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] Remove rdar links; NFC

We have a new policy in place making links to private resources
something we try to avoid in source and test files. Normally, we'd
organically switch to the new policy

[clang] Remove rdar links; NFC

We have a new policy in place making links to private resources
something we try to avoid in source and test files. Normally, we'd
organically switch to the new policy rather than make a sweeping change
across a project. However, Clang is in a somewhat special circumstance
currently: recently, I've had several new contributors run into rdar
links around test code which their patch was changing the behavior of.
This turns out to be a surprisingly bad experience, especially for
newer folks, for a handful of reasons: not understanding what the link
is and feeling intimidated by it, wondering whether their changes are
actually breaking something important to a downstream in some way,
having to hunt down strangers not involved with the patch to impose on
them for help, accidental pressure from asking for potentially private
IP to be made public, etc. Because folks run into these links entirely
by chance (through fixing bugs or working on new features), there's not
really a set of problematic links to focus on -- all of the links have
basically the same potential for causing these problems. As a result,
this is an omnibus patch to remove all such links.

This was not a mechanical change; it was done by manually searching for
rdar, radar, radr, and other variants to find all the various
problematic links. From there, I tried to retain or reword the
surrounding comments so that we would lose as little context as
possible. However, because most links were just a plain link with no
supporting context, the majority of the changes are simple removals.

Differential Review: https://reviews.llvm.org/D158071

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Revert "Remove rdar links; NFC"

This reverts commit d618f1c3b12effd0c2bdb7d02108d3551f389d3d.
This commit wasn't reviewed ahead of time and significant concerns were
raised immediately after it land

Revert "Remove rdar links; NFC"

This reverts commit d618f1c3b12effd0c2bdb7d02108d3551f389d3d.
This commit wasn't reviewed ahead of time and significant concerns were
raised immediately after it landed. According to our developer policy
this warrants immediate revert of the commit.

https://llvm.org/docs/DeveloperPolicy.html#patch-reversion-policy

Differential Revision: https://reviews.llvm.org/D155509

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Remove rdar links; NFC

This removes links to rdar, which is an internal bug tracker that the
community doesn't have visibility into.

See further discussion at:
https://discourse.llvm.org/t/code-rev

Remove rdar links; NFC

This removes links to rdar, which is an internal bug tracker that the
community doesn't have visibility into.

See further discussion at:
https://discourse.llvm.org/t/code-review-reminder-about-links-in-code-commit-messages/71847

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[test] Make tests pass regardless of gnu++14/gnu++17 default

GCC from 11 onwards defaults to -std=gnu++17 for C++ source files. We want to do the same
(https://discourse.llvm.org/t/c-objc-switch-to-

[test] Make tests pass regardless of gnu++14/gnu++17 default

GCC from 11 onwards defaults to -std=gnu++17 for C++ source files. We want to do the same
(https://discourse.llvm.org/t/c-objc-switch-to-gnu-17-as-the-default-dialect/64360).
Split RUN lines, adjust `-verify`, or add `__cplusplus < 201703L` or `-Wno-dynamic-exception-spec`,
so that tests will pass regardless of gnu++14/gnu++17 default.

We have a desire to mark a test compatible with multiple language standards.
There are ongoing discussions how to add markers in the long term:

* https://discourse.llvm.org/t/iterating-lit-run-lines/62596
* https://discourse.llvm.org/t/lit-run-a-run-line-multiple-times-with-different-replacements/64932

As a workaround in the short term, add lit substitutions `%std_cxx98-`,
`%std_cxx11-14`, etc. They can be used for tests which work across multiple
language standards. If a range has `n` standards, run lit multiple times, with
`LIT_CLANG_STD_GROUP=0`, `LIT_CLANG_STD_GROUP=1`, etc to cover all `n` standards.

