[clang][ExprConst] Add diagnostics for invalid binary arithmetic (#118475)

... between unrelated declarations or literals.

Leaving this small (I haven't run the whole test suite locally) to get
som

[clang][ExprConst] Add diagnostics for invalid binary arithmetic (#118475)

... between unrelated declarations or literals.

Leaving this small (I haven't run the whole test suite locally) to get
some feedback on the wording and implementation first.

The output of the sample in
https://github.com/llvm/llvm-project/issues/117409 is now:
```console
./array.cpp:57:6: warning: expression result unused [-Wunused-value]
57 | am - aj.af();
| ~~ ^ ~~~~~~~
./array.cpp:70:8: error: call to consteval function 'L::L<bx>' is not a constant expression
70 | q(0, [] {
| ^
./array.cpp:57:6: note: arithmetic on addresses of literals has unspecified value
57 | am - aj.af();
| ^
./array.cpp:62:5: note: in call to 'al(&""[0], {&""[0]})'
62 | al(bp.af(), k);
| ^~~~~~~~~~~~~~
./array.cpp:70:8: note: in call to 'L<bx>({})'
70 | q(0, [] {
| ^~~~
71 | struct bx {
| ~~~~~~~~~~~
72 | constexpr operator ab<g<l<decltype(""[0])>::e>::e>() { return t(""); }
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
73 | };
| ~~
74 | return bx();
| ~~~~~~~~~~~~
75 | }());
| ~~~
```

The output for
```c++
int a, b;
constexpr int n = &b - &a
```

is now:
```console
./array.cpp:80:15: error: constexpr variable 'n' must be initialized by a constant expression
80 | constexpr int n = &b - &a;
| ^ ~~~~~~~
./array.cpp:80:22: note: arithmetic involving '&b' and '&a' has unspecified value
80 | constexpr int n = &b - &a;
| ^
1 error generated.

```

show more ...

[clang][bytecode] Consider unknown-size arrays in memcpy/memcmp (#121462)

When emitting diagnostics for the number of elements.

[clang][bytecode] Consider start index when copying composite array (#121461)

... elements.

[clang][bytecode] Check memove/memcpy for available elements (#121383)

Both destination and source pointer need to have at least as many
elements as requested.

[clang][bytecode] Support pointers in __builtin_mem{move,cpy} (#120560)

Unfortunately, that means we can't use the __builtin_bit_cast
implementation for this.

[clang][bytecode] Handle builtin_wmemcmp (#120070)

[clang][bytecode] Handle __builtin_bcmp (#119678)

... the same as `__builtin_memcmp`. Also fix a bug we still had when we
couldn't find a difference in the two inputs after `Size` bytes.

[clang][bytecode] Handle __builtin_memcmp (#119544)

[clang][bytecode] Check for overlapping memcpy regions (#119535)

[clang][bytecode] Allow checking builtin functions... (#119328)

... in checkingPotentialConstantExpression mode. This is what the
current interpreter does, yet it doesn't do so for
`__builtin_operat

[clang][bytecode] Allow checking builtin functions... (#119328)

... in checkingPotentialConstantExpression mode. This is what the
current interpreter does, yet it doesn't do so for
`__builtin_operator_new`.

show more ...

[clang][bytecode] Reject memcpy sizes with element size remainder (#119209)

[clang][bytecode] Handle __builtin_strncmp (#119208)

[clang][bytecode] Handle __builtin_wcslen (#119187)

Handle different char widths in builtin_strlen.

[clang][bytecode] Pass __builtin_memcpy size along (#118649)

To DoBitCastPtr, so we know how many bytes we want to read.

Revert "[clang][bytecode] Handle __builtin_wcslen (#118446)"

This reverts commit 89a0ee89973c3d213c4bc11c26b41eab67e06da0.

This breaks builders:
https://lab.llvm.org/buildbot/#/builders/13/builds/3

Revert "[clang][bytecode] Handle __builtin_wcslen (#118446)"

This reverts commit 89a0ee89973c3d213c4bc11c26b41eab67e06da0.

This breaks builders:
https://lab.llvm.org/buildbot/#/builders/13/builds/3885

show more ...

[clang][bytecode] Reject memcpy dummy pointers after null check (#118460)

To match the diagnostic output of the current interpreter.

[clang][bytecode] Initialize elements in __builtin_elementwise_popcount (#118457)

[clang][bytecode] Handle __builtin_wcslen (#118446)

... just like strlen.

[clang][bytecode] Handle memmove like memcpy (#118431)

This is the same thing for us, except for diagnostic differences.

[clang][bytecode] Check __builtin_memcpy for null pointers (#118313)

[clang][bytecode] Implement __builtin_elementwise_popcount (#118307)

[clang][bytecode] Implement __builtin_reduce_xor (#118299)

[clang][bytecode] Implement __builtin_reduce_or (#118292)

[clang][bytecode] Implement __builtin_reduce_and (#118289)

[clang][bytecode] Implement __builtin_reduce_mul (#118287)