1748395 - Use `if constexpr` for expressions that can be determined at compile time

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, task)

Description

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

In gfxFont.cpp and gfxTextRun.cpp, some template methods have logic that is intended only for 8-bit or 16-bit text such as [1].

if (sizeof(T) == sizeof(char16_t)) {
    ....
}

This kind of if expression can be determined at the compile time, so it's better to use if constexpr.

[1] https://searchfox.org/mozilla-central/rev/855814f769ac55bbb6a00e2170a6a876ab4cff3a/gfx/thebes/gfxFont.cpp#2971-2973

Comment 1

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Bug 1748395 - Use `if constexpr` for expressions that can be determined at compile time. r?#layout-reviewers

The compiler might already be smart enough to not generate code in an
if-statement that guarantees to be false at compile time. However it's no harm
to make it explicit by using if constexpr.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/01217db0e1fc
Use `if constexpr` for expressions that can be determined at compile time. r=emilio

Comment 3

[Marian-Vasile Laza]

Backed out changeset 01217db0e1fc (Bug 1748395) for causing build bustages on gfxFont.cpp.
Backout link
Push with failures
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Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7ee415205518
Use `if constexpr` for expressions that can be determined at compile time. r=emilio

Comment 5

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/7ee415205518