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1 # Rust Update Policy
3 We document here the decision making and planning around when we update the
4 Rust toolchains used and required to build Firefox.
6 This allows contributors to know when new features will be usable, and
7 downstream packagers to know what toolchain will be required for each Firefox
8 release. Both benefit from the predictability of a schedule.
10 ## Policy
12 ### Official builds
14 _We ship official stable Firefox with a stable Rust._
16 As a general rule, we update the Rust version used to build Firefox Nightly
17 soon after its release, unless it's less than 7 days away from a soft-freeze,
18 in which case we wait for the next Nightly train.
20 We don't upgrade the Rust version in the beta or release branches of Firefox.
22 The following exceptions apply:
24 - We may use a Rust version from the Rust beta or nightly channels for new
25 platforms (e.g. we did so for Android, arm64 Windows and arm64 macOS), and
26 later upgrade when that Rust version becomes stable (we may even do so on the
27 Firefox beta branch).
29 - We may skip the update (or backout the update) if major problems are
30 encountered (typically, we've had to do so because of build problems, crash
31 reporting bustage, or performance issues).
33 ### Developer builds
35 _Local developer builds use whatever Rust toolchain is available on the
36 system._
38 Someone building Firefox can maintain the latest stable Rust with the `rustup`
39 or `mach bootstrap` tools, or try other variations.
41 ### Minimum Supported Rust Version
43 _We will update the Minimum Supported Rust Version (MSRV) when required._
45 The MSRV will generally remain unchanged, until a newer version is required
46 by some code.
48 When that happens, we'll prefer to update the MSRV to the strict minimum
49 required at that moment (e.g. if we require version 1.47.0, the currently used
50 Rust version is 1.51.0, and a crate needs 1.50.0, we'll prefer to update the
51 MSRV to 1.50.0 rather than 1.51.0).
53 The MSRV won't be updated to a version of Rust that hasn't been used for
54 Firefox Nightly for at least 14 days.
56 We expect ESR releases will keep their MSRV, so backporting security fixes may
57 require Rust compatibility work.
59 ### Rationale
61 Historically, the Rust ecosystem quickly required new features provided by new
62 Rust compilers, which made it necessary to update the minimum supported version
63 quite often, and as such, a scheduled update was deemed a better trade-off.
65 Fast-forward several years, and new Rust compiler releases more rarely sport
66 ground-breaking new features, which has reduced the necessity to update quite
67 significantly.
69 On the flip side, in some instances, we have had to stick to specific versions
70 of the Rust compiler for extended periods of time because of e.g. regressions,
71 going against the schedule.
73 ## Schedule
75 Here are the Rust versions for each Firefox version.
77 - The "Uses" column indicates the version of Rust used to build
78 releases shipped to users.
80 - The "MSRV" column indicates the minimum supported Rust version to build
81 the sources.
83 | Firefox Version | Uses | MSRV | Rust "Uses" release date | Nightly Soft Freeze | Firefox release date |
84 |-----------------|------|----------|--------------------------|---------------------|----------------------|
