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diff --git a/docs/writing-rust-code/update-policy.md b/docs/writing-rust-code/update-policy.md new file mode 100644 index 0000000000..f0d27a3b7d --- /dev/null +++ b/docs/writing-rust-code/update-policy.md @@ -0,0 +1,160 @@ +# Rust Update Policy + +We document here the decision making and planning around when we update the +Rust toolchains used and required to build Firefox. + +This allows contributors to know when new features will be usable, and +downstream packagers to know what toolchain will be required for each Firefox +release. Both benefit from the predictability of a schedule. + +## Policy + +### Official builds + +_We ship official stable Firefox with a stable Rust._ + +As a general rule, we update the Rust version used to build Firefox Nightly +soon after its release, unless it's less than 7 days away from a soft-freeze, +in which case we wait for the next Nightly train. + +We don't upgrade the Rust version in the beta or release branches of Firefox. + +The following exceptions apply: + +- We may use a Rust version from the Rust beta or nightly channels for new + platforms (e.g. we did so for Android, arm64 Windows and arm64 macOS), and + later upgrade when that Rust version becomes stable (we may even do so on the + Firefox beta branch). + +- We may skip the update (or backout the update) if major problems are + encountered (typically, we've had to do so because of build problems, crash + reporting bustage, or performance issues). + +### Developer builds + +_Local developer builds use whatever Rust toolchain is available on the +system._ + +Someone building Firefox can maintain the latest stable Rust with the `rustup` +or `mach bootstrap` tools, or try other variations. + +### Minimum Supported Rust Version + +_We will update the Minimum Supported Rust Version (MSRV) when required._ + +The MSRV will generally remain unchanged, until a newer version is required +by some code. + +When that happens, we'll prefer to update the MSRV to the strict minimum +required at that moment (e.g. if we require version 1.47.0, the currently used +Rust version is 1.51.0, and a crate needs 1.50.0, we'll prefer to update the +MSRV to 1.50.0 rather than 1.51.0). + +The MSRV won't be updated to a version of Rust that hasn't been used for +Firefox Nightly for at least 14 days. + +We expect ESR releases will keep their MSRV, so backporting security fixes may +require Rust compatibility work. + +### Rationale + +Historically, the Rust ecosystem quickly required new features provided by new +Rust compilers, which made it necessary to update the minimum supported version +quite often, and as such, a scheduled update was deemed a better trade-off. + +Fast-forward several years, and new Rust compiler releases more rarely sport +ground-breaking new features, which has reduced the necessity to update quite +significantly. + +On the flip side, in some instances, we have had to stick to specific versions +of the Rust compiler for extended periods of time because of e.g. regressions, +going against the schedule. + +## Schedule + +Here are the Rust versions for each Firefox version. + +- The "Uses" column indicates the version of Rust used to build + releases shipped to users. + +- The "MSRV" column indicates the minimum supported Rust version to build + the sources. + +| Firefox