[RFC-3086] Consider out-of-bound depths of count

[c410-f3r]

Fix #111905

In the matching of macro calls and their respective declarations (transcribe), a warning is issued if count has a depth greater than the number of nested NamedMatchs through be verification of MatchedSeq with empty elements.

Doesn't affect ( $( { $( [ $( ( $( $t:ident )* ) )* ] )* } )* ) => { ${count(t, 1)} } called with bar!( { [] [] } ) which will still continue to output 2.

[rustbot]

r? @davidtwco

(rustbot has picked a reviewer for you, use r? to override)

[c410-f3r]

r? compiler

[oli-obk]

I'm on vacation and won't get to this before the 19th

Also cc @petrochenkov for macro stuff

[oli-obk]

@bors try

[bors]

⌛ Trying commit c218557ac737a43e768bd2736ead296b3fb6a7b5 with merge 5723d0448b9ce6bed8424358575f87427ecc6050...

[c410-f3r]

@oli-obk count is part of the nightly macro_metavar_expr feature and this PR is fixing a logical error that should be rare to appear in practice.

needs-fcp: This change is insta-stable, so needs a completed FCP to proceed.

That said, I think a FCP isn't necessary.

[oli-obk]

Oh I didn't realize that. I just saw the behaviour change...

@craterbot cancel

[oli-obk]

@craterbot abort

[bors]

⌛ Testing commit 0366888 with merge ce62cbcd4aba08c32632d7805d200eaf53a96a98...

[bors]

💔 Test failed - checks-actions

[c410-f3r]

Well, the matter needs more investigation on my side

[oli-obk]

@rustbot author

[ehuss]

@bors r-

bors synchronize queue fix

[Dylan-DPC]

@c410-f3r any updates on this?

[c410-f3r]

CI failure still can't be reproduced locally.

@oli-obk Can you r? again so I can see the logs? All previous runs are now 404.

[rustbot]

Failed to set assignee to again: cannot assign: response: {"message":"Not Found","documentation_url":"https://docs.github.com/rest/issues/assignees#add-assignees-to-an-issue"}

Note: Only org members with at least the repository "read" role, users with write permissions, or people who have commented on the PR may be assigned.

[oli-obk]

@bors r+

[bors]

📌 Commit 82ba5fb has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 82ba5fb with merge 33e81da...

[rust-log-analyzer]

The job i686-gnu failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

-   --> $DIR/issue-111905.rs:4:26
+ error: only unsuffixes integer literals are supported in meta-variable expressions
+   --> $DIR/issue-111905.rs:4:27
3    |
4 LL |     ($($t:ident)*) => { ${count(t, 4294967296)} };
+    |                           ^^^^^
6 
- error: related fragment that refers the `count` meta-variable expression was not found
-   --> $DIR/issue-111905.rs:9:60
-   --> $DIR/issue-111905.rs:9:60
+ error: only unsuffixes integer literals are supported in meta-variable expressions
+   --> $DIR/issue-111905.rs:9:61
9    |
10 LL |     ( $( { $( [ $( ( $( $t:ident )* ) )* ] )* } )* ) => { ${count(t, 4294967296)} }
+    |                                                             ^^^^^
12 
- error: aborting due to 2 previous errors
+ error: expected expression, found `$`
+ error: expected expression, found `$`
+   --> $DIR/issue-111905.rs:4:25
+    |
+ LL |     ($($t:ident)*) => { ${count(t, 4294967296)} };
+ ...
+ LL |     foo!();
+    |     ------ in this macro invocation
+    |
+    |
+    = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
+ 
+ error: expected expression, found `$`
+   --> $DIR/issue-111905.rs:9:59
+    |
+ LL |     ( $( { $( [ $( ( $( $t:ident )* ) )* ] )* } )* ) => { ${count(t, 4294967296)} }
+ ...
+ ...
+ LL |     bar!( { [] [] } );
+    |
+    = note: this error originates in the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)
+ 
+ error: aborting due to 4 previous errors
---
To only update this specific test, also pass `--test-args macros/rfc-3086-metavar-expr/issue-111905.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: RUSTC_ICE="0" "/checkout/obj/build/i686-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/macros/rfc-3086-metavar-expr/issue-111905.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "--sysroot" "/checkout/obj/build/i686-unknown-linux-gnu/stage2" "--target=i686-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/i686-unknown-linux-gnu/test/ui/macros/rfc-3086-metavar-expr/issue-111905" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/i686-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/i686-unknown-linux-gnu/test/ui/macros/rfc-3086-metavar-expr/issue-111905/auxiliary"
--- stderr -------------------------------
error: only unsuffixes integer literals are supported in meta-variable expressions
##[error]  --> /checkout/tests/ui/macros/rfc-3086-metavar-expr/issue-111905.rs:4:27
   |
   |
LL |     ($($t:ident)*) => { ${count(t, 4294967296)} };

error: only unsuffixes integer literals are supported in meta-variable expressions
##[error]  --> /checkout/tests/ui/macros/rfc-3086-metavar-expr/issue-111905.rs:9:61
   |
   |
LL |     ( $( { $( [ $( ( $( $t:ident )* ) )* ] )* } )* ) => { ${count(t, 4294967296)} }

error: expected expression, found `$`
##[error]  --> /checkout/tests/ui/macros/rfc-3086-metavar-expr/issue-111905.rs:4:25
   |
   |
LL |     ($($t:ident)*) => { ${count(t, 4294967296)} };
...
LL |     foo!();
   |     ------ in this macro invocation
   |
   |
   = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)

error: expected expression, found `$`
##[error]  --> /checkout/tests/ui/macros/rfc-3086-metavar-expr/issue-111905.rs:9:59
   |
LL |     ( $( { $( [ $( ( $( $t:ident )* ) )* ] )* } )* ) => { ${count(t, 4294967296)} }
...
...
LL |     bar!( { [] [] } );
   |
   = note: this error originates in the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 4 previous errors

[bors]

💔 Test failed - checks-actions

[c410-f3r]

Thank you @oli-obk

I spent several hours trying to find a solution and nothing worked. Now I don't have the time or motivation to continue pursuing this PR.