WIP: Gate generating `mod` items in procedural macros by alexcrichton · Pull Request #50587 · rust-lang/rust

alexcrichton · 2018-05-09T22:23:44Z

Discovered in #50504 the hygiene here is super questionable, so we'll likely want to gate this by default for procedural macros and procedural attributes for sure. This is a PR to evaluate the impact for procedural derive as well.

rust-highfive · 2018-05-09T22:23:48Z

r? @eddyb

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alexcrichton · 2018-05-09T22:23:52Z

@bors: try

alexcrichton · 2018-05-09T22:24:03Z

@rust-lang/infra, could this be queued up for a check-only crater run?

bors · 2018-05-09T22:24:04Z

⌛ Trying commit bf3a1f146ad648bca69083a52dea192ba7a65e1f with merge d8c55432067be68f5e33e1472daddd580de55bca...

alexcrichton · 2018-05-09T22:26:55Z

@bors: try

bors · 2018-05-09T22:27:05Z

⌛ Trying commit 37b3c5e with merge d5fe9545473461c4b00b487ae07543b8d8646f3c...

rust-highfive · 2018-05-09T23:48:08Z

The job x86_64-gnu-llvm-3.9 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:start:test_run-pass-fulldeps
Check compiletest suite=run-pass-fulldeps mode=run-pass (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[00:58:09] [00:58:09] running 88 tests
[00:59:50] ................................................F........F..................test [run-pass] run-pass-fulldeps/myriad-closures.rs has been running for over 60 seconds
[01:02:15] failures:
[01:02:15] [01:02:15] ---- [run-pass] run-pass-fulldeps/proc-macro/add-impl.rs stdout ----
[01:02:15] [01:02:15] [01:02:15] error: compilation failed!
[01:02:15] status: exit code: 101
[01:02:15] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/run-pass-fulldeps/proc-macro/add-impl.rs" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps" "--target=x86_64-unknown-linux-gnu" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps/proc-macro/add-impl.stage2-x86_64-unknown-linux-gnu" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps/proc-macro/add-impl.stage2-x86_64-unknown-linux-gnu.aux"
[01:02:15] ------------------------------------------
[01:02:15] [01:02:15] ------------------------------------------
[01:02:15] stderr:
[01:02:15] stderr:
[01:02:15] ------------------------------------------
[01:02:15] error[E0658]: procedural macros cannot expand to modules
[01:02:15] --> /checkout/src/test/run-pass-fulldeps/proc-macro/add-impl.rs:17:10
[01:02:15] |
[01:02:15] 17 | #[derive(AddImpl)]
[01:02:15] |
[01:02:15] = help: add #![feature(proc_macro_mod)] to the crate attributes to enable
[01:02:15] [01:02:15] error: aborting due to previous error
---
[01:02:15] ---- [run-pass] run-pass-fulldeps/proc-macro/crate-var.rs stdout ----
[01:02:15] [01:02:15] error: compilation failed!
[01:02:15] status: exit code: 101
[01:02:15] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/run-pass-fulldeps/proc-macro/crate-var.rs" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps" "--target=x86_64-unknown-linux-gnu" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps/proc-macro/crate-var.stage2-x86_64-unknown-linux-gnu" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps/proc-macro/crate-var.stage2-x86_64-unknown-linux-gnu.aux"
[01:02:15] ------------------------------------------
[01:02:15] [01:02:15] ------------------------------------------
[01:02:15] stderr:
[01:02:15] stderr:
[01:02:15] ------------------------------------------
[01:02:15] error[E0658]: procedural macros cannot expand to modules
[01:02:15] --> /checkout/src/test/run-pass-fulldeps/proc-macro/crate-var.rs:22:14
[01:02:15] |
[01:02:15] 22 | #[derive(Double)]
[01:02:15] ...
[01:02:15] ...
[01:02:15] 25 | m!();
[01:02:15] | ----- in this macro invocation
[01:02:15] = help: add #![feature(proc_macro_mod)] to the crate attributes to enable
[01:02:15] [01:02:15] error: aborting due to previous error
[01:02:15] ---
[01:02:15] [01:02:15] thread 'main' panicked at 'Some tests failed', tools/compiletest/src/main.rs:492:22
[01:02:15] [01:02:15] [01:02:15] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/run-pass-fulldeps" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-pass-fulldeps" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "run-pass" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-3.9/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options " "--target-rustcflags" "-Crpath -O -Zunstable-options -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "3.9.1\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:02:15] [01:02:15] [01:02:15] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:02:15] Build completed unsuccessfully in 0:21:36
[01:02:15] Build completed unsuccessfully in 0:21:36
[01:02:15] Makefile:58: recipe for target 'check' failed
[01:02:15] make: *** [check] Error 1
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:00ac8030
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

bors · 2018-05-10T00:45:20Z

☀️ Test successful - status-travis
State: approved= try=True

aidanhs · 2018-05-12T18:19:56Z

Crater run started.

petrochenkov · 2018-05-16T20:01:39Z

@alexcrichton
We probably should apply the same restriction to macros generating macro_rules! items.

Mark-Simulacrum · 2018-05-17T01:30:02Z

Crater run finished: https://cargobomb-reports.s3.amazonaws.com/pr-50587/index.html.

alexcrichton · 2018-05-17T03:35:29Z

Alrighty-roo, thanks @Mark-Simulacrum! Definitely seems like we can't land this as-is, I'll file a follow-up.

This commit feature gates generating modules and macro definitions in procedural macro expansions. Custom derive is exempt from this check as it would be a large retroactive breaking change (rust-lang#50587). It's hoped that we can hopefully stem the bleeding to figure out a better solution here before opening up the floodgates. The restriction here is specifically targeted at surprising hygiene results [1] that result in non-"copy/paste" behavior. Hygiene and procedural macros is intended to be avoided as much as possible for Macros 1.2 by saying everything is "as if you copy/pasted the code", but modules and macros are sort of weird exceptions to this rule that aren't fully fleshed out. [1]: rust-lang#50504 (comment) cc rust-lang#50504

rustc: Disallow modules and macros in expansions This commit feature gates generating modules and macro definitions in procedural macro expansions. Custom derive is exempt from this check as it would be a large retroactive breaking change (#50587). It's hoped that we can hopefully stem the bleeding to figure out a better solution here before opening up the floodgates. The restriction here is specifically targeted at surprising hygiene results [1] that result in non-"copy/paste" behavior. Hygiene and procedural macros is intended to be avoided as much as possible for Macros 1.2 by saying everything is "as if you copy/pasted the code", but modules and macros are sort of weird exceptions to this rule that aren't fully fleshed out. [1]: #50504 (comment) cc #50504

rust-highfive assigned eddyb May 9, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label May 9, 2018

alexcrichton mentioned this pull request May 9, 2018
proc_macro! expansion can refer to items defined in the root w/o importing them #50504
Closed

wip
37b3c5e

alexcrichton force-pushed the no-modules branch from bf3a1f1 to 37b3c5eCompare May 9, 2018 22:26

kennytm added the S-waiting-on-crater Status: Waiting on a crater run to be completed. label May 9, 2018

alexcrichton closed this May 17, 2018

alexcrichton deleted the no-modules branch May 17, 2018 03:36

alexcrichton mentioned this pull request May 17, 2018
rustc: Disallow modules and macros in expansions #50820
Merged

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WIP: Gate generating `mod` items in procedural macros - #50587

WIP: Gate generating `mod` items in procedural macros#50587
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alexcrichton commented May 9, 2018

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