[clang][Interp] Only emit function_param_value_unknown in C++11 (#67990)

This is also what the current interpreter does.

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

show more ...

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

show more ...

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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[Clang] Fix missing diagnostic for non-standard layout type in `offsetof` (#65246)

Fixes #64619

Clang warns diagnostic for non-standard layout types in `offsetof` only
if they are in evaluated c

[Clang] Fix missing diagnostic for non-standard layout type in `offsetof` (#65246)

Fixes #64619

Clang warns diagnostic for non-standard layout types in `offsetof` only
if they are in evaluated context. With this patch, you'll also get
diagnostic if you use `offsetof` on non-standard layout types in any
other contexts

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[clang][Interp] Implement __builtin_offsetof

Differential Revision: https://reviews.llvm.org/D156400

Diagnose extensions in 'offsetof'

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof.
Clang supports defining a type

Diagnose extensions in 'offsetof'

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof.
Clang supports defining a type as the first argument as a conforming
extension due to how many projects use the construct in C99 and earlier
to calculate the alignment of a type. GCC also supports defining a type
as the first argument.

This adds extension warnings and documentation for the functionality
Clang explicitly supports.

Fixes #57065
Reverts the revert of 39da55e8f548a11f7dadefa73ea73d809a5f1729

Co-authored-by: Yingchi Long <i@lyc.dev>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>

Differential Revision: https://reviews.llvm.org/D133574

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Revert "Diagnose extensions in 'offsetof'"

This reverts commit f1f0a0d8e8fdd2e534d9423b2e64c6b8aaa53aee.

Causes crashes on

$ echo 'typedef int a; void c() { __builtin_offsetof(struct {a b}, b); }'

Revert "Diagnose extensions in 'offsetof'"

This reverts commit f1f0a0d8e8fdd2e534d9423b2e64c6b8aaa53aee.

Causes crashes on

$ echo 'typedef int a; void c() { __builtin_offsetof(struct {a b}, b); }' | bin/clang -cc1 -emit-llvm -o /dev/null - -x c

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Diagnose extensions in 'offsetof'

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof.
Clang supports defining a type

Diagnose extensions in 'offsetof'

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof.
Clang supports defining a type as the first argument as a conforming
extension due to how many projects use the construct in C99 and earlier
to calculate the alignment of a type. GCC also supports defining a type
as the first argument.

This adds extension warnings and documentation for the functionality
Clang explicitly supports.

Fixes #57065

Co-authored-by: Yingchi Long <i@lyc.dev>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>

show more ...

Revert "[C2x] reject type definitions in offsetof"

This reverts commit e327b52766ed497e4779f4e652b9ad237dfda8e6.

[C2x] reject type definitions in offsetof

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof. After
this patch clang

[C2x] reject type definitions in offsetof

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm made very
clear that it is an UB having type definitions with in offsetof. After
this patch clang will reject any type definitions in __builtin_offsetof.

Fixes https://github.com/llvm/llvm-project/issues/57065

```
local/offsetof.c:10:38: error: 'struct S' cannot be defined in '__builtin_offsetof'
return __builtin_offsetof(struct S{ int a, b;}, a);
^
```

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

Differential Revision: https://reviews.llvm.org/D133574

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[Lit Test] Updated 26 Lit tests to be C++11 compatible.

Expected diagnostics have been expanded to vary by C++ dialect.
RUN line has also been expanded to: default, C++98/03 and C++11.

llvm-svn: 25

[Lit Test] Updated 26 Lit tests to be C++11 compatible.

Expected diagnostics have been expanded to vary by C++ dialect.
RUN line has also been expanded to: default, C++98/03 and C++11.

llvm-svn: 252785

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Sema: Consider it an error to apply __builtin_offsetof to a member in a virtual base

icc 13 and g++ 4.9 both reject this while we would crash.

Fixes PR17578.

llvm-svn: 192674

Perform lvalue-to-rvalue conversions on __builtin_offsetof array argument index
before typechecking, as suggested by John.

llvm-svn: 142308

PR7769: Fix references to anonymous structs/unions in base classes in
offsetof expressions.

llvm-svn: 110327

Implement support for variable length arrays in C++. VLAs are limited
in several important ways:

- VLAs of non-POD types are not permitted.
- VLAs cannot be used in conjunction with C++ template

Implement support for variable length arrays in C++. VLAs are limited
in several important ways:

- VLAs of non-POD types are not permitted.
- VLAs cannot be used in conjunction with C++ templates.

These restrictions are intended to keep VLAs out of the parts of the
C++ type system where they cause the most trouble. Fixes PR5678 and
<rdar://problem/8013618>.

llvm-svn: 104443

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Teach __builtin_offsetof to compute the offsets of members of base
classes, since we only warn (not error) on offsetof() for non-POD
types. We store the base path within the OffsetOfExpr itself, then

Teach __builtin_offsetof to compute the offsets of members of base
classes, since we only warn (not error) on offsetof() for non-POD
types. We store the base path within the OffsetOfExpr itself, then
evaluate the offsets within the constant evaluator.

llvm-svn: 102571

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Diagnose __builtin_offsetof expressions that refer to bit-fields

llvm-svn: 102548

Completely reimplement __builtin_offsetof, based on a patch by Roberto
Amadini.

This change introduces a new expression node type, OffsetOfExpr, that
describes __builtin_offsetof. Previously, __buil

Completely reimplement __builtin_offsetof, based on a patch by Roberto
Amadini.

This change introduces a new expression node type, OffsetOfExpr, that
describes __builtin_offsetof. Previously, __builtin_offsetof was
implemented using a unary operator whose subexpression involved
various synthesized array-subscript and member-reference expressions,
which was ugly and made it very hard to instantiate as a
template. OffsetOfExpr represents the AST more faithfully, with proper
type source information and a more compact representation.

OffsetOfExpr also has support for dependent __builtin_offsetof
expressions; it can be value-dependent, but will never be
type-dependent (like sizeof or alignof). This commit introduces
template instantiation for __builtin_offsetof as well.

There are two major caveats to this patch:

1) CodeGen cannot handle the case where __builtin_offsetof is not a
constant expression, so it produces an error. So, to avoid
regressing in C, we retain the old UnaryOperator-based
__builtin_offsetof implementation in C while using the shiny new
OffsetOfExpr implementation in C++. The old implementation can go
away once we have proper CodeGen support for this case, which we
expect won't cause much trouble in C++.

2) __builtin_offsetof doesn't work well with non-POD class types,
particularly when the designated field is found within a base
class. I will address this in a subsequent patch.

Fixes PR5880 and a bunch of assertions when building Boost.Python
tests.

llvm-svn: 102542

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When pretty-printing tag types, only print the tag if we're in C (and
therefore not creating ElaboratedTypes, which are still pretty-printed
with the written tag).

Most of these testcase changes wer

When pretty-printing tag types, only print the tag if we're in C (and
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

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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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Suppress warnings and errors about certain uses of non-POD types (in
__builtin_offsetof, passing through an ellipsis) when we're in an
unevaluated context. This is the first part of the fix to PR5761

Suppress warnings and errors about certain uses of non-POD types (in
__builtin_offsetof, passing through an ellipsis) when we're in an
unevaluated context. This is the first part of the fix to PR5761,
which deals with the simple case of an unevaluated context.

llvm-svn: 91210

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Make sure to call PerformObjectMemberConversion where necessary.

llvm-svn: 90555

Fix/re-enable test.

llvm-svn: 70800

Disable this test case, I'm tired of seeing red. :)

llvm-svn: 70799