This is not required by the standard (yet), but there seems to be reasonable
support for this being a defect according to CWG discussion, and libstdc++ 7.1
relies on it working.
llvm-svn: 304946
such guides below explicit ones, and ensure that references to the class's
template parameters are not treated as forwarding references.
We make a few tweaks to the wording in the current standard:
1) The constructor parameter list is copied faithfully to the deduction guide,
without losing default arguments or a varargs ellipsis (which the standard
wording loses by omission).
2) If the class template declares no constructors, we add a T() -> T<...> guide
(which will only ever work if T has default arguments for all non-pack
template parameters).
3) If the class template declares nothing that looks like a copy or move
constructor, we add a T(T<...>) -> T<...> guide.
#2 and #3 follow from the "pretend we had a class type with these constructors"
philosophy for deduction guides.
llvm-svn: 295007
We model deduction-guides as functions with a new kind of name that identifies
the template whose deduction they guide; the bulk of this patch is adding the
new name kind. This gives us a clean way to attach an extensible list of guides
to a class template in a way that doesn't require any special handling in AST
files etc (and we're going to need these functions we come to performing
deduction).
llvm-svn: 294266
name. If the dependent name happened to end in a template-id (X<T>::Y<U>), we
would fail to notice that the 'typename' keyword is missing when resolving it
to a type.
It turns out that GCC has a similar bug. If this shows up in much real code, we
can easily downgrade this to an ExtWarn.
llvm-svn: 293815
This rule permits the injected-class-name of a class template to be used as
both a template type argument and a template template argument, with no extra
syntax required to disambiguate.
llvm-svn: 292426
This issue clarifies how deduction proceeds past a non-trailing function
parameter pack. Essentially, the pack itself is skipped and consumes no
arguments (except for those implied by an explicitly-specified template
arguments), and nothing is deduced from it. As a small fix to the standard's
rule, we do not allow subsequent deduction to change the length of the function
parameter pack (by preventing extension of the explicitly-specified pack if
present, and otherwise deducing all contained packs to empty packs).
llvm-svn: 291425
This implements something like the current direction of DR1581: we use a narrow
syntactic check to determine the set of places where a constant expression
could be evaluated, and only instantiate a constexpr function or variable if
it's referenced in one of those contexts, or is odr-used.
It's not yet clear whether this is the right set of syntactic locations; we
currently consider all contexts within templates that would result in odr-uses
after instantiation, and contexts within list-initialization (narrowing
conversions take another victim...), as requiring instantiation. We could in
principle restrict the former cases more (only const integral / reference
variable initializers, and contexts in which a constant expression is required,
perhaps). However, this is sufficient to allow us to accept libstdc++ code,
which relies on GCC's behavior (which appears to be somewhat similar to this
approach).
llvm-svn: 291318
to make reference to template parameters. This is only a partial
implementation; we retain the restriction that the argument must not be
type-dependent, since it's unclear how that would work given the existence of
other language rules requiring an exact type match in this context, even for
type-dependent cases (a question has been raised on the core reflector).
llvm-svn: 290647
specialized than the primary template. (Put another way, if we imagine there
were a partial specialization matching the primary template, we should never
select it if some other partial specialization also matches.)
llvm-svn: 290593
template arguments as written rather than the canonical template arguments,
so we print more user-friendly names for template parameters.
llvm-svn: 290483
fail the merge if the arguments have different types (except if one of them was
deduced from an array bound, in which case take the type from the other).
This is correct because (except in the array bound case) the type of the
template argument in each deduction must match the type of the parameter, so at
least one of the two deduced arguments must have a mismatched type.
This is necessary because we would otherwise lose the type information for the
discarded template argument in the merge, and fail to diagnose the mismatch.
In order to power this, we now properly retain the type of a deduced non-type
template argument deduced from a declaration, rather than giving it the type of
the template parameter; we'll convert it to the template parameter type when
checking the deduced arguments.
llvm-svn: 290399
Much to my surprise, '-disable-llvm-optzns' which I thought was the
magical flag I wanted to get at the raw LLVM IR coming out of Clang
deosn't do that. It still runs some passes over the IR. I don't want
that, I really want the *raw* IR coming out of Clang and I strongly
suspect everyone else using it is in the same camp.
There is actually a flag that does what I want that I didn't know about
called '-disable-llvm-passes'. I suspect many others don't know about it
either. It both does what I want and is much simpler.
This removes the confusing version and makes that spelling of the flag
an alias for '-disable-llvm-passes'. I've also moved everything in Clang
to use the 'passes' spelling as it seems both more accurate (*all* LLVM
passes are disabled, not just optimizations) and much easier to remember
and spell correctly.
This is part of simplifying how Clang drives LLVM to make it cleaner to
wire up to the new pass manager.
