According to [temp.names] p5:
> The keyword template shall not appear immediately after a declarative nested-name-specifier.
[expr.prim.id.qual] p2 defines a declarative nested-name-specifier as follows:
> A nested-name-specifier is declarative if it is part of
> - a class-head-name,
> - an enum-head-name,
> - a qualified-id that is the id-expression of a declarator-id, or
> - a declarative nested-name-specifier.
Note: I believe this definition is defective as it doesn't include _nested-name-specifiers_ appearing in _elaborated-type-specifiers_ that declare partial/explicit specializations and explicit instantiations. See my post to the core reflector. Minus a few bugs that are addressed by this PR, this is how we implement it.
This means that declarations like:
```
template<typename>
struct A
{
template<typename>
struct B
{
void f();
};
};
template<typename T>
template<typename U>
void A<T>::template B<U>::f() { } // error: 'template' cannot be used after a declarative nested name specifier
```
are ill-formed. This PR add diagnostics for such declarations. The name of the diagnostic group is `template-in-declaration-name`.
Regarding the aforementioned "few bugs that are addressed by this PR" in order to correctly implement this:
- `CheckClassTemplate` did not call `diagnoseQualifiedDeclaration` when the semantic context was dependent. This allowed for constructs like:
```
struct A
{
template<typename T>
struct B
{
template<typename U>
struct C;
};
};
template<typename T>
template<typename U>
struct decltype(A())::B<T>::C { };
```
- `ActOnClassTemplateSpecialization` did not call `diagnoseQualifiedDeclaration` at all, allowing for qualified partial/explicit specializations at class scope and other related nonsense
- `TreeTransform::TransformNestedNameSpecifierLoc` would rebuild a `NestedNameSpecifier::TypeSpecWithTemplate` as a `NestedNameSpecifier::TypeSpec`
- `TemplateSpecializationTypeLoc::initializeLocal` would set the `template` keyword `SourceLocation` to the provided `Loc` parameter, which would result in a `TemplateSpecializationTypeLoc` obtained via `ASTContext::getTrivialTypeSourceInfo` being displayed as always having a `template` prefix (since the presence of the keyword is not stored anywhere else).
This patch fixes the display of characters appearing in LHS or RHS of == expression in notes to static assertion failure.
This applies C-style escape if the printed character is a special character. This also adds a numerical value displayed next to the character representation.
This also tries to print multi-byte characters if the user-provided expression is multi-byte char type.
Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D155610
Emiting an error on unexpected encoding prefix - which was allowed before C++26 -
caused build errors for a few users.
This downgrade the error to a warning on older language modes and C.
Reviewed By: aaron.ballman, hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D156596
This patch proposes to handle in an uniform fashion
the parsing of strings that are never evaluated,
in asm statement, static assert, attrributes, extern,
etc.
Unevaluated strings are UTF-8 internally and so currently
behave as narrow strings, but these things will diverge with
D93031.
The big question both for this patch and the P2361 paper
is whether we risk breaking code by disallowing
encoding prefixes in this context.
I hope this patch may allow to gather some data on that.
Future work:
Improve the rendering of unicode characters, line break
and so forth in static-assert messages
Reviewed By: aaron.ballman, shafik
Differential Revision: https://reviews.llvm.org/D105759
There are some simple messages where an expansion isn't particularly
helpful or needed. We aim to eliminate expansions that don't add much
value for user (this will give us slightly more room or prioritise to
have longer diagnostics elsewhere).
The test case for which it has been tested:
```
constexpr auto is_gitlab = false;
constexpr auto is_weekend = false;
static_assert(is_gitlab or is_weekend);
```
Previous warning/error message:
```
<source>:4:1: error: static assertion failed due to requirement 'is_gitlab || is_weekend'
static_assert(is_gitlab or is_weekend);
^ ~~~~~~~~~~~~~~~~~~~~~~~
<source>:4:25: note: expression evaluates to 'false || false'
static_assert(is_gitlab or is_weekend);
~~~~~~~~~~^~~~~~~~~~~~~
```
Currrent warning/error message:
```
<source>:4:1: error: static assertion failed due to requirement 'is_gitlab'
static_assert(is_gitlab or is_weekend);
^ ~~~~~~~~~
```
This patch aims to remove some redundant cases of static assert messages
where the expansions are particularly unhelpful. In this particular
patch, we have ignored the printing of diagnostic warnings for binary
operators with logical OR operations.
This is done to prioritise and prefer to emit longer diagnostic
warnings for more important concerns elsewhere.
Differential Revision: https://reviews.llvm.org/D146376
This allows `static_assert(false)` to not be ill-formed
in template definitions.
This change is applied as a DR in all C++ modes.
Of notes, a couple of tests were relying of the eager nature
of static_assert
* test/SemaTemplate/instantiation-dependence.cpp
* test/SemaTemplate/instantiate-var-template.cpp
I don't know if the changes to `static_assert`
still allow that sort of tests to be expressed.
