TYPE_REF_P (TREE_TYPE (base))) + warning_at (location, OPT_Waddress, "comparing address of " + "reference %qE and NULL", base); + else + warning_at (location, OPT_Waddress, "comparing the result of " + "pointer addition %qE and NULL", cop); + } return; } else if (CONVERT_EXPR_P (op) diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C new file mode 100644 index 00000000000..a3654ff1f91 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C @@ -0,0 +1,31 @@ +// PR c++/105569 +// { dg-do compile { target c++11 } } +// { dg-options -Waddress } + +class A {}; + +class B : public virtual A {}; + +class C : public A {}; + +int main() { + B* object = new B(); + B &ref = *object; + + bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } + bool b4 = nullptr == static_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } + if (dynamic_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } + { + } + if (static_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } + { + } + + auto ptr = dynamic_cast<A*>(&ref); + bool b2 = ptr == nullptr; + + C* cobject = new C(); + C &cref = *cobject; + + bool b3 = nullptr == dynamic_cast<A*>(&cref); +} base-commit: 34970d08c6297e12f3f9117b6ac19fb2de522e24 -- 2.36.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] c++: suppress -Waddress warnings with *_cast [PR105569] 2022-05-25 20:25 ` [PATCH v2] " Marek Polacek @ 2022-05-26 13:26 ` Jason Merrill 2022-05-26 13:33 ` Marek Polacek 0 siblings, 1 reply; 6+ messages in thread From: Jason Merrill @ 2022-05-26 13:26 UTC (permalink / raw) To: Marek Polacek; +Cc: GCC Patches On 5/25/22 16:25, Marek Polacek wrote: > On Wed, May 18, 2022 at 09:43:47AM -0400, Jason Merrill wrote: >> On 5/16/22 13:06, Marek Polacek wrote: >>> dynamic_cast can legally return nullptr, so I don't think it's helpful >>> for -Waddress to warn for >>> >>> if (dynamic_cast<A*>(&ref)) >>> // ... >>> >>> More generally, it's likely not useful to warn for the artificial >>> POINTER_PLUS_EXPRs created by build_base_path. >> >> Normally the POINTER_PLUS_EXPR is guarded by if (nonnull). But >> build_base_path isn't adding that guard in this case because the operand is >> known to be a reference, which cannot be null >> (http://eel.is/c++draft/dcl.ref#5). So a warning is indicated for this >> testcase, though it would be good to give a more informative one ("comparing >> address of reference to null"). > > Ah, got it. How about this patch instead? Thanks, Do we also warn about plain &ref == nullptr? > -- >8 -- > This patch improves the diagnostic for -Waddress when it warns for > > if (dynamic_cast<A*>(&ref)) > // ... > > where 'ref' is a reference, which cannot be null. In particular, it > changes > warning: comparing the result of pointer addition '(((A*)ref) + ((sizetype)(*(long int*)((& ref)->B::_vptr.B + -24))))' and NULL > to > warning: comparing address of reference 'ref' to null > > PR c++/105569 > > gcc/cp/ChangeLog: > > * typeck.cc (warn_for_null_address): Improve the warning when > the POINTER_PLUS_EXPR's base is of reference type. > > gcc/testsuite/ChangeLog: > > * g++.dg/warn/Waddress-9.C: New test. > --- > gcc/cp/typeck.cc | 12 ++++++++-- > gcc/testsuite/g++.dg/warn/Waddress-9.C | 31 ++++++++++++++++++++++++++ > 2 files changed, 41 insertions(+), 2 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C > > diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc > index 385cdf4d733..0837f2484ba 100644 > --- a/gcc/cp/typeck.cc > +++ b/gcc/cp/typeck.cc > @@ -4757,8 +4757,16 @@ warn_for_null_address (location_t location, tree op, tsubst_flags_t complain) > tree off = TREE_OPERAND (cop, 1); > if (!integer_zerop (off) > && !warning_suppressed_p (cop, OPT_Waddress)) > - warning_at (location, OPT_Waddress, "comparing the result of pointer " > - "addition %qE and NULL", cop); > + { > + tree base = TREE_OPERAND (cop, 0); > + STRIP_NOPS (base); > + if (TYPE_REF_P (TREE_TYPE (base))) > + warning_at (location, OPT_Waddress, "comparing address of " > + "reference %qE and NULL", base); > + else > + warning_at (location, OPT_Waddress, "comparing the result of " > + "pointer addition %qE and NULL", cop); > + } > return; > } > else if (CONVERT_EXPR_P (op) > diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C > new file mode 100644 > index 00000000000..a3654ff1f91 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C > @@ -0,0 +1,31 @@ > +// PR c++/105569 > +// { dg-do compile { target c++11 } } > +// { dg-options -Waddress } > + > +class A {}; > + > +class B : public virtual A {}; > + > +class C : public A {}; > + > +int main() { > + B* object = new B(); > + B &ref = *object; > + > + bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } > + bool b4 = nullptr == static_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } > + if (dynamic_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } > + { > + } > + if (static_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } > + { > + } > + > + auto ptr = dynamic_cast<A*>(&ref); > + bool b2 = ptr == nullptr; > + > + C* cobject = new C(); > + C &cref = *cobject; > + > + bool b3 = nullptr == dynamic_cast<A*>(&cref); > +} > > base-commit: 34970d08c6297e12f3f9117b6ac19fb2de522e24 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] c++: suppress -Waddress warnings with *_cast [PR105569] 2022-05-26 13:26 ` Jason Merrill @ 2022-05-26 13:33 ` Marek Polacek 2022-05-26 20:34 ` Jason Merrill 0 siblings, 1 reply; 6+ messages in thread From: Marek Polacek @ 2022-05-26 13:33 UTC (permalink / raw) To: Jason Merrill; +Cc: GCC Patches On Thu, May 26, 2022 at 09:26:16AM -0400, Jason Merrill wrote: > On 5/25/22 16:25, Marek Polacek wrote: > > On Wed, May 18, 2022 at 09:43:47AM -0400, Jason Merrill wrote: > > > On 5/16/22 13:06, Marek Polacek wrote: > > > > dynamic_cast can legally return nullptr, so I don't think it's helpful > > > > for -Waddress to warn for > > > > > > > > if (dynamic_cast<A*>(&ref)) > > > > // ... > > > > > > > > More generally, it's likely not useful to warn for the artificial > > > > POINTER_PLUS_EXPRs created by build_base_path. > > > > > > Normally the POINTER_PLUS_EXPR is guarded by if (nonnull). But > > > build_base_path isn't adding that guard in this case because the operand is > > > known to be a reference, which cannot be null > > > (http://eel.is/c++draft/dcl.ref#5). So a warning is indicated for this > > > testcase, though it would be good to give a more informative one ("comparing > > > address of reference to null"). > > > > Ah, got it. How about this patch instead? Thanks, > > Do we also warn about plain &ref == nullptr? Yeah, with different wording: p.C:5:12: warning: the compiler can assume that the address of ‘ref’ will never be NULL [-Waddress] 5 | if (&ref == nullptr) | ~~~~~^~~~~~~~~~ warn/Walways-true-3.C tests this. > > -- >8 -- > > This patch improves the diagnostic for -Waddress when it warns for > > > > if (dynamic_cast<A*>(&ref)) > > // ... > > > > where 'ref' is a reference, which cannot be null. In particular, it > > changes > > warning: comparing the result of pointer addition '(((A*)ref) + ((sizetype)(*(long int*)((& ref)->B::_vptr.B + -24))))' and NULL > > to > > warning: comparing address of reference 'ref' to null > > > > PR c++/105569 > > > > gcc/cp/ChangeLog: > > > > * typeck.cc (warn_for_null_address): Improve the warning when > > the POINTER_PLUS_EXPR's base is of reference type. > > > > gcc/testsuite/ChangeLog: > > > > * g++.dg/warn/Waddress-9.C: New test. > > --- > > gcc/cp/typeck.cc | 12 ++++++++-- > > gcc/testsuite/g++.dg/warn/Waddress-9.C | 31 ++++++++++++++++++++++++++ > > 2 files changed, 41 insertions(+), 2 deletions(-) > > create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C > > > > diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc > > index 385cdf4d733..0837f2484ba 100644 > > --- a/gcc/cp/typeck.cc > > +++ b/gcc/cp/typeck.cc > > @@ -4757,8 +4757,16 @@ warn_for_null_address (location_t location, tree op, tsubst_flags_t complain) > > tree off = TREE_OPERAND (cop, 1); > > if (!integer_zerop (off) > > && !warning_suppressed_p (cop, OPT_Waddress)) > > - warning_at (location, OPT_Waddress, "comparing the result of pointer " > > - "addition %qE and NULL", cop); > > + { > > + tree base = TREE_OPERAND (cop, 0); > > + STRIP_NOPS (base); > > + if (TYPE_REF_P (TREE_TYPE (base))) > > + warning_at (location, OPT_Waddress, "comparing address of " > > + "reference %qE and NULL", base); > > + else > > + warning_at (location, OPT_Waddress, "comparing the result of " > > + "pointer addition %qE and NULL", cop); > > + } > > return; > > } > > else if (CONVERT_EXPR_P (op) > > diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C > > new file mode 100644 > > index 00000000000..a3654ff1f91 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C > > @@ -0,0 +1,31 @@ > > +// PR c++/105569 > > +// { dg-do compile { target c++11 } } > > +// { dg-options -Waddress } > > + > > +class A {}; > > + > > +class B : public virtual A {}; > > + > > +class C : public A {}; > > + > > +int main() { > > + B* object = new B(); > > + B &ref = *object; > > + > > + bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } > > + bool b4 = nullptr == static_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } > > + if (dynamic_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } > > + { > > + } > > + if (static_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } > > + { > > + } > > + > > + auto ptr = dynamic_cast<A*>(&ref); > > + bool b2 = ptr == nullptr; > > + > > + C* cobject = new C(); > > + C &cref = *cobject; > > + > > + bool b3 = nullptr == dynamic_cast<A*>(&cref); > > +} > > > > base-commit: 34970d08c6297e12f3f9117b6ac19fb2de522e24 > Marek ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] c++: suppress -Waddress warnings with *_cast [PR105569] 2022-05-26 13:33 ` Marek Polacek @ 2022-05-26 20:34 ` Jason Merrill 0 siblings, 0 replies; 6+ messages in thread From: Jason Merrill @ 2022-05-26 20:34 UTC (permalink / raw) To: Marek Polacek; +Cc: GCC Patches On 5/26/22 09:33, Marek Polacek wrote: > On Thu, May 26, 2022 at 09:26:16AM -0400, Jason Merrill wrote: >> On 5/25/22 16:25, Marek Polacek wrote: >>> On Wed, May 18, 2022 at 09:43:47AM -0400, Jason Merrill wrote: >>>> On 5/16/22 13:06, Marek Polacek wrote: >>>>> dynamic_cast can legally return nullptr, so I don't think it's helpful >>>>> for -Waddress to warn for >>>>> >>>>> if (dynamic_cast<A*>(&ref)) >>>>> // ... >>>>> >>>>> More generally, it's likely not useful to warn for the artificial >>>>> POINTER_PLUS_EXPRs created by build_base_path. >>>> >>>> Normally the POINTER_PLUS_EXPR is guarded by if (nonnull). But >>>> build_base_path isn't adding that guard in this case because the operand is >>>> known to be a reference, which cannot be null >>>> (http://eel.is/c++draft/dcl.ref#5). So a warning is indicated for this >>>> testcase, though it would be good to give a more informative one ("comparing >>>> address of reference to null"). >>> >>> Ah, got it. How about this patch instead? Thanks, >> >> Do we also warn about plain &ref == nullptr? > > Yeah, with different wording: > > p.C:5:12: