Avoid specifying "last import wins" for MBEs #2057
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| > [!NOTE] | ||
| > `rustc` currently prefers the last macro in case of conflict. Don't rely on this. This behavior is unusual, as imports in Rust are generally order-independent. This behavior of `macro_use` may change in the future. |
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If there's a good issue to cite for this, we can cite it here.
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I've opened rust-lang/rust#148025 for this.
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Thanks. Added it here.
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Currently, for `macro_use`, the last macro imported wins. This may be something that we consider to be a bug. Rather than documenting this normatively, then, let's stay normatively silent on that behavior and document the details of the situation with `rustc` in an admonition.
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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Update books ## rust-lang/book 6 commits in af415fc6c8a6823dfb4595074f27d5a3e9e2fe49..f660f341887c8bbcd6c24fbfdf5d2a262f523965 2025-10-28 01:41:51 UTC to 2025-10-24 15:39:51 UTC - Update to Rust 1.90 (rust-lang/book#4545) - Update to Rust 1.89 (rust-lang/book#4544) - Update to Rust 1.88 (rust-lang/book#4543) - Update to Rust 1.87 (rust-lang/book#4542) - Update to Rust 1.86 (rust-lang/book#4541) - Remove unused subheadings (rust-lang/book#4538) ## rust-lang/edition-guide 1 commits in e2ed891f00361efc26616d82590b1c85d7a8920e..5c621253d8f2a5a4adb64a6365905db67dffe3a2 2025-10-23 14:13:01 UTC to 2025-10-23 14:13:01 UTC - Add back the link for never_type_fallback_flowing_into_unsafe (rust-lang/edition-guide#378) ## rust-lang/reference 12 commits in 752eab01cebdd6a2d90b53087298844c251859a1..e122eefff3fef362eb7e0c08fb7ffbf5f9461905 2025-10-28 20:52:27 UTC to 2025-10-21 19:42:06 UTC - Remove custom redirect scripts (rust-lang/reference#2065) - Avoid specifying "last import wins" for MBEs (rust-lang/reference#2057) - Add caveats about mutable references in consts (rust-lang/reference#2058) - Move punctuation index to an appendix, and expand for other syntaxes (rust-lang/reference#2061) - Use American spelling for "labeled" (rust-lang/reference#2066) - Remove rules from names intro (rust-lang/reference#2060) - Minor adjustments to inner/outer attribute definitions (rust-lang/reference#2059) - Change underscore to be a keyword (rust-lang/reference#2049) - Update `proc_macro_attribute` to use the attribute template (rust-lang/reference#1889) - Update `proc_macro` to use the attribute template (rust-lang/reference#1887) - Update `macro_use` to use the attribute template (rust-lang/reference#1886) - Update `macro_export` to use the attribute template (rust-lang/reference#1885) ## rust-lang/rust-by-example 7 commits in 2c9b490d70e535cf166bf17feba59e594579843f..160e6bbca70b0c01aa4de88d19db7fc5ff8447c3 2025-11-03 12:26:45 UTC to 2025-10-22 13:19:06 UTC - Fix typos in flow_control/match/binding (rust-lang/rust-by-example#1971) - add clarification on overflowing_literals lint (rust-lang/rust-by-example#1970) - Update enum_use.md (rust-lang/rust-by-example#1960) - Remove weird extra spaces in code (rust-lang/rust-by-example#1962) - Include a link to The Rust Reference in flow_control/match/destructuring (rust-lang/rust-by-example#1963) - Add an example showing pattern binding when matching several values in a match arm (rust-lang/rust-by-example#1966) - Fix typo in linked list length calculation comment (rust-lang/rust-by-example#1968)
