* [PATCH] c++: Fix unnecessary error when top-level cv-qualifiers is dropped [PR101783]
@ 2021-08-10 5:36 nick huang
2021-08-24 15:29 ` Jonathan Wakely
2021-08-28 11:54 ` [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] nick huang
0 siblings, 2 replies; 5+ messages in thread
From: nick huang @ 2021-08-10 5:36 UTC (permalink / raw)
To: gcc-patches
The root cause of this bug is that it considers reference with cv-qualifiers
as an error by generating value for variable "bad_quals". However, this is
not correct for case of typedef. Here I quote spec:
"Cv-qualified references are ill-formed except when the cv-qualifiers
are introduced through the use of a typedef-name ([dcl.typedef],
[temp.param]) or decltype-specifier ([dcl.type.decltype]),
in which case the cv-qualifiers are ignored."
2021-08-09 Qingzhe Huang <nickhuang99@hotmail.com>
PR c++/101387
gcc/cp/ChangeLog:
PR c++/101387
* tree.c (cp_build_qualified_type_real): Excluding typedef from error
gcc/testsuite/ChangeLog:
PR c++/101387
* g++.dg/parse/pr101783.C: New test.
diff --git gcc/cp/tree.c gcc/cp/tree.c
index 10b818d1370..a4ae3eee6d0 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -1361,11 +1361,18 @@ cp_build_qualified_type_real (tree type,
/* A reference or method type shall not be cv-qualified.
[dcl.ref], [dcl.fct]. This used to be an error, but as of DR 295
(in CD1) we always ignore extra cv-quals on functions. */
+ /* Cv-qualified references are ill-formed except when the cv-qualifiers
+ are introduced through the use of a typedef-name ([dcl.typedef],
+ [temp.param]) or decltype-specifier ([dcl.type.decltype]),
+ in which case the cv-qualifiers are ignored. */
if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
&& (TYPE_REF_P (type)
|| FUNC_OR_METHOD_TYPE_P (type)))
{
- if (TYPE_REF_P (type))
+ if (TYPE_REF_P (type)
+ //A reference from typedef is not an error, but ignored.
+ && (!typedef_variant_p (type) || FUNC_OR_METHOD_TYPE_P (type)))
bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
}
diff --git gcc/testsuite/g++.dg/parse/pr101783.C gcc/testsuite/g++.dg/parse/pr101783.C
new file mode 100644
index 00000000000..8f8f8b1faeb
--- /dev/null
+++ gcc/testsuite/g++.dg/parse/pr101783.C
@@ -0,0 +1,10 @@
+template<class T> struct A{
+ typedef T& Type;
+};
+template<class T>
+void f(const typename A<T>::Type){}
+template<>
+void f<int>(const typename A<int>::Type){}
+struct B{};
+template<>
+void f<B>(const A<B>::Type){}
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: Fix unnecessary error when top-level cv-qualifiers is dropped [PR101783]
2021-08-10 5:36 [PATCH] c++: Fix unnecessary error when top-level cv-qualifiers is dropped [PR101783] nick huang
@ 2021-08-24 15:29 ` Jonathan Wakely
2021-08-28 11:54 ` [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] nick huang
1 sibling, 0 replies; 5+ messages in thread
From: Jonathan Wakely @ 2021-08-24 15:29 UTC (permalink / raw)
To: nickhuang99; +Cc: gcc-patches
>PR c++/101387
>
>gcc/cp/ChangeLog:
> PR c++/101387
> * tree.c (cp_build_qualified_type_real): Excluding typedef from error
>
>gcc/testsuite/ChangeLog:
> PR c++/101387
> * g++.dg/parse/pr101783.C: New test.
This is the wrong PR number.
How has this ptch been tested? Have you bootstrapped the compiler and
run the full testsuite?
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783]
2021-08-10 5:36 [PATCH] c++: Fix unnecessary error when top-level cv-qualifiers is dropped [PR101783] nick huang
2021-08-24 15:29 ` Jonathan Wakely
@ 2021-08-28 11:54 ` nick huang
2021-09-24 11:15 ` *PING* " nick huang
2021-09-24 20:33 ` Jason Merrill
1 sibling, 2 replies; 5+ messages in thread
From: nick huang @ 2021-08-28 11:54 UTC (permalink / raw)
To: gcc-patches
Reference with cv-qualifiers should be ignored instead of causing an error
because standard accepts cv-qualified references introduced by typedef which
is ignored.
Therefore, the fix prevents GCC from reporting error by not setting variable
"bad_quals" in case the reference is introduced by typedef. Still the
cv-qualifier is silently ignored.