Version | Uses | MSRV | Rust "Uses" release date | Nightly Soft Freeze | Firefox release date | +|-----------------|------|----------|--------------------------|---------------------|----------------------| +| Firefox 56 | Rust 1.19.0 | 1.17.0 | 2017 April 27 | | 2017 September 26 +| Firefox 57 | Rust 1.19.0 | 1.19.0 | 2017 July 20 | | 2017 November 14 +| Firefox 58 | Rust 1.21.0 | 1.21.0 | 2017 October 12 | | 2018 January 16 +| Firefox 59 | Rust 1.22.1 | 1.22.1 | 2017 November 23 | | 2018 March 13 +| Firefox 60 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 May 9 +| Firefox 61 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 June 26 +| Firefox 62 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 September 5 +| Firefox 63 | Rust 1.28.0 | 1.28.0 | 2018 August 2 | | 2018 October 23 +| Firefox 64 | Rust 1.29.2 | 1.29.0 | 2018 September 13 | 2018 October 15 | 2018 December 11 +| Firefox 65 | Rust 1.30.0 | 1.30.0 | 2018 October 25 | 2018 December 3 | 2019 January 29 +| Firefox 66 | Rust 1.31.0 | 1.31.0 | 2018 December 6 | 2019 January 21 | 2019 March 19 +| Firefox 67 | Rust 1.32.0 | 1.32.0 | 2019 January 17 | 2019 March 11 | 2019 May 21 +| Firefox 68 | Rust 1.34.0 | 1.34.0 | 2019 April 11 | 2019 May 13 | 2019 July 9 +| Firefox 69 | Rust 1.35.0 | 1.35.0 | 2019 May 23 | 2019 July 1 | 2019 September 3 +| Firefox 70 | Rust 1.37.0 | 1.36.0 | 2019 July 4 | 2019 August 26 | 2019 October 22 +| Firefox 71 | Rust 1.37.0 | 1.37.0 | 2019 August 15 | 2019 October 14 | 2019 December 3 +| Firefox 72 | Rust 1.38.0 | 1.37.0 | 2019 August 15 | 2019 November 25 | 2020 January 7 +| Firefox 73 | Rust 1.39.0 | 1.39.0 | 2019 November 7 | 2020 January 1 | 2020 February 11 +| Firefox 74 | Rust 1.39.0 | 1.39.0 | 2019 November 7 | 2020 February 6 | 2020 March 10 +| Firefox 75 | Rust 1.41.0 | 1.41.0 | 2020 January 30 | 2020 March 5 | 2020 April 7 +| Firefox 76 | Rust 1.41.0 | 1.41.0 | 2020 January 30 | 2020 April 2 | 2020 May 5 +| Firefox 77 | Rust 1.41.1 | 1.41.0 | 2020 January 30 | 2020 April 30 | 2020 June 2 +| Firefox 78 | Rust 1.43.0 | 1.41.0 | 2020 April 23 | 2020 May 28 | 2020 June 30 +| Firefox 79 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 June 26 | 2020 July 28 +| Firefox 80 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 July 23 | 2020 August 25 +| Firefox 81 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 August 20 | 2020 September 22 +| Firefox 82 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 September 17 | 2020 October 20 +| Firefox 83 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 October 15 | 2020 November 17 +| Firefox 84 | Rust 1.47.0 | 1.43.0 | 2020 October 8 | 2020 November 12 | 2020 December 15 +| Firefox 85 | Rust 1.48.0 | 1.47.0 | 2020 November 19 | 2020 December 10 | 2021 January 26 +| Firefox 86 | Rust 1.49.0 | 1.47.0 | 2020 December 31 | 2021 January 21 | 2021 February 23 +| Firefox 87 | Rust 1.50.0 | 1.47.0 | 2021 February 11 | 2021 February 18 | 2021 March 23 +| Firefox 88 | Rust 1.50.0 | 1.47.0 | 2021 February 11 | 2021 March 18 | 2021 April 19 +| Firefox 89 | Rust 1.51.0 | 1.47.0 | 2021 March 25 | 2021 April 15 | 2021 June 1 +| Firefox 90 | Rust 1.52.0 | 1.47.0 | 2021 May 6 | 2021 May 27 | 2021 June 29 +| Firefox 91 | Rust 1.53.0 | 1.51.0 | 2021 June 17 | 2021 July 8 | 2021 August 10 +| Firefox 92 | Rust 1.54.0 | 1.51.0 | 2021 July 29 | 2021 