Hygienize macros in the standard library by petrochenkov · Pull Request #61629 · rust-lang/rust

petrochenkov · 2019-06-07T18:09:51Z

Same as #55597, but for all macros in the standard library.
Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site.
Technically this is a breaking change, so crater run would probably be useful.

One exception that is not hygienized is calls to panic!(...).
Macros defined in libcore do not want to call core::panic.
What they really want to call is either std::panic or core::panic depending on no_std settings.
EDIT: After some thought, recursive calls to panic from panic itself probably do want to use $crate (UPDATE: done).

Calling std::panic from macros defined in std and "whatever panic is in scope" from macros defined in libcore is probably even worse than always calling "whatever panic is in scope", so I kept the existing code.

The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to std::panic or core::panic using compiler magic.
Then standard library macros could delegate to this built-in macro.
The macro could be named panic too, that would fix#61567.
(This PR doesn't do that.)

cc #56389
cc #61567
Fixes#61699
r? @alexcrichton

petrochenkov · 2019-06-07T18:10:26Z

@bors try

bors · 2019-06-07T18:10:37Z

⌛ Trying commit b5e00d8122499c60159d3e0e54017ce8bbc35cc1 with merge e212b7d492c96d3837691ba29d32d5f468933fb8...

bors · 2019-06-07T20:29:25Z

☀️ Try build successful - checks-travis
Build commit: e212b7d492c96d3837691ba29d32d5f468933fb8

petrochenkov · 2019-06-07T20:31:37Z

@craterbot run

craterbot · 2019-06-07T20:31:39Z

👌 Experiment pr-61629 created and queued.
🤖 Automatically detected try build e212b7d492c96d3837691ba29d32d5f468933fb8
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2019-06-07T20:31:42Z

🚧 Experiment pr-61629 is now running on agent aws-1.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

emilyalbini · 2019-06-08T17:37:20Z

@petrochenkov wait, does this need to be a cargo test run?

petrochenkov · 2019-06-08T19:06:54Z

@pietroalbini
Yes.
The idea is that user code could previously shadow standard macros with its own macros with the same interface but different behavior.
This PR removes that possibility thus changing runtime behavior.

matklad · 2019-06-09T10:15:16Z

Can this replace __rustc_unstable_column with crate::column as well?

https://github.com/rust-lang/rust/blob/b5e00d8122499c60159d3e0e54017ce8bbc35cc1/src/libcore/macros.rs#L12

petrochenkov · 2019-06-09T10:54:05Z

@matklad
column is a built-in macro, not standard library macro, so $crate::column won't work.

To call built-in macros reliably with $crate::mac!(...) we need to reexport them from the standard library first.
With 2018 edition and uniform paths it is generally possible, but there's a bug preventing reexports of built-in macros specifically.

craterbot · 2019-06-12T13:55:57Z

🎉 Experiment pr-61629 is completed!
📊 22 regressed and 11 fixed (60951 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

alexcrichton · 2019-06-12T16:54:02Z

This is looking good to me, and the crate run there looks all largely spurious to me, so I think we could probably go ahead and land this?

petrochenkov · 2019-06-12T17:12:08Z

Rebased/squashed.

Recursive calls from panic to itself are also hygienized.

alexcrichton · 2019-06-12T19:32:29Z

@bors: r+

bors · 2019-06-12T19:32:30Z

📌 Commit eb09daa has been approved by alexcrichton

Centril · 2019-06-12T19:48:14Z

@bors rollup

@alexcrichton

Hygienize macros in the standard library Same as rust-lang#55597, but for all macros in the standard library. Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site. Technically this is a breaking change, so crater run would probably be useful. --- One exception that is not hygienized is calls to `panic!(...)`. Macros defined in libcore do not want to call `core::panic`. What they really want to call is either `std::panic` or `core::panic` depending on `no_std` settings. EDIT: After some thought, recursive calls to `panic` from `panic` itself probably do want to use `$crate` (UPDATE: done). Calling `std::panic` from macros defined in std and "whatever `panic` is in scope" from macros defined in libcore is probably even worse than always calling "whatever `panic` is in scope", so I kept the existing code. The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to `std::panic` or `core::panic` using compiler magic. Then standard library macros could delegate to this built-in macro. The macro could be named `panic` too, that would fixrust-lang#61567. (This PR doesn't do that.) --- cc rust-lang#56389 cc rust-lang#61567Fixesrust-lang#61699 r? @alexcrichton