Here I quote spec (https://timsong-cpp.github.io/cppwp/dcl.ref#1):
"Cv-qualified references are ill-formed except when the cv-qualifiers
are introduced through the use of a typedef-name ([dcl.typedef],
[temp.param]) or decltype-specifier ([dcl.type.decltype]),
in which case the cv-qualifiers are ignored."
PR c++/101783
gcc/cp/ChangeLog:
2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
* tree.c (cp_build_qualified_type_real):
gcc/testsuite/ChangeLog:
2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
* g++.dg/parse/pr101783.C: New test.
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 8840932dba2..7aa4318a574 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -1356,12 +1356,22 @@ cp_build_qualified_type_real (tree type,
/* A reference or method type shall not be cv-qualified.
[dcl.ref], [dcl.fct]. This used to be an error, but as of DR 295
(in CD1) we always ignore extra cv-quals on functions. */
+
+ /* PR 101783
+ Cv-qualified references are ill-formed except when the cv-qualifiers
+ are introduced through the use of a typedef-name ([dcl.typedef],
+ [temp.param]) or decltype-specifier ([dcl.type.decltype]),
+ in which case the cv-qualifiers are ignored.
+ */
if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
&& (TYPE_REF_P (type)
|| FUNC_OR_METHOD_TYPE_P (type)))
{
- if (TYPE_REF_P (type))
+ // do NOT set bad_quals when non-method reference is introduced by typedef.
+ if (TYPE_REF_P (type)
+ && (!typedef_variant_p (type) || FUNC_OR_METHOD_TYPE_P (type)))
bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
+ // non-method reference introduced by typedef is also dropped silently
type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
}
diff --git a/gcc/testsuite/g++.dg/parse/pr101783.C b/gcc/testsuite/g++.dg/parse/pr101783.C
new file mode 100644
index 00000000000..4e0a435dd0b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/pr101783.C
@@ -0,0 +1,5 @@
+template<class T> struct A{
+ typedef T& Type;
+};
+template<class T> void f(const typename A<T>::Type){}
+template <> void f<int>(const typename A<int>::Type){}
^ permalink raw reply [flat|nested] 5+ messages in thread
* *PING* Re: [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783]
2021-08-28 11:54 ` [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] nick huang
@ 2021-09-24 11:15 ` nick huang
2021-09-24 20:33 ` Jason Merrill
1 sibling, 0 replies; 5+ messages in thread
From: nick huang @ 2021-09-24 11:15 UTC (permalink / raw)
To: gcc-patches
Reference with cv-qualifiers should be ignored instead of causing an error
because standard accepts cv-qualified references introduced by typedef which
is ignored.
Therefore, the fix prevents GCC from reporting error by not setting variable
"bad_quals" in case the reference is introduced by typedef. Still the
cv-qualifier is silently ignored.
Here I quote spec (https://timsong-cpp.github.io/cppwp/dcl.ref#1):
"Cv-qualified references are ill-formed except when the cv-qualifiers
are introduced through the use of a typedef-name ([dcl.typedef],
[temp.param]) or decltype-specifier ([dcl.type.decltype]),
in which case the cv-qualifiers are ignored."
PR c++/101783
gcc/cp/ChangeLog:
2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
* tree.c (cp_build_qualified_type_real):
gcc/testsuite/ChangeLog:
2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
* g++.dg/parse/pr101783.C: New test.
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 8840932dba2..7aa4318a574 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -1356,12 +1356,22 @@ cp_build_qualified_type_real (tree type,
/* A reference or method type shall not be cv-qualified.
[dcl.ref], [dcl.fct]. This used to be an error, but as of DR 295
(in CD1) we always ignore extra cv-quals on functions. */
+
+ /* PR 101783
+ Cv-qualified references are ill-formed except when the cv-qualifiers
+ are introduced through the use of a typedef-name ([dcl.typedef],
+ [temp.param]) or decltype-specifier ([dcl.type.decltype]),
+ in which case the cv-qualifiers are ignored.
+ */
if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
&& (TYPE_REF_P (type)
|| FUNC_OR_METHOD_TYPE_P (type)))
{
- if (TYPE_REF_P (type))
+ // do NOT set bad_quals when non-method reference is introduced by typedef.