85 | Firefox 56 | Rust 1.19.0 | 1.17.0 | 2017 April 27 | | 2017 September 26
86 | Firefox 57 | Rust 1.19.0 | 1.19.0 | 2017 July 20 | | 2017 November 14
87 | Firefox 58 | Rust 1.21.0 | 1.21.0 | 2017 October 12 | | 2018 January 16
88 | Firefox 59 | Rust 1.22.1 | 1.22.1 | 2017 November 23 | | 2018 March 13
89 | Firefox 60 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 May 9
90 | Firefox 61 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 June 26
91 | Firefox 62 | Rust 1.24.0 | 1.24.0 | 2018 February 15 | | 2018 September 5
92 | Firefox 63 | Rust 1.28.0 | 1.28.0 | 2018 August 2 | | 2018 October 23
93 | Firefox 64 | Rust 1.29.2 | 1.29.0 | 2018 September 13 | 2018 October 15 | 2018 December 11
94 | Firefox 65 | Rust 1.30.0 | 1.30.0 | 2018 October 25 | 2018 December 3 | 2019 January 29
95 | Firefox 66 | Rust 1.31.0 | 1.31.0 | 2018 December 6 | 2019 January 21 | 2019 March 19
96 | Firefox 67 | Rust 1.32.0 | 1.32.0 | 2019 January 17 | 2019 March 11 | 2019 May 21
97 | Firefox 68 | Rust 1.34.0 | 1.34.0 | 2019 April 11 | 2019 May 13 | 2019 July 9
98 | Firefox 69 | Rust 1.35.0 | 1.35.0 | 2019 May 23 | 2019 July 1 | 2019 September 3
99 | Firefox 70 | Rust 1.37.0 | 1.36.0 | 2019 July 4 | 2019 August 26 | 2019 October 22
100 | Firefox 71 | Rust 1.37.0 | 1.37.0 | 2019 August 15 | 2019 October 14 | 2019 December 3
101 | Firefox 72 | Rust 1.38.0 | 1.37.0 | 2019 August 15 | 2019 November 25 | 2020 January 7
102 | Firefox 73 | Rust 1.39.0 | 1.39.0 | 2019 November 7 | 2020 January 1 | 2020 February 11
103 | Firefox 74 | Rust 1.39.0 | 1.39.0 | 2019 November 7 | 2020 February 6 | 2020 March 10
104 | Firefox 75 | Rust 1.41.0 | 1.41.0 | 2020 January 30 | 2020 March 5 | 2020 April 7
105 | Firefox 76 | Rust 1.41.0 | 1.41.0 | 2020 January 30 | 2020 April 2 | 2020 May 5
106 | Firefox 77 | Rust 1.41.1 | 1.41.0 | 2020 January 30 | 2020 April 30 | 2020 June 2
107 | Firefox 78 | Rust 1.43.0 | 1.41.0 | 2020 April 23 | 2020 May 28 | 2020 June 30
108 | Firefox 79 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 June 26 | 2020 July 28
109 | Firefox 80 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 July 23 | 2020 August 25
110 | Firefox 81 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 August 20 | 2020 September 22
111 | Firefox 82 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 September 17 | 2020 October 20
112 | Firefox 83 | Rust 1.43.0 | 1.43.0 | 2020 April 23 | 2020 October 15 | 2020 November 17
113 | Firefox 84 | Rust 1.47.0 | 1.43.0 | 2020 October 8 | 2020 November 12 | 2020 December 15
114 | Firefox 85 | Rust 1.48.0 | 1.47.0 | 2020 November 19 | 2020 December 10 | 2021 January 26
115 | Firefox 86 | Rust 1.49.0 | 1.47.0 | 2020 December 31 | 2021 January 21 | 2021 February 23
116 | Firefox 87 | Rust 1.50.0 | 1.47.0 | 2021 February 11 | 2021 February 18 | 2021 March 23
117 | Firefox 88 | Rust 1.50.0 | 1.47.0 | 2021 February 11 | 2021 March 18 | 2021 April 19
118 | Firefox 89 | Rust 1.51.0 | 1.47.0 | 2021 March 25 | 2021 April 15 | 2021 June 1
119 | Firefox 90 | Rust 1.52.0 | 1.47.0 | 2021 May 6 | 2021 May 27 | 2021 June 29
120 | Firefox 91 | Rust 1.53.0 | 1.51.0 | 2021 June 17 | 2021 July 8 | 2021 August 10
121 | Firefox 92 | Rust 1.54.0 | 1.51.0 | 2021 July 29 | 2021 August 5 | 2021 September 7
122 | Firefox 93 | Rust 1.54.0 | 1.51.0 | 2021 July 29 | 2021 September 2 | 2021 October 5
123 | Firefox 94 | Rust 1.55.0 | 1.53.0 | 2021 September 9 | 2021 September 30 | 2021 November 2