Differential Revision: https://reviews.llvm.org/D28047
llvm-svn: 290392
Other compilers accept invalid code here that we reject, and we need a
better error message to try to convince users that the code is really
incorrect. Consider:
class Foo {
typedef MyIterHelper<Foo> iterator;
friend class iterator;
};
Previously our wording was "elaborated type refers to a typedef".
"elaborated type" isn't widely known terminology, so the new diagnostic
says "typedef 'iterator' cannot be referenced with class specifier".
Reviewers: rsmith
Differential Revision: https://reviews.llvm.org/D25216
llvm-svn: 289259
mismatched dynamic exception specifications in expressions from an error to a
warning, since this is no longer ill-formed in C++1z.
Allow reference binding of a reference-to-non-noexcept function to a noexcept
function lvalue. As defect resolutions, also allow a conditional between
noexcept and non-noexcept function lvalues to produce a non-noexcept function
lvalue (rather than decaying to a function pointer), and allow function
template argument deduction to deduce a reference to non-noexcept function when
binding to a noexcept function type.
llvm-svn: 284905
explicit specialization to a warning for C++98 mode (this is a defect report
resolution, so per our informal policy it should apply in C++98), and turn
the warning on by default for C++11 and later. In all cases where it fires, the
right thing to do is to remove the pointless explicit instantiation.
llvm-svn: 280308
they're redeclarations. This is necessary in order for name lookup to correctly
find the most recent declaration of the name (which affects default template
argument lookup and cross-module merging, among other things).
llvm-svn: 275612
The problem is that the parameter pack in a function type type alias is not
reexpanded after being transformed. Also remove an incorrect comment in a
similar function. Fixes PR26017.
Differential Revision: http://reviews.llvm.org/D21030
llvm-svn: 274566
Crash reported in PR28023 is caused by the fact that non-type template
parameters are found by tag name lookup. In the code provided in that PR:
template<int V> struct A {
struct B {
template <int> friend struct V;
};
};
the template parameter V is found when lookup for redeclarations of 'struct V'
is made. Latter on the error about shadowing of 'V' is emitted but the semantic
context of 'struct V' is already determined wrong: 'struct A' instead of
translation unit.
The fix moves the check for shadowing toward the beginning of the method and
thus prevents from wrong context calculations.
This change fixes PR28023.
llvm-svn: 272366
if we are parsing a template specialization.
This commit makes changes to clear the TemplateParamScope bit and set
the TemplateParamParent field of the current scope to null if a template
specialization is being parsed.
Before this commit, Sema::ActOnStartOfLambdaDefinition would check
whether the parent template scope had any decls to determine whether
or not a template specialization was being parsed. This wasn't correct
since it couldn't distinguish between a real template specialization and
a template defintion with an unnamed template parameter (only template
parameters with names are added to the scope's decl list). To fix the
bug, this commit changes the code to check the pointer to the parent
template scope rather than the decl list.
rdar://problem/23440346
Differential Revision: http://reviews.llvm.org/D19175
llvm-svn: 267975
With this patch compiler emits warning if it tries to make implicit instantiation
of a template but cannot find the template definition. The warning can be suppressed
by explicit instantiation declaration or by command line options
-Wundefined-var-template and -Wundefined-func-template. The implementation follows
the discussion of http://reviews.llvm.org/D12326.
Differential Revision: http://reviews.llvm.org/D16396
llvm-svn: 266719
into IDNS_Tag in C++, because they conflict with redeclarations of tags. (This
doesn't affect elaborated-type-specifier lookup, which looks for IDNS_Type in
C++).
llvm-svn: 256985
by overload resolution because deduction succeeds, but the substituted
parameter type for some parameter (with deduced type) doesn't exactly match the
corresponding adjusted argument type.
llvm-svn: 256657
do scope-based lookup when looking for redeclarations of them. Add some related
missing checks for the scope-based redeclaration lookup: properly filter the
list of found declarations to match the scope, and diagnose shadowing of a
template parameter name.
llvm-svn: 254663
This patch emits a more appropriate (but still noisy) diagnostic stream when a lambda-expression is encountered within a non-type default argument.
For e.g. template<int N = ([] { return 5; }())> int f();
As opposed to complaining that a lambda expression is not allowed in an unevaluated operand, the patch complains about the lambda being forbidden in a constant expression context (which will be allowed in C++17 now that they have been accepted by EWG, unless of course CWG or national bodies (that have so far shown no signs of concern) rise in protest)
As I start submitting patches for constexpr lambdas (http://wg21.link/P0170R0) under C++1z (OK'd by Richard Smith at Kona), this will be one less change to make.
Thanks!
llvm-svn: 253431
Richard Smith