[clang] disallow narrowing when matching template template parameters (#124313)

This fixes the core issue described in P3579, following the design
intent of P0522 to not introduce any new cases whe

[clang] disallow narrowing when matching template template parameters (#124313)

This fixes the core issue described in P3579, following the design
intent of P0522 to not introduce any new cases where a template template
parameter match is allowed for a template which is not valid for all
possible uses.

With this patch, narrowing conversions are disallowed for TTP matching.

This reuses the existing machinery for diagnosing narrowing in a
converted constant expression.
Since P0522 is a DR and we apply it all the way back to C++98, this
brings that machinery to use in older standards, in this very narrow
scope of TTP matching.

This still doesn't solve the ambiguity when partial ordering NTTPs of
different integral types, this is blocked by a different bug which will
be fixed in a subsequent patch (but the test cases are added).

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Template Diagnostic Improvements (#99933)

It turns out `SemaTemplate` handles this type of diagnostic already,
however when template gets encountered, it never gets parsed as a
possible statement

Template Diagnostic Improvements (#99933)

It turns out `SemaTemplate` handles this type of diagnostic already,
however when template gets encountered, it never gets parsed as a
possible statement or declaration, only as an expression.

Fixes #17959.

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[Clang][Sema] Diagnose variable template explicit specializations with storage-class-specifiers (#93873)

According to [temp.expl.spec] p2:
> The declaration in an _explicit-specialization_ shall no

[Clang][Sema] Diagnose variable template explicit specializations with storage-class-specifiers (#93873)

According to [temp.expl.spec] p2:
> The declaration in an _explicit-specialization_ shall not be an
_export-declaration_. An explicit specialization shall not use a
_storage-class-specifier_ other than `thread_local`.

Clang partially implements this, but a number of issues exist:
1. We don't diagnose class scope explicit specializations of variable
templates with _storage-class-specifiers_, e.g.
```
struct A
{
template<typename T>
static constexpr int x = 0;

template<>
static constexpr int x<void> = 1; // ill-formed, but clang accepts
};
````
2. We incorrectly reject class scope explicit specializations of
variable templates when `static` is not used, e.g.
```
struct A
{
template<typename T>
static constexpr int x = 0;

template<>
constexpr int x<void> = 1; // error: non-static data member cannot be
constexpr; did you intend to make it static?
};
````
3. We don't diagnose dependent class scope explicit specializations of
function templates with storage class specifiers, e.g.
```
template<typename T>
struct A
{
template<typename U>
static void f();

template<>
static void f<int>(); // ill-formed, but clang accepts
};
````

This patch addresses these issues as follows:
- # 1 is fixed by issuing a diagnostic when an explicit
specialization of a variable template has storage class specifier
- # 2 is fixed by considering any non-function declaration with any
template parameter lists at class scope to be a static data member. This
also allows for better error recovery (it's more likely the user
intended to declare a variable template than a "field template").
- # 3 is fixed by checking whether a function template explicit
specialization has a storage class specifier even when the primary
template is not yet known.

One thing to note is that it would be far simpler to diagnose this when
parsing the _decl-specifier-seq_, but such an implementation would
necessitate a refactor of `ParsedTemplateInfo` which I believe to be
outside the scope of this patch.

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[clang] Enable C++17 relaxed template template argument matching by default (#89807)

This patch will finally allow us to mark C++17 support in clang as
complete.

In order to implement this a

[clang] Enable C++17 relaxed template template argument matching by default (#89807)

This patch will finally allow us to mark C++17 support in clang as
complete.

In order to implement this as a DR and avoid breaking reasonable code
that worked before P0522, this patch implements a provisional resolution
for CWG2398: When deducing template template parameters against each other,
and the argument side names a template specialization, instead of just
deducing A, we deduce a synthesized template template parameter based
on A, but with it's parameters using the template specialization's arguments
as defaults.

The driver flag is deprecated with a warning.

Fixes https://github.com/llvm/llvm-project/issues/36505

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Revert "[clang] deprecate frelaxed-template-template-args, make it on by default"

This reverts commit 2d7fba5f95f0614f6f2c4a4ed966b307d617898b.

The patch was reverted because it caused regression w

Revert "[clang] deprecate frelaxed-template-template-args, make it on by default"

This reverts commit 2d7fba5f95f0614f6f2c4a4ed966b307d617898b.

The patch was reverted because it caused regression with rocThrust
due to ambiguity of template specialization.

For details please see https://reviews.llvm.org/D109496

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[clang] deprecate frelaxed-template-template-args, make it on by default

A resolution to the ambiguity issues created by P0522, which is a DR solving
CWG 150, did not come as expected, so we are jus

[clang] deprecate frelaxed-template-template-args, make it on by default

A resolution to the ambiguity issues created by P0522, which is a DR solving
CWG 150, did not come as expected, so we are just going to accept the change,
and watch how users digest it.

