[clang][Interp] Redo variable (re)visiting

Depending on the circumstances we visit variables in, we need to
be careful about when to destroy their temporaries and whether to
emit a Ret op at all or

[clang][Interp] Redo variable (re)visiting

Depending on the circumstances we visit variables in, we need to
be careful about when to destroy their temporaries and whether to
emit a Ret op at all or not.

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[Clang][Sema]: Allow copy constructor side effects (#81127)

Copy constructors can have initialization with side effects, and thus
clang should not emit a warning when -Wunused-variable is used in t

[Clang][Sema]: Allow copy constructor side effects (#81127)

Copy constructors can have initialization with side effects, and thus
clang should not emit a warning when -Wunused-variable is used in this
context. Currently however, a warning is emitted.

Now, compilation happens without warnings.

Fixes #79518

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Diagnose use of VLAs in C++ by default

Reapplication of 7339c0f782d5c70e0928f8991b0c05338a90c84c with a fix
for a crash involving arrays without a size expression.

Clang supports VLAs in C++ as an

Diagnose use of VLAs in C++ by default

Reapplication of 7339c0f782d5c70e0928f8991b0c05338a90c84c with a fix
for a crash involving arrays without a size expression.

Clang supports VLAs in C++ as an extension, but we currently only warn
on their use when you pass -Wvla, -Wvla-extension, or -pedantic.
However, VLAs as they're expressed in C have been considered by WG21
and rejected, are easy to use accidentally to the surprise of users
(e.g., https://ddanilov.me/default-non-standard-features/), and they
have potential security implications beyond constant-size arrays
(https://wiki.sei.cmu.edu/confluence/display/c/ARR32-C.+Ensure+size+arguments+for+variable+length+arrays+are+in+a+valid+range).
C++ users should strongly consider using other functionality such as
std::vector instead.

This seems like sufficiently compelling evidence to warn users about
VLA use by default in C++ modes. This patch enables the -Wvla-extension
diagnostic group in C++ language modes by default, and adds the warning
group to -Wall in GNU++ language modes. The warning is still opt-in in
C language modes, where support for VLAs is somewhat less surprising to
users.

RFC: https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109
Fixes https://github.com/llvm/llvm-project/issues/62836
Differential Revision: https://reviews.llvm.org/D156565

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Revert "Diagnose use of VLAs in C++ by default"

This reverts commit 7339c0f782d5c70e0928f8991b0c05338a90c84c.

Breaks bots:
https://lab.llvm.org/buildbot/#/builders/139/builds/51875
https://lab.llvm

Revert "Diagnose use of VLAs in C++ by default"

This reverts commit 7339c0f782d5c70e0928f8991b0c05338a90c84c.

Breaks bots:
https://lab.llvm.org/buildbot/#/builders/139/builds/51875
https://lab.llvm.org/buildbot/#/builders/164/builds/45262

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Diagnose use of VLAs in C++ by default

Clang supports VLAs in C++ as an extension, but we currently only warn
on their use when you pass -Wvla, -Wvla-extension, or -pedantic.
However, VLAs as they'r

Diagnose use of VLAs in C++ by default

Clang supports VLAs in C++ as an extension, but we currently only warn
on their use when you pass -Wvla, -Wvla-extension, or -pedantic.
However, VLAs as they're expressed in C have been considered by WG21
and rejected, are easy to use accidentally to the surprise of users
(e.g., https://ddanilov.me/default-non-standard-features/), and they
have potential security implications beyond constant-size arrays
(https://wiki.sei.cmu.edu/confluence/display/c/ARR32-C.+Ensure+size+arguments+for+variable+length+arrays+are+in+a+valid+range).
C++ users should strongly consider using other functionality such as
std::vector instead.

This seems like sufficiently compelling evidence to warn users about
VLA use by default in C++ modes. This patch enables the -Wvla-extension
diagnostic group in C++ language modes by default, and adds the warning
group to -Wall in GNU++ language modes. The warning is still opt-in in
C language modes, where support for VLAs is somewhat less surprising to
users.