+ if (TYPE_REF_P (type)
+ && (!typedef_variant_p (type) || FUNC_OR_METHOD_TYPE_P (type)))
bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
+ // non-method reference introduced by typedef is also dropped silently
type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
}
diff --git a/gcc/testsuite/g++.dg/parse/pr101783.C b/gcc/testsuite/g++.dg/parse/pr101783.C
new file mode 100644
index 00000000000..4e0a435dd0b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/pr101783.C
@@ -0,0 +1,5 @@
+template<class T> struct A{
+ typedef T& Type;
+};
+template<class T> void f(const typename A<T>::Type){}
+template <> void f<int>(const typename A<int>::Type){}
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783]
2021-08-28 11:54 ` [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] nick huang
2021-09-24 11:15 ` *PING* " nick huang
@ 2021-09-24 20:33 ` Jason Merrill
1 sibling, 0 replies; 5+ messages in thread
From: Jason Merrill @ 2021-09-24 20:33 UTC (permalink / raw)
To: nick huang, gcc-patches
On 8/28/21 07:54, nick huang via Gcc-patches wrote:
> Reference with cv-qualifiers should be ignored instead of causing an error
> because standard accepts cv-qualified references introduced by typedef which
> is ignored.
> Therefore, the fix prevents GCC from reporting error by not setting variable
> "bad_quals" in case the reference is introduced by typedef. Still the
> cv-qualifier is silently ignored.
> Here I quote spec (https://timsong-cpp.github.io/cppwp/dcl.ref#1):
> "Cv-qualified references are ill-formed except when the cv-qualifiers
> are introduced through the use of a typedef-name ([dcl.typedef],
> [temp.param]) or decltype-specifier ([dcl.type.decltype]),
> in which case the cv-qualifiers are ignored."
>
> PR c++/101783
>
> gcc/cp/ChangeLog:
>
> 2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
>
> * tree.c (cp_build_qualified_type_real):
The git commit verifier rejects this commit message with
Checking 1fa0fbcdd15adf936ab4fae584f841beb35da1bb: FAILED ERR: missing
description of a change:
" * tree.c (cp_build_qualified_type_real):"
(your initial patch had a description here, you just need to copy it over)
ERR: PR 101783 in subject but not in changelog:
"c++: Suppress error when cv-qualified reference is introduced by
typedef [PR101783]"
(the PR number needs to have a Tab before it)
In Jonathan's earlier reply he asked how you tested the patch; this
message still doesn't say anything about that.
https://gcc.gnu.org/contribute.html#testing
What is the legal status of your contributions?
https://gcc.gnu.org/contribute.html#legal
Existing code tries to handle this with the tf_ignore_bad_quals, but the
unnecessary use of typename gets past the code that tries to set the
flag. But your approach is nice and straightforward, so let's go ahead
with it.
> gcc/testsuite/ChangeLog:
>
> 2021-08-27 qingzhe huang <nickhuang99@hotmail.com>
>
> * g++.dg/parse/pr101783.C: New test.
>
> diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
> index 8840932dba2..7aa4318a574 100644
> --- a/gcc/cp/tree.c
> +++ b/gcc/cp/tree.c
> @@ -1356,12 +1356,22 @@ cp_build_qualified_type_real (tree type,
> /* A reference or method type shall not be cv-qualified.
> [dcl.ref], [dcl.fct]. This used to be an error, but as of DR 295
> (in CD1) we always ignore extra cv-quals on functions. */
> +
> + /* PR 101783
Let's cite where this comes from in the standard ([dcl.ref]/1), and not
the PR number.
> + Cv-qualified references are ill-formed except when the cv-qualifiers
> + are introduced through the use of a typedef-name ([dcl.typedef],
> + [temp.param]) or decltype-specifier ([dcl.type.decltype]),
> + in which case the cv-qualifiers are ignored.
> + */
> if (type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)
> && (TYPE_REF_P (type)
> || FUNC_OR_METHOD_TYPE_P (type)))
> {
> - if (TYPE_REF_P (type))
> + // do NOT set bad_quals when non-method reference is introduced by typedef.
> + if (TYPE_REF_P (type)
> + && (!typedef_variant_p (type) || FUNC_OR_METHOD_TYPE_P (type)))
> bad_quals |= type_quals & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
> + // non-method reference introduced by typedef is also dropped silently
These two // comments seem redundant with the quote from the standard
above, let's drop them.
> type_quals &= ~(TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE);
> }
>
> diff --git a/gcc/testsuite/g++.dg/parse/pr101783.C b/gcc/testsuite/g++.dg/parse/pr101783.C
> new file mode 100644
> index 00000000000..4e0a435dd0b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/parse/pr101783.C
> @@ -0,0 +1,5 @@
> +template<class T> struct A{
> + typedef T& Type;
> +};
> +template<class T> void f(const typename A<T>::Type){}
> +template <> void f<int>(const typename A<int>::Type){}
>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-09-24 20:33 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-08-10 5:36 [PATCH] c++: Fix unnecessary error when top-level cv-qualifiers is dropped [PR101783] nick huang
2021-08-24 15:29 ` Jonathan Wakely
2021-08-28 11:54 ` [PATCH] c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] nick huang
2021-09-24 11:15 ` *PING* " nick huang
2021-09-24 20:33 ` Jason Merrill
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