Bug 273694 – Replace potentially more confusing decltype() usage with template lambdas where possible

• Component: New Bugs
• Status: RESOLVED FIXED

[Sam Weinig]

A somewhat common patter in WebCore is for a callsite to use a generic lambda but still want to know what the type of the generic argument was. Something like:

function([](auto parameter) {
    using Type = std::decay_t<decltype(parameter)>;

    ...
});

This was necessary in the past due to the lack of template lambdas, but now we have them and this can be come:

function([]<typename Type>(Type parameter) {
    ...
});

[Sam Weinig]

Pull request: https://github.com/WebKit/WebKit/pull/28109

[Radar WebKit Bug Importer]

<rdar://problem/127506433>

[EWS]

Committed 278358@main (5fe8dd6a3b46): <https://commits.webkit.org/278358@main>

Reviewed commits have been landed. Closing PR #28109 and removing active labels.

[Diego Pino]

Build bot 'GTK-Linux-64-bit-Release-Debian-11-Build' (and others using GCC10) is failing after this patch with the following build error:

https://build.webkit.org/#/builders/992

```
../../../Source/WebCore/platform/graphics/ColorSpace.h:136:69: error: expected ‘(’ before ‘{’ token
  136 |     return callWithColorType<T>(colorSpace, [&]<typename ColorType> {
      |                                                                     ^
      |                                                                     (
```

[Diego Pino]

Re-opening for pull request https://github.com/webkit/webkit/pull/28151

[EWS]

Committed 278386@main (ab7b68fdc266): <https://commits.webkit.org/278386@main>

Reviewed commits have been landed. Closing PR #28151 and removing active labels.