124 | Firefox 95 | Rust 1.56.0 | 1.53.0 | 2021 October 21 | 2021 October 28 | 2021 December 7
125 | Firefox 96 | Rust 1.57.0 | 1.53.0 | 2021 December 2 | 2021 December 2 | 2022 January 11
126 | Firefox 97 | Rust 1.57.0 | 1.57.0 | 2021 December 2 | 2022 January 6 | 2022 February 8
127 | Firefox 98 | Rust 1.58.0 | 1.57.0 | 2022 January 13 | 2022 February 2 | 2022 March 8
128 | Firefox 99 | Rust 1.59.0 | 1.57.0 | 2022 February 24 | 2022 March 3 | 2022 April 5
129 | Firefox 100 | Rust 1.59.0 | 1.57.0 | 2022 February 24 | 2022 March 31 | 2022 May 3
130 | Firefox 101 | Rust 1.60.0 | 1.59.0 | 2022 April 7 | 2022 April 28 | 2022 May 31
131 | Firefox 102 | Rust 1.60.0 | 1.59.0 | 2022 April 7 | 2022 May 26 | 2022 June 28
132 | Firefox 103 | Rust 1.61.0 | 1.59.0 | 2022 May 19 | 2022 June 23 | 2022 July 27
133 | Firefox 104 | Rust 1.62.0 | 1.59.0 | 2022 June 30 | 2022 July 21 | 2022 August 23
134 | Firefox 105 | Rust 1.63.0 | 1.61.0 | 2022 August 11 | 2022 August 18 | 2022 September 20
135 | Firefox 106 | Rust 1.63.0 | 1.61.0 | 2022 August 11 | 2022 September 15 | 2022 October 18
136 | Firefox 107 | Rust 1.64.0 | 1.61.0 | 2022 September 22 | 2022 October 13 | 2022 November 15
137 | Firefox 108 | Rust 1.65.0 | 1.63.0 | 2022 November 3 | 2022 November 10 | 2022 December 13
138 | Firefox 109 | Rust 1.65.0 | 1.63.0 | 2022 November 3 | 2022 December 8 | 2023 January 17
139 | Firefox 110 | Rust 1.66.0 | 1.65.0 | 2022 December 15 | 2023 January 12 | 2023 February 14
140 | Firefox 111 | Rust 1.67.0 | 1.65.0 | 2023 January 26 | 2023 February 9 | 2023 March 14
141 | Firefox 112 | Rust 1.67.0 | 1.65.0 | 2023 January 26 | 2023 March 9 | 2023 April 11
142 | Firefox 113 | Rust 1.68.0 | 1.65.0 | 2023 March 9 | 2023 April 6 | 2023 May 9
143 | Firefox 114 | Rust 1.69.0 | 1.65.0 | 2023 April 20 | 2023 May 4 | 2023 June 6
144 | Firefox 115 | Rust 1.69.0 | 1.66.0 | 2023 April 20 | 2023 June 1 | 2023 July 4
145 | Firefox 116 | Rust 1.69.0 | 1.66.0 | 2023 April 20 | 2023 June 29 | 2023 August 1
146 | Firefox 117 | Rust 1.71.0 | 1.66.0 | 2023 July 13 | 2023 July 27 | 2023 August 29
147 | Firefox 118 | Rust 1.71.0 | 1.66.0 | 2023 July 13 | 2023 August 24 | 2023 September 26
148 | Firefox 119 | Rust 1.72.0 | 1.66.0 | 2023 August 24 | 2023 September 21 | 2023 October 24
149 | Firefox 120 | Rust 1.72.0 | 1.70.0 | 2023 October 4 | 2023 October 19 | 2023 November 21
150 | Firefox 121 | Rust 1.73.0 | 1.70.0 | 2023 October 4 | 2023 November 16 | 2023 December 19
151 | Firefox 122 | Rust 1.74.0 | 1.70.0 | 2023 November 16 | 2023 December 14 | 2024 January 23
152 | Firefox 123 | Rust 1.75.0 | 1.70.0 | 2023 December 28 | 2024 January 11 | 2024 February 20
153 | Firefox 124 | Rust 1.76.0 | 1.70.0 | 2024 February 8 | 2024 February 15 | 2024 March 19
154 | Firefox 125 | Rust 1.76.0 | 1.74.0 | 2024 February 8 | 2024 March 14 | 2024 April 16
155 | **Estimated** |
156 | Firefox 126 | Rust 1.77.2 | ? | 2024 March 28 | 2024 April 11 | 2024 May 14
157 | Firefox 127 | Rust 1.78.0 | ? | 2024 May 2 | 2024 May 9 | 2024 June 11
158 | Firefox 128 | Rust 1.78.0 | ? | 2024 May 2 | 2024 June 6 | 2024 July 9
159 | Firefox 129 | Rust 1.79.0 | ? | 2024 June 13 | 2024 July 4 | 2024 August 6
160 | Firefox 130 | Rust 1.80.0 | ? | 2024 July 25 | 2024 August 1 | 2024 September 3
161 | Firefox 131 | Rust 1.80.0 | ? | 2024 July 25 | 2024 August 29 | 2024 October 1
162 | Firefox 132 | Rust 1.81.0 | ? | 2024 September 5 | 2024 September 26 | 2024 October 29