1762933 - Fix compiler errors on C++20

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[André Bargull [:anba]]

Three issues currently prevent compiling to C++20:

1. The static_cast in DECLARE_ONE_BOOL_OPERATOR can generate casts between incompatible types.

• This can be fixed by only using static_cast for integral types.

2. Deprecated arithmetic conversion on enumerations.

• http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1120r0.html
• This also affects the ARM64 simulator, but any updates there should happen in the main repository first.

3. Deprecated implicit this capture.

• http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0409r2.html

Comment 1

[André Bargull [:anba]]

Attachment: Bug 1762933 - Part 1: Avoid static_cast on non-integral types. r=tcampbell!

Otherwise we can for example end up with generating static_cast between const and non-const pointers.

Comment 2

[André Bargull [:anba]]

Attachment: Bug 1762933 - Part 2: Fix implicit coercion between different enum types. r=tcampbell!

Use std::underlying_type_t to convert from an enum to its underlying type.

Depends on D142855

Comment 3

[André Bargull [:anba]]

Attachment: Bug 1762933 - Part 3: Fix implicit this-capture in lambdas. r=tcampbell!

Implicit this capture through = is deprecated in C++20.

Depends on D142856

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/14e582a97f5f
Part 1: Avoid static_cast on non-integral types. r=tcampbell
https://hg.mozilla.org/integration/autoland/rev/b1a9775198ab
Part 2: Fix implicit coercion between different enum types. r=tcampbell
https://hg.mozilla.org/integration/autoland/rev/a9a3140427ea
Part 3: Fix implicit this-capture in lambdas. r=tcampbell

Comment 5

[Lars T Hansen [:lth]]

(In reply to André Bargull [:anba] [back from break; working through mail backlog] from comment #0)

• This also affects the ARM64 simulator, but any updates there should happen in the main repository first.

FWIW, the chances of us ever pulling another VIXL version (with the simulator) are very small; for several years we've been hacking freely on our local copy.

Comment 6

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/14e582a97f5f
https://hg.mozilla.org/mozilla-central/rev/b1a9775198ab
https://hg.mozilla.org/mozilla-central/rev/a9a3140427ea