Reviewed By: #clang-language-wg, aaron.ballman

Differential Revision: https://reviews.llvm.org/D131464

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Change the behavior of implicit int diagnostics

C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 w

Change the behavior of implicit int diagnostics

C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 without a deprecation period, so implementations continued to
support the feature. Now, as with implicit function declarations, is a
good time to reevaluate the need for this support.

This patch allows -Wimplicit-int to issue warnings in C89 mode (off by
default), defaults the warning to an error in C99 through C17, and
disables support for the feature entirely in C2x. It also removes a
warning about missing declaration specifiers that really was just an
implicit int warning in disguise and other minor related cleanups.

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Update the message for template-template param keyword for C++17

C++17 permits using 'typename' or 'class' for a template template
parameter, but the error message in the parser only refers to 'clas

Update the message for template-template param keyword for C++17

C++17 permits using 'typename' or 'class' for a template template
parameter, but the error message in the parser only refers to 'class'.
This patch, in C++17 or newer modes, adds "or 'template'" to the
diagnostic.

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PR46231: Promote diagnostic for 'template<...>;' from ExtWarn to Error.

No other compiler accepts this as an extension, not even in permissive
mode. We're not doing anyone any favors by allowing thi

PR46231: Promote diagnostic for 'template<...>;' from ExtWarn to Error.

No other compiler accepts this as an extension, not even in permissive
mode. We're not doing anyone any favors by allowing this, and it's
unlikely to be at all common, even in Clang-only code, in the wild.

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[clang] Include type specifiers in typo correction when checking isCXXDeclarationSpecifiers.

- add more tests (the test added in https://github.com/llvm/llvm-project/commit/2f448467e4254ddc3191136c9

[clang] Include type specifiers in typo correction when checking isCXXDeclarationSpecifiers.

- add more tests (the test added in https://github.com/llvm/llvm-project/commit/2f448467e4254ddc3191136c968e6054bc009b88 is weak);
- improve the `MyTemplate<type_typo, int>();` case, with this patch, typo correction
suggests the type decl, and no regressions found.

Differential Revision: https://reviews.llvm.org/D83025

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[clang] Fix a null-NSS-access crash in DependentNameType.

The DependentNameType must have a non-null NSS. This property could be
violated during typo correction.

Differential Revision: https://revi

[clang] Fix a null-NSS-access crash in DependentNameType.

The DependentNameType must have a non-null NSS. This property could be
violated during typo correction.

Differential Revision: https://reviews.llvm.org/D82738

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PR45239: Don't deallocate TemplateIdAnnotations if they might still be
in the token stream.

Previously we deleted all template-id annotations at the end of each
top-level declaration. That doesn't w

PR45239: Don't deallocate TemplateIdAnnotations if they might still be
in the token stream.

Previously we deleted all template-id annotations at the end of each
top-level declaration. That doesn't work: we can do some lookahead and
form a template-id annotation, and then roll back that lookahead, parse,
and decide that we're missing a semicolon at the end of a top-level
declaration, before we reach the annotation token. In that situation,
we'd end up parsing the annotation token after deleting its associated
data, leading to various forms of badness.

We now only delete template-id annotations if the preprocessor can
assure us that there are no annotation tokens left in the token stream
(or if we're already at EOF). This lets us delete the annotation tokens
earlier in a lot of cases; we now clean them up at the end of each
statement and class member, not just after each top-level declaration.
This also permitted some simplification of the delay-parsed templates
cleanup code.

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Improve error recovery from missing '>' in template argument list.

Produce the conventional "to match this '<'" note, so that the user
knows why we expected a '>', and properly handle '>>' in C++11

Improve error recovery from missing '>' in template argument list.

Produce the conventional "to match this '<'" note, so that the user
knows why we expected a '>', and properly handle '>>' in C++11 onwards.

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Improve recovery from invalid template-ids.

Instead of bailing out of parsing when we encounter an invalid
template-name or template arguments in a template-id, produce an
annotation token describin

Improve recovery from invalid template-ids.