@alexcrichton

Hygienize macros in the standard library Same as rust-lang#55597, but for all macros in the standard library. Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site. Technically this is a breaking change, so crater run would probably be useful. --- One exception that is not hygienized is calls to `panic!(...)`. Macros defined in libcore do not want to call `core::panic`. What they really want to call is either `std::panic` or `core::panic` depending on `no_std` settings. EDIT: After some thought, recursive calls to `panic` from `panic` itself probably do want to use `$crate` (UPDATE: done). Calling `std::panic` from macros defined in std and "whatever `panic` is in scope" from macros defined in libcore is probably even worse than always calling "whatever `panic` is in scope", so I kept the existing code. The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to `std::panic` or `core::panic` using compiler magic. Then standard library macros could delegate to this built-in macro. The macro could be named `panic` too, that would fixrust-lang#61567. (This PR doesn't do that.) --- cc rust-lang#56389 cc rust-lang#61567Fixesrust-lang#61699 r? @alexcrichton

@ghost

Rollup of 9 pull requests Successful merges: - #60376 (Stabilize Option::xor) - #61398 (Stabilize copy_within) - #61629 (Hygienize macros in the standard library) - #61675 (Include frame pointer for bare metal RISC-V targets) - #61750 (Fix x.py install) - #61761 (Add an alias for x86_64-sun-solaris target tuple) - #61762 (rustbuild: fix libtest_stamp) - #61763 (ci: fix ci stats upload condition) - #61776 (Fix typos in error_codes) Failed merges: r? @ghost

pnkfelix · 2019-06-20T14:59:58Z

discussed at T-compiler meeting. Accepting for backport to beta.

@ghost

[beta] Rollup backports Rolled up: * [beta] Comment out dev key #61700 Cherry picked: * Dont ICE on an attempt to use GAT without feature gate #61118 * Fix cfg(test) build for x86_64-fortanix-unknown-sgx #61503 * Handle index out of bound errors during const eval without panic #61598 * Hygienize macros in the standard library #61629 * Fix ICE involving mut references #61947 * rustc_typeck: correctly compute `Substs` for `Res::SelfCtor`. #61896 * Revert "Set test flag when rustdoc is running with --test option" #61199 * create a "provisional cache" to restore performance in the case of cycles #61754 r? @ghost

@alexcrichton

Hygienize use of built-in macros in the standard library Same as rust-lang#61629, but for built-in macros. Closesrust-lang#48781 r? @alexcrichton

rust-highfive assigned alexcrichton Jun 7, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 7, 2019

This was referenced Jun 7, 2019
assert! in edition 2018 has a non-hygienic use of panic! #56389
Closed
regression: assert_eq cannot find panic with no_implicit_prelude #61567
Closed

craterbot added S-waiting-on-crater Status: Waiting on a crater run to be completed. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 7, 2019

petrochenkov mentioned this pull request Jun 9, 2019
strange scoping issue when trying to use alloc::vec![] #61699
Closed

craterbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels Jun 12, 2019

petrochenkov force-pushed the stdmac branch from b5e00d8 to 8fc9d13Compare June 12, 2019 17:11

Hygienize macros in the standard library
eb09daa

petrochenkov force-pushed the stdmac branch from 8fc9d13 to eb09daaCompare June 12, 2019 17:27

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 12, 2019

Centril mentioned this pull request Jun 12, 2019
Rollup of 10 pull requests #61783
Closed

Centril mentioned this pull request Jun 12, 2019
Rollup of 9 pull requests #61789
Merged

bors merged commit eb09daa into rust-lang:masterJun 13, 2019

petrochenkov deleted the stdmac branch June 13, 2019 07:26

petrochenkov mentioned this pull request Jun 19, 2019
resolve: Temporarily make panic available with no_implicit_prelude#61971
Closed

pnkfelix added beta-nominated Nominated for backporting to the compiler in the beta channel. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 20, 2019

pnkfelix added the beta-accepted Accepted for backporting to the compiler in the beta channel. label Jun 20, 2019

petrochenkov mentioned this pull request Jun 20, 2019
[experiment] Introduce a reliable way to refer to the standard library and use it for calling panic#62002
Closed

emilyalbini mentioned this pull request Jun 22, 2019
[beta] Rollup backports #62065
Merged

emilyalbini removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Jun 22, 2019

petrochenkov mentioned this pull request Jul 6, 2019
Define built-in macros through libcore #62086
Merged

petrochenkov mentioned this pull request Aug 15, 2019
Hygienize use of built-in macros in the standard library #63613
Merged

petrochenkov mentioned this pull request Oct 25, 2020
Qualify panic! as core::panic! in non-built-in core macros #78343
Merged

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