Improve detection of generics on lang items #87875

asquared31415 · 2021-08-09T03:45:46Z

Adds detection for the required generics for all lang items. Many lang items require an exact or minimum amount of generic arguments and if they don't exist, the compiler will ICE. This does not add any additional validation about bounds on generics or any other lang item restrictions.

Fixes one of the ICEs in #87573

cc @FabianWolff

rust-highfive · 2021-08-09T03:45:49Z

r? @LeSeulArtichaut

(rust-highfive has picked a reviewer for you, use r? to override)

asquared31415 · 2021-08-09T03:49:32Z

Somewhat related to #9307, but not entirely, and does not close it

asquared31415 · 2021-08-09T04:10:35Z

Whelp I "cleaned up" the code and didn't rerun tests by mistake, used a != to compare "less than" by mistake

asquared31415 · 2021-08-09T04:36:50Z

It compiles locally with that feature enabled, weird, guess it's stabilized now though

LeSeulArtichaut

I'm not familiar at all with this code, so I'm going to pass this to someone else.

compiler/rustc_hir/src/lang_items.rs

LeSeulArtichaut · 2021-08-09T14:38:57Z

Per the GitHub suggestions: r? @cjgillot do you want to take this?

cjgillot

Thanks for the PR @asquared31415. I left a few nits.
Could you also squash the commits?

compiler/rustc_passes/src/lang_items.rs

cjgillot · 2021-08-14T13:02:07Z

compiler/rustc_passes/src/lang_items.rs

+        // traits have one for the argument list, generators have one for the
+        // resume argument, and ordering/equality relations have one for the RHS
+        // Some other types like Box and various functions like drop_in_place
+        // have minimum requirements.


IIUC, minimum requirements exist in cases where the other generics can be inferred, either through a function parameter or through defaulted parameters. So, why do some traits (Unsize, CoerceUnsized) have minimum requirements?

cjgillot · 2021-08-14T13:03:51Z

src/test/ui/lang-items/generics/wrong-number-fn.rs

@@ -0,0 +1,14 @@
+#![feature(lang_items,no_core)]


Can all those tests be put in a single file?

I had to make it two, because I have two tests that should compile for a couple different lang items, and one for the ones that error. But they have been merged into two files in the lang-items directory root.

asquared31415 · 2021-08-15T02:27:48Z

Oh no CI failed enough that the bot didn't even post a comment about the failure. How did this break this badly.

compiler/rustc_passes/src/lang_items.rs

asquared31415 · 2021-08-23T14:07:02Z

I'm not sure how to resolve that CI issue. It looks like it's identical to src/test/ui/error-codes/E0152.rs before my changes, but I don't know where that test that is failing CI comes from.

asquared31415 · 2021-08-23T14:14:11Z

Nevermind, I found it, it was in the E0152.md file in rustc_error_codes

cjgillot · 2021-08-23T18:36:11Z

@bors r+

bors · 2021-08-23T18:36:13Z

📌 Commit 385a233 has been approved by cjgillot

rust-log-analyzer · 2021-08-24T11:13:09Z

A job failed! Check out the build log: (web) (plain)

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asquared31415 · 2021-08-25T04:29:44Z

I'm fairly certain that failure was spurious, is there any action I need to take to get it to retry?

BoxyUwU · 2021-08-25T04:37:26Z

@bors retry

bors · 2021-08-25T08:12:19Z

⌛ Testing commit 385a233 with merge 9863bf5...

bors · 2021-08-25T10:58:36Z

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 9863bf5 to master...

Fix ICE when `start` lang item has wrong generics In my previous pr rust-lang#87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type. The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided. Fixes rust-lang#79559, fixes rust-lang#73584, fixes rust-lang#83117 (all duplicates) Relevant to rust-lang#9307 r? ``@cjgillot``

Fix ICE when `start` lang item has wrong generics In my previous pr rust-lang#87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type. The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided. Fixes rust-lang#79559, fixes rust-lang#73584, fixes rust-lang#83117 (all duplicates) Relevant to rust-lang#9307 r? `@cjgillot`

Fix ICE when `start` lang item has wrong generics In my previous pr rust-lang#87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type. The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided. Fixes rust-lang#79559, fixes rust-lang#73584, fixes rust-lang#83117 (all duplicates) Relevant to rust-lang#9307 r? ``@cjgillot``

Fix ICE when `start` lang item has wrong generics In my previous pr rust-lang#87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type. The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided. Fixes rust-lang#79559, fixes rust-lang#73584, fixes rust-lang#83117 (all duplicates) Relevant to rust-lang#9307 r? ```@cjgillot```

Fix ICE when `start` lang item has wrong generics In my previous pr rust-lang#87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type. The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided. Fixes rust-lang#79559, fixes rust-lang#73584, fixes rust-lang#83117 (all duplicates) Relevant to rust-lang#9307 r? ````@cjgillot````

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asquared31415 force-pushed the generic-lang-items branch from 20c30d1 to b5478b7 Compare August 9, 2021 04:36

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asquared31415 force-pushed the generic-lang-items branch from 1f525b3 to 602caed Compare August 15, 2021 01:39

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asquared31415 force-pushed the generic-lang-items branch from c991112 to d7c06cd Compare August 23, 2021 03:59

Detect incorrect number of lang item generics

385a233

asquared31415 force-pushed the generic-lang-items branch from d7c06cd to 385a233 Compare August 23, 2021 14:15

bors removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Aug 23, 2021

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 24, 2021

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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 Aug 25, 2021

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This was referenced Aug 25, 2021

Add str pointer methods #85816

Closed

[Experimental] Split out an UnsafeCoerceUnsized trait from CoerceUnsized #88239

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asquared31415 deleted the generic-lang-items branch August 29, 2021 22:54

asquared31415 mentioned this pull request Sep 9, 2021

Fix ICE when start lang item has wrong generics #88782

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Mark-Simulacrum mentioned this pull request Dec 13, 2021

Add test for issue #83474 #91821

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Improve detection of generics on lang items #87875

Improve detection of generics on lang items #87875

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Improve detection of generics on lang items #87875

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