warning: the compiler can assume that the address of ‘ref’ will never be NULL [-Waddress] > 5 | if (&ref == nullptr) > | ~~~~~^~~~~~~~~~ > > warn/Walways-true-3.C tests this. Let's use that wording in this case as well, then. OK with that change. >>> -- >8 -- >>> This patch improves the diagnostic for -Waddress when it warns for >>> >>> if (dynamic_cast<A*>(&ref)) >>> // ... >>> >>> where 'ref' is a reference, which cannot be null. In particular, it >>> changes >>> warning: comparing the result of pointer addition '(((A*)ref) + ((sizetype)(*(long int*)((& ref)->B::_vptr.B + -24))))' and NULL >>> to >>> warning: comparing address of reference 'ref' to null >>> >>> PR c++/105569 >>> >>> gcc/cp/ChangeLog: >>> >>> * typeck.cc (warn_for_null_address): Improve the warning when >>> the POINTER_PLUS_EXPR's base is of reference type. >>> >>> gcc/testsuite/ChangeLog: >>> >>> * g++.dg/warn/Waddress-9.C: New test. >>> --- >>> gcc/cp/typeck.cc | 12 ++++++++-- >>> gcc/testsuite/g++.dg/warn/Waddress-9.C | 31 ++++++++++++++++++++++++++ >>> 2 files changed, 41 insertions(+), 2 deletions(-) >>> create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C >>> >>> diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc >>> index 385cdf4d733..0837f2484ba 100644 >>> --- a/gcc/cp/typeck.cc >>> +++ b/gcc/cp/typeck.cc >>> @@ -4757,8 +4757,16 @@ warn_for_null_address (location_t location, tree op, tsubst_flags_t complain) >>> tree off = TREE_OPERAND (cop, 1); >>> if (!integer_zerop (off) >>> && !warning_suppressed_p (cop, OPT_Waddress)) >>> - warning_at (location, OPT_Waddress, "comparing the result of pointer " >>> - "addition %qE and NULL", cop); >>> + { >>> + tree base = TREE_OPERAND (cop, 0); >>> + STRIP_NOPS (base); >>> + if (TYPE_REF_P (TREE_TYPE (base))) >>> + warning_at (location, OPT_Waddress, "comparing address of " >>> + "reference %qE and NULL", base); >>> + else >>> + warning_at (location, OPT_Waddress, "comparing the result of " >>> + "pointer addition %qE and NULL", cop); >>> + } >>> return; >>> } >>> else if (CONVERT_EXPR_P (op) >>> diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C >>> new file mode 100644 >>> index 00000000000..a3654ff1f91 >>> --- /dev/null >>> +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C >>> @@ -0,0 +1,31 @@ >>> +// PR c++/105569 >>> +// { dg-do compile { target c++11 } } >>> +// { dg-options -Waddress } >>> + >>> +class A {}; >>> + >>> +class B : public virtual A {}; >>> + >>> +class C : public A {}; >>> + >>> +int main() { >>> + B* object = new B(); >>> + B &ref = *object; >>> + >>> + bool b = nullptr == dynamic_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } >>> + bool b4 = nullptr == static_cast<A*>(&ref); // { dg-warning "comparing address of reference .ref. and NULL" } >>> + if (dynamic_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } >>> + { >>> + } >>> + if (static_cast<A*>(&ref)) // { dg-warning "comparing address of reference .ref. and NULL" } >>> + { >>> + } >>> + >>> + auto ptr = dynamic_cast<A*>(&ref); >>> + bool b2 = ptr == nullptr; >>> + >>> + C* cobject = new C(); >>> + C &cref = *cobject; >>> + >>> + bool b3 = nullptr == dynamic_cast<A*>(&cref); >>> +} >>> >>> base-commit: 34970d08c6297e12f3f9117b6ac19fb2de522e24 >> > > Marek > ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-05-26 20:35 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-05-16 17:06 [PATCH] c++: suppress -Waddress warnings with *_cast [PR105569] Marek Polacek 2022-05-18 13:43 ` Jason Merrill 2022-05-25 20:25 ` [PATCH v2] " Marek Polacek 2022-05-26 13:26 ` Jason Merrill 2022-05-26 13:33 ` Marek Polacek 2022-05-26 20:34 ` Jason Merrill
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