1684089 - Replace MOZ_MUST_USE with [[nodiscard]] in js/src/wasm/

Status: RESOLVED FIXED

(Core :: JavaScript: WebAssembly, task, P3)

Description

[Chris Peterson [:cpeterson]]

The MOZ_MUST_USE macro is defined as clang's and gcc's nonstandard __attribute__((warn_unused_result)). Now that we compile as C++17 by default (bug 1560664), we can replace MOZ_MUST_USE with C++17's standard [[nodiscard]] attribute.

The [[nodiscard]] attribute must precede a function declaration's declaration specifiers (like static, extern, inline, or virtual). The __attribute__((warn_unused_result)) attribute does not have this order restriction.

Comment 1

[Chris Peterson [:cpeterson]]

Attachment: Bug 1684089 - Part 1: Replace MOZ_MUST_USE with [[nodiscard]] in js/src/wasm/. r?rhunt

The MOZ_MUST_USE macro is defined as clang's and gcc's nonstandard attribute((warn_unused_result)). Now that we compile as C++17 by default (bug 1560664), we can replace MOZ_MUST_USE with C++17's standard [[nodiscard]] attribute.

Comment 2

[Chris Peterson [:cpeterson]]

Attachment: Bug 1684089 - Part 2: Move [[nodiscard]] to the head of function declarations in js/src/wasm/. r?rhunt

The [[nodiscard]] attribute must precede a function declaration's declaration specifiers (like static, extern, inline, or virtual). The attribute((warn_unused_result)) attribute does not have this order restriction.

Depends on D100405

Comment 3

[Chris Peterson [:cpeterson]]

Attachment: Bug 1684089 - Part 3: Remove unnecessary #includes of Attributes.h for MOZ_MUST_USE in js/src/wasm/. r?rhunt

We don't need to #include Attributes.h now that we're using [[nodiscard]] instead of MOZ_MUST_USE.

Depends on D100406

Comment 4

[Chris Peterson [:cpeterson]]

Green Try build:

https://treeherder.mozilla.org/jobs?repo=try&revision=f0ab7b7ec0386af7c753f323aa146e00d91c7b3d

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/565c05bcf5a1
Part 1: Replace MOZ_MUST_USE with [[nodiscard]] in js/src/wasm/. r=rhunt
https://hg.mozilla.org/integration/autoland/rev/7aa213ad1741
Part 2: Move [[nodiscard]] to the head of function declarations in js/src/wasm/. r=rhunt
https://hg.mozilla.org/integration/autoland/rev/1f6486280356
Part 3: Remove unnecessary #includes of Attributes.h for MOZ_MUST_USE in js/src/wasm/. r=rhunt

Comment 6

[Razvan Maries]

https://hg.mozilla.org/mozilla-central/rev/565c05bcf5a1
https://hg.mozilla.org/mozilla-central/rev/7aa213ad1741
https://hg.mozilla.org/mozilla-central/rev/1f6486280356