Instead of bailing out of parsing when we encounter an invalid
template-name or template arguments in a template-id, produce an
annotation token describing the invalid construct.

This avoids duplicate errors and generally allows us to recover better.
In principle we should be able to extend this to store some kinds of
invalid template-id in the AST for tooling use, but that isn't handled
as part of this change.

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[clang] Fix crash on visiting null nestedNameSpecifier.

Summary: Fix https://github.com/clangd/clangd/issues/293

Reviewers: sammccall

Subscribers: ilya-biryukov, kadircet, usaxena95, cfe-commits

[clang] Fix crash on visiting null nestedNameSpecifier.

Summary: Fix https://github.com/clangd/clangd/issues/293

Reviewers: sammccall

Subscribers: ilya-biryukov, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76320

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PR45063: Fix crash on invalid processing an elaborated class template-id
with an invalid scope specifier.

Fix mishandling of invalid-but-non-empty nested name specifiers in name
classification.

We were accidentally treating invalid scope specs as being empty,
resulting in our trying to form an ADL-only

Fix mishandling of invalid-but-non-empty nested name specifiers in name
classification.

We were accidentally treating invalid scope specs as being empty,
resulting in our trying to form an ADL-only call with a qualified
callee, which tripped up an assert later on.

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PR42071: Reject weird names for non-type template parameters.

Also reject default arguments appearing in invalid locations.

llvm-svn: 363447

[c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose
template name is not visible to unqualified lookup.

In order to support this without a severe degradation in our ability to
di

[c++20] Implement P0846R0: allow (ADL-only) calls to template-ids whose
template name is not visible to unqualified lookup.

In order to support this without a severe degradation in our ability to
diagnose typos in template names, this change significantly restructures
the way we handle template-id-shaped syntax for which lookup of the
template name finds nothing.

Instead of eagerly diagnosing an undeclared template name, we now form a
placeholder template-name representing a name that is known to not find
any templates. When the parser sees such a name, it attempts to
disambiguate whether we have a less-than comparison or a template-id.
Any diagnostics or typo-correction for the name are delayed until its
point of use.

The upshot should be a small improvement of our diagostic quality
overall: we now take more syntactic context into account when trying to
resolve an undeclared identifier on the left hand side of a '<'. In
fact, this works well enough that the backwards-compatible portion (for
an undeclared identifier rather than a lookup that finds functions but
no function templates) is enabled in all language modes.

llvm-svn: 360308

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Diagnose attempts to explicitly instantiate a template at class scope. Previously Clang would simply ignore the 'template' keyword in this case.

llvm-svn: 294639

Diagnose function template definitions inside functions

The parser can only be tricked into parsing a function template
definition by inserting a typename keyword before the function template
declar

Diagnose function template definitions inside functions

The parser can only be tricked into parsing a function template
definition by inserting a typename keyword before the function template
declaration. This used to make us crash, and now it's fixed.

While here, remove an unneeded boolean parameter from ParseDeclGroup.
This boolean always corresponded to non-typedef declarators at file
scope. ParseDeclGroup already has precise diagnostics for the function
definition typedef case, so we can let that through.

Fixes PR21839.

llvm-svn: 224287

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Suggest fix-it for missing '{' after base-clause

llvm-svn: 218468

[C++1z] Implement N4051: 'typename' is permitted instead of 'class' when declaring a template template parameter.

llvm-svn: 211031

Fix PR17637: incorrect calculation of template parameter depth

In delayed template parsing mode, adjust the template depth counter for each template parameter list associated with an out of line mem

Fix PR17637: incorrect calculation of template parameter depth

In delayed template parsing mode, adjust the template depth counter for each template parameter list associated with an out of line member template specialization.

llvm-svn: 196351

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Fix name in test.

llvm-svn: 194291

Fix %select numbering confusion between diagnostic and Diag call.

llvm-svn: 194281