rustc: Filter out bogus extern crate warnings #46405
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Rustdoc has for some time now used the "everybody loops" pass in the compiler to avoid typechecking and otherwise avoid looking at implementation details. In rust-lang#46115 the placement of this pass was pushed back in the compiler to after macro expansion to ensure that it works with macro-expanded code as well. This in turn caused the regression in rust-lang#46271. The bug here was that the resolver was producing `def_id` instances for "possibly unused extern crates" which would then later get processed during typeck to actually issue lint warnings. The problem was that *after* resolution these `def_id` nodes were actually removed from the AST by the "everybody loops" pass. This later, when we tried to take a look at `def_id`, caused the compiler to panic. The fix applied here is a bit of a heavy hammer which is to just, in this one case, ignore the `extern crate` lints if the `def_id` looks "bogus" in any way (basically if it looks like the node was removed after resolution). The real underlying bug here is probably that the "everybody loops" AST pass is being stressed to much beyond what it was originally intended to do, but this should at least fix the ICE for now... Closes rust-lang#46271
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r? @estebank (rust_highfive has picked a reviewer for you, use r? to override) |
kennytm
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@bors r+ rollup |
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📌 Commit 4e74eb5 has been approved by |
estebank
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Since it's a critical bug, I give it a high priority. @bors: p=10 |
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Dec 1, 2017
rustc: Filter out bogus extern crate warnings Rustdoc has for some time now used the "everybody loops" pass in the compiler to avoid typechecking and otherwise avoid looking at implementation details. In rust-lang#46115 the placement of this pass was pushed back in the compiler to after macro expansion to ensure that it works with macro-expanded code as well. This in turn caused the regression in rust-lang#46271. The bug here was that the resolver was producing `def_id` instances for "possibly unused extern crates" which would then later get processed during typeck to actually issue lint warnings. The problem was that *after* resolution these `def_id` nodes were actually removed from the AST by the "everybody loops" pass. This later, when we tried to take a look at `def_id`, caused the compiler to panic. The fix applied here is a bit of a heavy hammer which is to just, in this one case, ignore the `extern crate` lints if the `def_id` looks "bogus" in any way (basically if it looks like the node was removed after resolution). The real underlying bug here is probably that the "everybody loops" AST pass is being stressed to much beyond what it was originally intended to do, but this should at least fix the ICE for now... Closes rust-lang#46271
This was referenced Dec 1, 2017
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@GuillaumeGomez The p=10 has no effect when rollup is still active 😕. |
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@kennytm sorry about that, didn't realize that was a side effect :-/ |
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Rustdoc has for some time now used the "everybody loops" pass in the compiler to
avoid typechecking and otherwise avoid looking at implementation details.
In #46115 the placement of this pass was pushed back in the compiler to after
macro expansion to ensure that it works with macro-expanded code as well. This
in turn caused the regression in #46271.
The bug here was that the resolver was producing
def_idinstances for"possibly unused extern crates" which would then later get processed during
typeck to actually issue lint warnings. The problem was that after resolution
these
def_idnodes were actually removed from the AST by the "everybody loops"pass. This later, when we tried to take a look at
def_id, caused the compilerto panic.
The fix applied here is a bit of a heavy hammer which is to just, in this one
case, ignore the
extern cratelints if thedef_idlooks "bogus" in any way(basically if it looks like the node was removed after resolution). The real
underlying bug here is probably that the "everybody loops" AST pass is being
stressed to much beyond what it was originally intended to do, but this should
at least fix the ICE for now...
Closes #46271