RFC: https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109
Fixes https://github.com/llvm/llvm-project/issues/62836
Differential Revision: https://reviews.llvm.org/D156565

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[Sema] add test cases for D152495 NFC

Ensure these don't regress the next time we reland D152495.

Link: https://github.com/ClangBuiltLinux/linux/issues/1926

Reviewed By: cor3ntin, MaskRay

Differe

[Sema] add test cases for D152495 NFC

Ensure these don't regress the next time we reland D152495.

Link: https://github.com/ClangBuiltLinux/linux/issues/1926

Reviewed By: cor3ntin, MaskRay

Differential Revision: https://reviews.llvm.org/D159307

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Revert "Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions""

This reverts commit 92023b15099012a657da07ebf49dd7d94a260f84.

Further issues were uncovered:
-

Revert "Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions""

This reverts commit 92023b15099012a657da07ebf49dd7d94a260f84.

Further issues were uncovered:
- False positive -Wunused-variable on function-static variables with the
used attribute. https://github.com/ClangBuiltLinux/linux/issues/1926
A test case needs to be added for this.
- Request for a new flag for these.
https://reviews.llvm.org/D152495#4628877
https://reviews.llvm.org/D152495#4628887

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Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

This patch marks the declarations with initializations in condition expressions such as
if (int var = ini

Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

This patch marks the declarations with initializations in condition expressions such as
if (int var = init) as unused and unreferenced so that -Wunused can warn on them.

Fixes https://github.com/llvm/llvm-project/issues/61681

Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D152495

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Revert "Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions""

This causes a lot of warning in sanitizer build:
https://lab.llvm.org/buildbot/#/builders/258/bu

Revert "Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions""

This causes a lot of warning in sanitizer build:
https://lab.llvm.org/buildbot/#/builders/258/builds/5424
https://lab.llvm.org/buildbot/#/builders/36/builds/36560

This reverts commit 8e329caa944c377c51ef567d5aa67cfac9ffd0fa.

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Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

This patch marks the declarations with initializations in condition expressions such as
if (int var = ini

Reland "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

This patch marks the declarations with initializations in condition expressions such as
if (int var = init) as unreferenced so that -Wunused can warn on them.

Fixes https://github.com/llvm/llvm-project/issues/61681

Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D152495

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Revert "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

Broke sanitizer buildbot:
https://lab.llvm.org/buildbot/#/builders/240/builds/12947
https://lab.llvm.org/

Revert "[Clang][SemaCXX] Add unused warning for variables declared in condition expressions"

Broke sanitizer buildbot:
https://lab.llvm.org/buildbot/#/builders/240/builds/12947
https://lab.llvm.org/buildbot/#/builders/19/builds/18369

Reverting while I figure out the cause.

This reverts commit bd0ed0abc31fa5a49e87eeca7aa872e7f6e4d1e7.

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[Clang][SemaCXX] Add unused warning for variables declared in condition expressions

This patch marks the declarations with initializations in condition expressions such as
if (int var = init) as unr

[Clang][SemaCXX] Add unused warning for variables declared in condition expressions

This patch marks the declarations with initializations in condition expressions such as
if (int var = init) as unreferenced so that -Wunused can warn on them.

Fixes https://github.com/llvm/llvm-project/issues/61681

Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D152495

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[Clang] Do not warn on unused lifetime-extending vars with side effects...

const auto & var = ObjectWithSideEffects();

Fixes https://github.com/llvm/llvm-project/issues/54489

Reviewed By: aaron.ba

[Clang] Do not warn on unused lifetime-extending vars with side effects...

const auto & var = ObjectWithSideEffects();

Fixes https://github.com/llvm/llvm-project/issues/54489

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D122661

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Suppress -Wwarn-unused-variables when we don't know the constructor

This warning is supposed to be suppressed when the
constructor/destructor are non-trivial, since it might be a RAII type.
However,

Suppress -Wwarn-unused-variables when we don't know the constructor

This warning is supposed to be suppressed when the
constructor/destructor are non-trivial, since it might be a RAII type.
However, if the type has a trivial destructor and the constructor hasn't
been resolved (since it is called with dependent arguments), we were
still warning.

