| Message ID | DM5PR0501MB37332890820CC359F119D4D7B5C89@DM5PR0501MB3733.namprd05.prod.outlook.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: Suppress error when cv-qualified reference is introduced by typedef [PR101783] | expand |
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){} > > >
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){}