August 5 | 2021 September 7 +| Firefox 93 | Rust 1.54.0 | 1.51.0 | 2021 July 29 | 2021 September 2 | 2021 October 5 +| Firefox 94 | Rust 1.55.0 | 1.53.0 | 2021 September 9 | 2021 September 30 | 2021 November 2 +| Firefox 95 | Rust 1.56.0 | 1.53.0 | 2021 October 21 | 2021 October 28 | 2021 December 7 +| Firefox 96 | Rust 1.57.0 | 1.53.0 | 2021 December 2 | 2021 December 2 | 2022 January 11 +| Firefox 97 | Rust 1.57.0 | 1.57.0 | 2021 December 2 | 2022 January 6 | 2022 February 8 +| Firefox 98 | Rust 1.58.0 | 1.57.0 | 2022 January 13 | 2022 February 2 | 2022 March 8 +| Firefox 99 | Rust 1.59.0 | 1.57.0 | 2022 February 24 | 2022 March 3 | 2022 April 5 +| Firefox 100 | Rust 1.59.0 | 1.57.0 | 2022 February 24 | 2022 March 31 | 2022 May 3 +| Firefox 101 | Rust 1.60.0 | 1.59.0 | 2022 April 7 | 2022 April 28 | 2022 May 31 +| Firefox 102 | Rust 1.60.0 | 1.59.0 | 2022 April 7 | 2022 May 26 | 2022 June 28 +| Firefox 103 | Rust 1.61.0 | 1.59.0 | 2022 May 19 | 2022 June 23 | 2022 July 27 +| Firefox 104 | Rust 1.62.0 | 1.59.0 | 2022 June 30 | 2022 July 21 | 2022 August 23 +| Firefox 105 | Rust 1.63.0 | 1.61.0 | 2022 August 11 | 2022 August 18 | 2022 September 20 +| Firefox 106 | Rust 1.63.0 | 1.61.0 | 2022 August 11 | 2022 September 15 | 2022 October 18 +| Firefox 107 | Rust 1.64.0 | 1.61.0 | 2022 September 22 | 2022 October 13 | 2022 November 15 +| Firefox 108 | Rust 1.65.0 | 1.63.0 | 2022 November 3 | 2022 November 10 | 2022 December 13 +| Firefox 109 | Rust 1.65.0 | 1.63.0 | 2022 November 3 | 2022 December 8 | 2023 January 17 +| Firefox 110 | Rust 1.66.0 | 1.65.0 | 2022 December 15 | 2023 January 12 | 2023 February 14 +| Firefox 111 | Rust 1.67.0 | 1.65.0 | 2023 January 26 | 2023 February 9 | 2023 March 14 +| Firefox 112 | Rust 1.67.0 | 1.65.0 | 2023 January 26 | 2023 March 9 | 2023 April 11 +| Firefox 113 | Rust 1.68.0 | 1.65.0 | 2023 March 9 | 2023 April 6 | 2023 May 9 +| Firefox 114 | Rust 1.69.0 | 1.65.0 | 2023 April 20 | 2023 May 4 | 2023 June 6 +| Firefox 115 | Rust 1.69.0 | 1.66.0 | 2023 April 20 | 2023 June 1 | 2023 July 4 +| Firefox 116 | Rust 1.69.0 | 1.66.0 | 2023 April 20 | 2023 June 29 | 2023 August 1 +| Firefox 117 | Rust 1.71.0 | 1.66.0 | 2023 July 13 | 2023 July 27 | 2023 August 29 +| Firefox 118 | Rust 1.71.0 | 1.66.0 | 2023 July 13 | 2023 August 24 | 2023 September 26 +| Firefox 119 | Rust 1.72.0 | 1.66.0 | 2023 August 24 | 2023 September 21 | 2023 October 24 +| Firefox 120 | Rust 1.72.0 | 1.70.0 | 2023 October 4 | 2023 October 19 | 2023 November 21 +| Firefox 121 | Rust 1.73.0 | 1.70.0 | 2023 October 4 | 2023 November 16 | 2023 December 19 +| Firefox 122 | Rust 1.74.0 | 1.70.0 | 2023 November 16 | 2023 December 14 | 2024 January 23 +| Firefox 123 | Rust 1.75.0 | 1.70.0 | 2023 December 28 | 2024 January 11 | 2024 February 20 +| **Estimated** | +| Firefox 124 | Rust 1.76.0 | ? | 2023 February 8 | 2024 February 15 | 2024 March 19 +| Firefox 125 | Rust 1.76.0 | ? | 2023 February 8 | 2024 March 14 | 2024 April 16 +| Firefox 126 | Rust 1.77.0 | ? | 2023 March 21 | 2024 April 19 | 2024 May 14 +| Firefox 127 | Rust 1.78.0 | ? | 2023 May 2 | 2024 May 9 | 2024 June 11 +| Firefox 128 | Rust 1.78.0 | ? | 2023 May 2 | 2024 June 6 | 2024 July 9 +| Firefox 129 | Rust 1.79.0 | ? | 2023 June 13 | 2024 July 4 | 2024 August 6 +| Firefox 130 | Rust 1.80.0 | ? | 2023 July 25 | 2024 August 1 | 2024 September 3 |