Clarify that safe extern items do not require unsafe #1970
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This clarifies items.extern.fn-safety that it only applies to unsafe items. `safe` items do not require an unsafe context. I think this was just missed in rust-lang#1536.
This rule applies to both fn and static, so remove the "fn" part of the rule name.
In light of `unsafe extern`, we need to note that only unsafe extern
statics need `unsafe { .. }` and to clarify that not all foreign
functions are necessarily unsafe to call.
Co-authored-by: ehuss
Co-authored-by: ehuss
In light of `unsafe extern`, we need to note that this is another position that `unsafe` is allowed. While we're here, let's make some further revisions to clean up the start of this chapter, including separating off into a rule these allowed positions. Co-authored-by: ehuss
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Update books ## rust-lang/nomicon 1 commits in 3ff384320598bbe8d8cfe5cb8f18f78a3a3e6b15..57ed4473660565d9357fcae176b358d7e8724ebf 2025-08-18 17:31:07 UTC to 2025-08-18 17:31:07 UTC - Fix unknown field `author` error when building the book (rust-lang/nomicon#500) ## rust-lang/reference 11 commits in 59b8af811886313577615c2cf0e045f01faed88b..89f67b3c1b904cbcd9ed55e443d6fc67c8ca2769 2025-08-22 07:16:52 UTC to 2025-08-14 18:42:19 UTC - Update `instruction_set` to use the attribute template (rust-lang/reference#1912) - Update `debugger_visualizer` to use the attribute template (rust-lang/reference#1922) - Update `collapse_debuginfo` to use the attribute template (rust-lang/reference#1923) - Clarify operand evaluation order in compound assignment with primitiv… (rust-lang/reference#1941) - Switch to using native mdbook fragment redirects (rust-lang/reference#1965) - Fix traits implemented for function items (rust-lang/reference#1969) - Clarify that safe extern items do not require unsafe (rust-lang/reference#1970) - Update `type_length_limit` to use the attribute template (rust-lang/reference#1917) - Add missing rule identifier for const outer generics (rust-lang/reference#1962) - Fix indentation of static path restriction text (rust-lang/reference#1961) - Add doc for `sse4a` and `tbm` (rust-lang/reference#1949) ## rust-lang/rust-by-example 2 commits in adc1f3b9012ad3255eea2054ca30596a953d053d..ad27f82c18464525c761a4a8db2e01785da59e1f 2025-08-20 23:50:16 UTC to 2025-08-13 21:41:46 UTC - Support building books using mdbook in main (v0.5.x) (rust-lang/rust-by-example#1952) - Improve the hints in `fmt` (1.2.3. Formatting); mention type casting (rust-lang/rust-by-example#1951)
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Update books ## rust-lang/nomicon 1 commits in 3ff384320598bbe8d8cfe5cb8f18f78a3a3e6b15..57ed4473660565d9357fcae176b358d7e8724ebf 2025-08-18 17:31:07 UTC to 2025-08-18 17:31:07 UTC - Fix unknown field `author` error when building the book (rust-lang/nomicon#500) ## rust-lang/reference 11 commits in 59b8af811886313577615c2cf0e045f01faed88b..89f67b3c1b904cbcd9ed55e443d6fc67c8ca2769 2025-08-22 07:16:52 UTC to 2025-08-14 18:42:19 UTC - Update `instruction_set` to use the attribute template (rust-lang/reference#1912) - Update `debugger_visualizer` to use the attribute template (rust-lang/reference#1922) - Update `collapse_debuginfo` to use the attribute template (rust-lang/reference#1923) - Clarify operand evaluation order in compound assignment with primitiv… (rust-lang/reference#1941) - Switch to using native mdbook fragment redirects (rust-lang/reference#1965) - Fix traits implemented for function items (rust-lang/reference#1969) - Clarify that safe extern items do not require unsafe (rust-lang/reference#1970) - Update `type_length_limit` to use the attribute template (rust-lang/reference#1917) - Add missing rule identifier for const outer generics (rust-lang/reference#1962) - Fix indentation of static path restriction text (rust-lang/reference#1961) - Add doc for `sse4a` and `tbm` (rust-lang/reference#1949) ## rust-lang/rust-by-example 2 commits in adc1f3b9012ad3255eea2054ca30596a953d053d..ad27f82c18464525c761a4a8db2e01785da59e1f 2025-08-20 23:50:16 UTC to 2025-08-13 21:41:46 UTC - Support building books using mdbook in main (v0.5.x) (rust-lang/rust-by-example#1952) - Improve the hints in `fmt` (1.2.3. Formatting); mention type casting (rust-lang/rust-by-example#1951)
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Update books ## rust-lang/nomicon 1 commits in 3ff384320598bbe8d8cfe5cb8f18f78a3a3e6b15..57ed4473660565d9357fcae176b358d7e8724ebf 2025-08-18 17:31:07 UTC to 2025-08-18 17:31:07 UTC - Fix unknown field `author` error when building the book (rust-lang/nomicon#500) ## rust-lang/reference 11 commits in 59b8af811886313577615c2cf0e045f01faed88b..89f67b3c1b904cbcd9ed55e443d6fc67c8ca2769 2025-08-22 07:16:52 UTC to 2025-08-14 18:42:19 UTC - Update `instruction_set` to use the attribute template (rust-lang/reference#1912) - Update `debugger_visualizer` to use the attribute template (rust-lang/reference#1922) - Update `collapse_debuginfo` to use the attribute template (rust-lang/reference#1923) - Clarify operand evaluation order in compound assignment with primitiv… (rust-lang/reference#1941) - Switch to using native mdbook fragment redirects (rust-lang/reference#1965) - Fix traits implemented for function items (rust-lang/reference#1969) - Clarify that safe extern items do not require unsafe (rust-lang/reference#1970) - Update `type_length_limit` to use the attribute template (rust-lang/reference#1917) - Add missing rule identifier for const outer generics (rust-lang/reference#1962) - Fix indentation of static path restriction text (rust-lang/reference#1961) - Add doc for `sse4a` and `tbm` (rust-lang/reference#1949) ## rust-lang/rust-by-example 2 commits in adc1f3b9012ad3255eea2054ca30596a953d053d..ad27f82c18464525c761a4a8db2e01785da59e1f 2025-08-20 23:50:16 UTC to 2025-08-13 21:41:46 UTC - Support building books using mdbook in main (v0.5.x) (rust-lang/rust-by-example#1952) - Improve the hints in `fmt` (1.2.3. Formatting); mention type casting (rust-lang/rust-by-example#1951)
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This clarifies items.extern.fn-safety that it only applies to unsafe items.
safeitems do not require an unsafe context.I think this was just missed in #1536.