Reviewed By: #clang-language-wg, erichkeane, aaron.ballman
Differential Revision: https://reviews.llvm.org/D144285
For failed static assertions, try to take the expression apart and print
useful information about why it failed. In particular, look at binary
operators and print the compile-time evaluated value of the LHS/RHS.
Differential Revision: https://reviews.llvm.org/D130894
This patch rewords the static assert diagnostic output. Failing a
_Static_assert in C should not report that static_assert failed. This
changes the wording to be more like GCC and uses "static assertion"
when possible instead of hard coding the name. This also changes some
instances of 'static_assert' to instead be based on the token in the
source code.
Differential Revision: https://reviews.llvm.org/D129048
Looks like we again are going to have problems with libcxx tests that
are overly specific in their dependency on clang's diagnostics.
This reverts commit 6542cb55a3eb115b1c3592514590a19987ffc498.
This patch is basically the rewording of the static assert statement's
output(error) on screen after failing. Failing a _Static_assert in C
should not report that static_assert failed. It’d probably be better to
reword the diagnostic to be more like GCC and say “static assertion”
failed in both C and C++.
consider a c file having code
_Static_assert(0, "oh no!");
In clang the output is like:
<source>:1:1: error: static_assert failed: oh no!
_Static_assert(0, "oh no!");
^ ~
1 error generated.
Compiler returned: 1
Thus here the "static_assert" is not much good, it will be better to
reword it to the "static assertion failed" to more generic. as the gcc
prints as:
<source>:1:1: error: static assertion failed: "oh no!"
1 | _Static_assert(0, "oh no!");
| ^~~~~~~~~~~~~~
Compiler returned: 1
The above can also be seen here. This patch is about rewording
the static_assert to static assertion.
Differential Revision: https://reviews.llvm.org/D129048
This reverts commit b7e77ff25fb2412f6ab6d6cc756666b0e2f97bd3.
Reason: Broke sanitizer builds bots + libcxx. 'static assertion
expression is not an integral constant expression'. More details
available in the Phabricator review: https://reviews.llvm.org/D129048
This patch rewords the static assert diagnostic output. Failing a
_Static_assert in C should not report that static_assert failed. This
changes the wording to be more like GCC and uses "static assertion"
when possible instead of hard coding the name. This also changes some
instances of 'static_assert' to instead be based on the token in the
source code.
Differential Revision: https://reviews.llvm.org/D129048
Introduce an off-by default `-Winvalid-utf8` warning
that detects invalid UTF-8 code units sequences in comments.
Invalid UTF-8 in other places is already diagnosed,
as that cannot appear in identifiers and other grammar constructs.
The warning is off by default as its likely to be somewhat disruptive
otherwise.
This warning allows clang to conform to the yet-to be approved WG21
"P2295R5 Support for UTF-8 as a portable source file encoding"
paper.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D128059
This reverts commit cc309721d20c8e544ae7a10a66735ccf4981a11c because it
breaks the following tests on GreenDragon:
TestDataFormatterObjCCF.py
TestDataFormatterObjCExpr.py
TestDataFormatterObjCKVO.py
TestDataFormatterObjCNSBundle.py
TestDataFormatterObjCNSData.py
TestDataFormatterObjCNSError.py
TestDataFormatterObjCNSNumber.py
TestDataFormatterObjCNSURL.py
TestDataFormatterObjCPlain.py
TestDataFormatterObjNSException.py
https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/45288/
Introduce an off-by default `-Winvalid-utf8` warning
that detects invalid UTF-8 code units sequences in comments.
Invalid UTF-8 in other places is already diagnosed,
as that cannot appear in identifiers and other grammar constructs.
The warning is off by default as its likely to be somewhat disruptive
otherwise.
This warning allows clang to conform to the yet-to be approved WG21
"P2295R5 Support for UTF-8 as a portable source file encoding"
paper.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D128059
Introduce an off-by default `-Winvalid-utf8` warning
that detects invalid UTF-8 code units sequences in comments.
Invalid UTF-8 in other places is already diagnosed,
as that cannot appear in identifiers and other grammar constructs.
The warning is off by default as its likely to be somewhat disruptive
otherwise.
This warning allows clang to conform to the yet-to be approved WG21
"P2295R5 Support for UTF-8 as a portable source file encoding"
paper.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D128059
This reverts commit 4174f0ca618b467571b43cff12cbe4c4239670f8.
Also revert follow-up "[Clang] Fix invalid utf-8 detection"
This reverts commit bf45e27a676d87944f1f13d5f0d0f39935fc4010.
The second commit broke tests, see comments on
https://reviews.llvm.org/D129223, and it sounds like the first
commit isn't valid without the second one. So reverting both for now.
Introduce an off-by default `-Winvalid-utf8` warning
that detects invalid UTF-8 code units sequences in comments.
Invalid UTF-8 in other places is already diagnosed,
as that cannot appear in identifiers and other grammar constructs.