This patch suppresses the warning if the type could possibly have a
be a non-trivial constructor call. Note that this does not take the
arity of the constructors into consideration, so it might suppress
the warning in cases where it isn't possible to call a non-trivial
constructor.

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C++ DR2387: a variable template declared wtih (or instantiated with) a
const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

This reinstates pa

C++ DR2387: a variable template declared wtih (or instantiated with) a
const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

This reinstates part of r359048, reverted in r359076.

llvm-svn: 359260

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Revert r359048: C++ DR2387: a variable template declared wthi

The change breaks libc++ with the follwing error:

In file included from valarray:4:
.../include/c++/v1/valarray:1062:60: error: explici

Revert r359048: C++ DR2387: a variable template declared wthi

The change breaks libc++ with the follwing error:

In file included from valarray:4:
.../include/c++/v1/valarray:1062:60: error: explicit instantiation declaration of 'valarray<_Tp>' with internal linkage
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t))
^
.../include/c++/v1/valarray:1063:60: error: explicit instantiation declaration of '~valarray<_Tp>' with internal linkage
_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS valarray<size_t>::~valarray())

llvm-svn: 359076

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C++ DR2387: a variable template declared wtih (or instantiated with) a
const-qualified type is not implicitly given internal linkage. But a
variable template declared 'static' is.

llvm-svn: 359048

[Sema] Fix assertion failure when checking for unused variables in a dependent context.

llvm-svn: 316177

Re-land r315787, "[Sema] Warn about unused variables if we can constant evaluate the initializer."

The warnings in libc++ tests were fixed in the meantime.

llvm-svn: 315811

Revert rL315787, "[Sema] Warn about unused variables if we can constant evaluate the initializer."

check-libcxx dislikes it.

llvm-svn: 315806

[Sema] Warn about unused variables if we can constant evaluate the initializer.

If the variable construction can be constant evaluated it doesn't have
side effects, so removing it is always safe. We

[Sema] Warn about unused variables if we can constant evaluate the initializer.

If the variable construction can be constant evaluated it doesn't have
side effects, so removing it is always safe. We only try to evaluate
variables that are unused, there should be no impact on compile time.

Differential Revision: https://reviews.llvm.org/D38678

llvm-svn: 315787

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Simplify the test case from r285289.

This commit simplifies and clarifies the test code
that was added in r285289.

Suggested by David Blaikie.

llvm-svn: 285825

[Sema] -Wunused-variable warning for array variables should behave
similarly to scalar variables.

This commit makes the -Wunused-variable warning behaviour more consistent:
Now clang won't warn for

[Sema] -Wunused-variable warning for array variables should behave
similarly to scalar variables.

This commit makes the -Wunused-variable warning behaviour more consistent:
Now clang won't warn for array variables where it doesn't warn for scalar
variables.

rdar://24158862

Differential Revision: https://reviews.llvm.org/D25937

llvm-svn: 285289

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PR19558: don't produce an "unused variable" warning for a variable template partial specialization.

llvm-svn: 207260

PR19305: Don't issue -Wunused-variable warnings on variable templates. It's not
meaningful to odr-use the VarDecl inside a variable template. (Separately, it'd
be nice to track referenced-ness for te

PR19305: Don't issue -Wunused-variable warnings on variable templates. It's not
meaningful to odr-use the VarDecl inside a variable template. (Separately, it'd
be nice to track referenced-ness for templates, and warn on unused ones, but
that's really a distinct issue...)

Move a test that generates and tests a warning-suppressing error out to its own
test file, so it doesn't have weird effects on the other tests in the same file.

llvm-svn: 205448

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