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Update books ## rust-lang/book 6 commits in af415fc6c8a6823dfb4595074f27d5a3e9e2fe49..f660f341887c8bbcd6c24fbfdf5d2a262f523965 2025-10-28 01:41:51 UTC to 2025-10-24 15:39:51 UTC - Update to Rust 1.90 (rust-lang/book#4545) - Update to Rust 1.89 (rust-lang/book#4544) - Update to Rust 1.88 (rust-lang/book#4543) - Update to Rust 1.87 (rust-lang/book#4542) - Update to Rust 1.86 (rust-lang/book#4541) - Remove unused subheadings (rust-lang/book#4538) ## rust-lang/edition-guide 1 commits in e2ed891f00361efc26616d82590b1c85d7a8920e..5c621253d8f2a5a4adb64a6365905db67dffe3a2 2025-10-23 14:13:01 UTC to 2025-10-23 14:13:01 UTC - Add back the link for never_type_fallback_flowing_into_unsafe (rust-lang/edition-guide#378) ## rust-lang/reference 12 commits in 752eab01cebdd6a2d90b53087298844c251859a1..e122eefff3fef362eb7e0c08fb7ffbf5f9461905 2025-10-28 20:52:27 UTC to 2025-10-21 19:42:06 UTC - Remove custom redirect scripts (rust-lang/reference#2065) - Avoid specifying "last import wins" for MBEs (rust-lang/reference#2057) - Add caveats about mutable references in consts (rust-lang/reference#2058) - Move punctuation index to an appendix, and expand for other syntaxes (rust-lang/reference#2061) - Use American spelling for "labeled" (rust-lang/reference#2066) - Remove rules from names intro (rust-lang/reference#2060) - Minor adjustments to inner/outer attribute definitions (rust-lang/reference#2059) - Change underscore to be a keyword (rust-lang/reference#2049) - Update `proc_macro_attribute` to use the attribute template (rust-lang/reference#1889) - Update `proc_macro` to use the attribute template (rust-lang/reference#1887) - Update `macro_use` to use the attribute template (rust-lang/reference#1886) - Update `macro_export` to use the attribute template (rust-lang/reference#1885) ## rust-lang/rust-by-example 7 commits in 2c9b490d70e535cf166bf17feba59e594579843f..160e6bbca70b0c01aa4de88d19db7fc5ff8447c3 2025-11-03 12:26:45 UTC to 2025-10-22 13:19:06 UTC - Fix typos in flow_control/match/binding (rust-lang/rust-by-example#1971) - add clarification on overflowing_literals lint (rust-lang/rust-by-example#1970) - Update enum_use.md (rust-lang/rust-by-example#1960) - Remove weird extra spaces in code (rust-lang/rust-by-example#1962) - Include a link to The Rust Reference in flow_control/match/destructuring (rust-lang/rust-by-example#1963) - Add an example showing pattern binding when matching several values in a match arm (rust-lang/rust-by-example#1966) - Fix typo in linked list length calculation comment (rust-lang/rust-by-example#1968)
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Nov 4, 2025
Update books ## rust-lang/book 6 commits in af415fc6c8a6823dfb4595074f27d5a3e9e2fe49..f660f341887c8bbcd6c24fbfdf5d2a262f523965 2025-10-28 01:41:51 UTC to 2025-10-24 15:39:51 UTC - Update to Rust 1.90 (rust-lang/book#4545) - Update to Rust 1.89 (rust-lang/book#4544) - Update to Rust 1.88 (rust-lang/book#4543) - Update to Rust 1.87 (rust-lang/book#4542) - Update to Rust 1.86 (rust-lang/book#4541) - Remove unused subheadings (rust-lang/book#4538) ## rust-lang/edition-guide 1 commits in e2ed891f00361efc26616d82590b1c85d7a8920e..5c621253d8f2a5a4adb64a6365905db67dffe3a2 2025-10-23 14:13:01 UTC to 2025-10-23 14:13:01 UTC - Add back the link for never_type_fallback_flowing_into_unsafe (rust-lang/edition-guide#378) ## rust-lang/reference 12 commits in 752eab01cebdd6a2d90b53087298844c251859a1..e122eefff3fef362eb7e0c08fb7ffbf5f9461905 2025-10-28 20:52:27 UTC to 2025-10-21 19:42:06 UTC - Remove custom redirect scripts (rust-lang/reference#2065) - Avoid specifying "last import wins" for MBEs (rust-lang/reference#2057) - Add caveats about mutable references in consts (rust-lang/reference#2058) - Move punctuation index to an appendix, and expand for other syntaxes (rust-lang/reference#2061) - Use American spelling for "labeled" (rust-lang/reference#2066) - Remove rules from names intro (rust-lang/reference#2060) - Minor adjustments to inner/outer attribute definitions (rust-lang/reference#2059) - Change underscore to be a keyword (rust-lang/reference#2049) - Update `proc_macro_attribute` to use the attribute template (rust-lang/reference#1889) - Update `proc_macro` to use the attribute template (rust-lang/reference#1887) - Update `macro_use` to use the attribute template (rust-lang/reference#1886) - Update `macro_export` to use the attribute template (rust-lang/reference#1885) ## rust-lang/rust-by-example 7 commits in 2c9b490d70e535cf166bf17feba59e594579843f..160e6bbca70b0c01aa4de88d19db7fc5ff8447c3 2025-11-03 12:26:45 UTC to 2025-10-22 13:19:06 UTC - Fix typos in flow_control/match/binding (rust-lang/rust-by-example#1971) - add clarification on overflowing_literals lint (rust-lang/rust-by-example#1970) - Update enum_use.md (rust-lang/rust-by-example#1960) - Remove weird extra spaces in code (rust-lang/rust-by-example#1962) - Include a link to The Rust Reference in flow_control/match/destructuring (rust-lang/rust-by-example#1963) - Add an example showing pattern binding when matching several values in a match arm (rust-lang/rust-by-example#1966) - Fix typo in linked list length calculation comment (rust-lang/rust-by-example#1968)
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Rollup merge of #148448 - rustbot:docs-update, r=ehuss Update books ## rust-lang/book 6 commits in af415fc6c8a6823dfb4595074f27d5a3e9e2fe49..f660f341887c8bbcd6c24fbfdf5d2a262f523965 2025-10-28 01:41:51 UTC to 2025-10-24 15:39:51 UTC - Update to Rust 1.90 (rust-lang/book#4545) - Update to Rust 1.89 (rust-lang/book#4544) - Update to Rust 1.88 (rust-lang/book#4543) - Update to Rust 1.87 (rust-lang/book#4542) - Update to Rust 1.86 (rust-lang/book#4541) - Remove unused subheadings (rust-lang/book#4538) ## rust-lang/edition-guide 1 commits in e2ed891f00361efc26616d82590b1c85d7a8920e..5c621253d8f2a5a4adb64a6365905db67dffe3a2 2025-10-23 14:13:01 UTC to 2025-10-23 14:13:01 UTC - Add back the link for never_type_fallback_flowing_into_unsafe (rust-lang/edition-guide#378) ## rust-lang/reference 12 commits in 752eab01cebdd6a2d90b53087298844c251859a1..e122eefff3fef362eb7e0c08fb7ffbf5f9461905 2025-10-28 20:52:27 UTC to 2025-10-21 19:42:06 UTC - Remove custom redirect scripts (rust-lang/reference#2065) - Avoid specifying "last import wins" for MBEs (rust-lang/reference#2057) - Add caveats about mutable references in consts (rust-lang/reference#2058) - Move punctuation index to an appendix, and expand for other syntaxes (rust-lang/reference#2061) - Use American spelling for "labeled" (rust-lang/reference#2066) - Remove rules from names intro (rust-lang/reference#2060) - Minor adjustments to inner/outer attribute definitions (rust-lang/reference#2059) - Change underscore to be a keyword (rust-lang/reference#2049) - Update `proc_macro_attribute` to use the attribute template (rust-lang/reference#1889) - Update `proc_macro` to use the attribute template (rust-lang/reference#1887) - Update `macro_use` to use the attribute template (rust-lang/reference#1886) - Update `macro_export` to use the attribute template (rust-lang/reference#1885) ## rust-lang/rust-by-example 7 commits in 2c9b490d70e535cf166bf17feba59e594579843f..160e6bbca70b0c01aa4de88d19db7fc5ff8447c3 2025-11-03 12:26:45 UTC to 2025-10-22 13:19:06 UTC - Fix typos in flow_control/match/binding (rust-lang/rust-by-example#1971) - add clarification on overflowing_literals lint (rust-lang/rust-by-example#1970) - Update enum_use.md (rust-lang/rust-by-example#1960) - Remove weird extra spaces in code (rust-lang/rust-by-example#1962) - Include a link to The Rust Reference in flow_control/match/destructuring (rust-lang/rust-by-example#1963) - Add an example showing pattern binding when matching several values in a match arm (rust-lang/rust-by-example#1966) - Fix typo in linked list length calculation comment (rust-lang/rust-by-example#1968)
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Currently, for
macro_use, the last macro imported wins. This may be something that we consider to be a bug. Rather than documenting this normatively, then, let's stay normatively silent on that behavior and document the details of the situation withrustcin an admonition.cc @ehuss @petrochenkov #1886 (comment)