The warning is off by default as its likely to be somewhat disruptive
otherwise.
This warning allows clang to conform to the yet-to be approved WG21
"P2295R5 Support for UTF-8 as a portable source file encoding"
paper.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D128059
Display 'static_assert failed: message' instead of
'static_assert failed "message"' to be consistent
with other implementations and be slightly more
readable.
Reviewed By: #libc, aaron.ballman, philnik, Mordante
Differential Revision: https://reviews.llvm.org/D128844
Instead of dumping the string literal (which
quotes it and escape every non-ascii symbol),
we can use the content of the string when it is a
8 byte string.
Wide, UTF-8/UTF-16/32 strings are still completely
escaped, until we clarify how these entities should
behave (cf https://wg21.link/p2361).
`FormatDiagnostic` is modified to escape
non printable characters and invalid UTF-8.
This ensures that unicode characters, spaces and new
lines are properly rendered in static messages.
This make clang more consistent with other implementation
and fixes this tweet
https://twitter.com/jfbastien/status/1298307325443231744 :)
Of note, `PaddingChecker` did print out new lines that were
later removed by the diagnostic printing code.
To be consistent with its tests, the new lines are removed
from the diagnostic.
Unicode tables updated to both use the Unicode definitions
and the Unicode 14.0 data.
U+00AD SOFT HYPHEN is still considered a print character
to match existing practices in terminals, in addition of
being considered a formatting character as per Unicode.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D108469
Instead of dumping the string literal (which
quotes it and escape every non-ascii symbol),
we can use the content of the string when it is a
8 byte string.
Wide, UTF-8/UTF-16/32 strings are still completely
escaped, until we clarify how these entities should
behave (cf https://wg21.link/p2361).
`FormatDiagnostic` is modified to escape
non printable characters and invalid UTF-8.
This ensures that unicode characters, spaces and new
lines are properly rendered in static messages.
This make clang more consistent with other implementation
and fixes this tweet
https://twitter.com/jfbastien/status/1298307325443231744 :)
Of note, `PaddingChecker` did print out new lines that were
later removed by the diagnostic printing code.
To be consistent with its tests, the new lines are removed
from the diagnostic.
Unicode tables updated to both use the Unicode definitions
and the Unicode 14.0 data.
U+00AD SOFT HYPHEN is still considered a print character
to match existing practices in terminals, in addition of
being considered a formatting character as per Unicode.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D108469
Support Narrowing conversions to bool in if constexpr condition
under C++23 language mode.
Only if constexpr is implemented as the behavior of static_assert
is already conforming. Still need to work on explicit(bool) to
complete support.
Our diagnostics relating to static assertions were a bit confused. For
instance, when in MS compatibility mode in C (where we accept
static_assert even without including <assert.h>), we would fail
to warn the user that they were using the wrong spelling (even in
pedantic mode), we were missing a compatibility warning about using
_Static_assert in earlier standards modes, diagnostics for the optional
message were not reflected in C as they were in C++, etc.
Summary:
In our codebase, `static_assert(std::some_type_trait<Ts...>::value, "msg")`
(where `some_type_trait` is an std type_trait and `Ts...` is the
appropriate template parameters) account for 11.2% of the `static_assert`s.
In these cases, the `Ts` are typically not spelled out explicitly, e.g.
`static_assert(std::is_same<SomeT::TypeT, typename SomeDependentT::value_type>::value, "message");`
The diagnostic when the assert fails is typically not very useful, e.g.
`static_assert failed due to requirement 'std::is_same<SomeT::TypeT, typename SomeDependentT::value_type>::value' "message"`
This change makes the diagnostic spell out the types explicitly , e.g.
`static_assert failed due to requirement 'std::is_same<int, float>::value' "message"`
See tests for more examples.
After this is submitted, I intend to handle
`static_assert(!std::some_type_trait<Ts...>::value, "msg")`,
which is another 6.6% of static_asserts.
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D54903
llvm-svn: 348239
When a static_assert fails, dig out a specific condition to diagnose,
using the same logic that we use to find the enable_if condition to
diagnose.
llvm-svn: 313315
It's better not to rely on the diagnostics engine to pretty print the
argument to decltype. Instead, exercise the functionality in
DeclPrinterTest.
llvm-svn: 239197
We would crash in the DeclPrinter trying to pretty-print the
static_assert message. C++1z-style assertions don't have a message so
we would crash.
This fixes PR23756.
llvm-svn: 239170
String literals (including unicode ones) can contain non-Unicode codepoints
if they were written using \x or similar. Write those out using \x, but be
careful that the following character can't be misinterpreted as part of the
\x escape sequence. Convert UTF-16 surrogate pairs back to codepoints before
rendering them.
llvm-svn: 154069
therefore not creating ElaboratedTypes, which are still pretty-printed
with the written tag).
Most of these testcase changes were done by script, so don't feel too
sorry for my fingers.
llvm-svn: 98149
- 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