For now we deprecate the flag with a warning, and make it on by default.
We don't remove the flag completely in order to give users a chance to
work around any problems by disabling it.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D109496

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Fix a couple of places where we assumed that non-type template parameters are always rvalues.

llvm-svn: 325095

Add test.

llvm-svn: 184465

Don't try to check override control for invalid member functions. Fixes a crash in a corner case. Patch by Olivier Goffart!

llvm-svn: 163337

When we see an out-of-line definition of a member class template that
does not match any declaration in the class (or class template), be
sure to mark it as invalid. Fixes PR10924 / <rdar://problem/1

When we see an out-of-line definition of a member class template that
does not match any declaration in the class (or class template), be
sure to mark it as invalid. Fixes PR10924 / <rdar://problem/10119422>.

llvm-svn: 143504

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Diagnose attempts to write a templated data member, from Stepan
Dyatkovskiy! Fixes PR10896.

llvm-svn: 140250

Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead o

Update tests to use %clang_cc1 instead of 'clang-cc' or 'clang -cc1'.
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).

llvm-svn: 91446

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Before checking a template template argument against its corresponding
template template parameter, substitute any prior template arguments
into the template template parameter. This, for example, al

Before checking a template template argument against its corresponding
template template parameter, substitute any prior template arguments
into the template template parameter. This, for example, allows us to
properly check the template template argument for a class such as:

template<typename T, template<T Value> class X> struct Foo;

The actual implementation of this feature was trivial; most of the
change is dedicated to giving decent diagnostics when this
substitution goes horribly wrong. We now get a note like:

note: while substituting prior template arguments into template
template parameter 'X' [with T = float]

As part of this change, enabled some very pedantic checking when
comparing template template parameter lists, which shook out a bug in
our overly-eager checking of default arguments of template template
parameters. We now perform only minimal checking of such default
arguments when they are initially parsed.

llvm-svn: 86864

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Instantiation of template template parameters for nested templates, e.g.,

template<typename T>
struct X {
template<template<T Value> class Y> struct Inner;
};

llvm-svn: 86844

Implement template instantiation for non-type template
parameters. Fixes PR5103.

llvm-svn: 84979

When re-entering a template scope, we may be entering a class template
partial specialization rather than a subclass of TemplateDecl. Fixes a
crash in libstdc++ 4.2's <map>.

llvm-svn: 81407

Improve diagnostics and recovery when the nested-name-specifier of a
qualified name does not actually refer into a class/class
template/class template partial specialization.

Improve printing of ne

Improve diagnostics and recovery when the nested-name-specifier of a
qualified name does not actually refer into a class/class
template/class template partial specialization.

Improve printing of nested-name-specifiers to eliminate redudant
qualifiers. Also, make it possible to output a nested-name-specifier
through a DiagnosticBuilder, although there are relatively few places
that will use this leeway.

llvm-svn: 80056

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Test out-of-line definition of a static data member of a member class of a nested class template. Phew

llvm-svn: 80046

Test out-of-line definitions of static data members of nested member class templates

llvm-svn: 80045

Improve support for out-of-line definitions of nested templates and
their members, including member class template, member function
templates, and member classes and functions of member templates.

T

Improve support for out-of-line definitions of nested templates and
their members, including member class template, member function
templates, and member classes and functions of member templates.

To actually parse the nested-name-specifiers that qualify the name of
an out-of-line definition of a member template, e.g.,

template<typename X> template<typename Y>
X Outer<X>::Inner1<Y>::foo(Y) {
return X();
}

we need to look for the template names (e.g., "Inner1") as a member of
the current instantiation (Outer<X>), even before we have entered the
scope of the current instantiation. Since we can't do this in general
(i.e., we should not be looking into all dependent
nested-name-specifiers as if they were the current instantiation), we
rely on the parser to tell us when it is parsing a declaration
specifier sequence, and, therefore, when we should consider the
current scope specifier to be a current instantiation.

Printing of complicated, dependent nested-name-specifiers may be
somewhat broken by this commit; I'll add tests for this issue and fix
the problem (if it still exists) in a subsequent commit.

llvm-svn: 80044

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Implement out-of-line definitions of nested class templates. Most of
the logic is there for out-of-line definitions with multiple levels of
nested templates, but this is still a work-in-progress: we'

Implement out-of-line definitions of nested class templates. Most of
the logic is there for out-of-line definitions with multiple levels of
nested templates, but this is still a work-in-progress: we're having
trouble determining when we should look into a dependent
nested-name-specifier.

llvm-svn: 80003

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Keep track of the template parameter depth properly when we have
member templates declared inside other templates. This allows us to
match out-of-line definitions of member function templates within

Keep track of the template parameter depth properly when we have
member templates declared inside other templates. This allows us to
match out-of-line definitions of member function templates within
class templates to the declarations within the class template. We
still can't handle out-of-line definitions for member class templates,
however.

llvm-svn: 79955

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Diagnose class members that shadow a template parameter. Fixes
<rdar://problem/6952203>.

To do this, we actually remove a not-quite-correct optimization in the
C++ name lookup routines. We'll revis

Diagnose class members that shadow a template parameter. Fixes
<rdar://problem/6952203>.

To do this, we actually remove a not-quite-correct optimization in the
C++ name lookup routines. We'll revisit this optimization for the
general case once more C++ is working.

llvm-svn: 73659

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Tests and fixes for templates declared within (non-template)
classes. Test case from Anders Carlsson, fix from Piotr Rak!

llvm-svn: 67817