Add lint for unused macros #41907

est31 · May 11, 2017

Addresses parts of #34938, to add a lint for unused macros.

We now output warnings by default when we encounter a macro that we didn't use for expansion.

Issues to be resolved before this PR is ready for merge:

fix the NodeId issue described above
remove all unused macros from rustc and the libraries or set #[allow(unused_macros)] next to them if they should be kept for some reason. This is needed for successful boostrap and bors to accept the PR. -> #41934
~~implement the full extent of #34938, that means the macro match arm checking as well.~~ let's not do this for now

rust-highfive · May 11, 2017

r? @pnkfelix

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

est31 · May 11, 2017

r? @jseyfried because you seem to have done many things with macros in the past, so might know the code best.

est31 · May 11, 2017

Hmmm, I suspect that the lint checker requires something to be present under the NodeId we give it, so we can't just bail out by creating some random one, but I guess we'll need to create our own special ExprKind like UnusedMac or something that then lives on until the linter runs.

est31 · May 12, 2017

Okay, apparently macro definitions do survive inside the AST (but not in the hir), only have to add handling for them in the lint code. Update incoming. I've also found some occurences of unused macros inside the codebase,

petrochenkov · May 13, 2017

If @jseyfried doesn't appear, then r=me after #41934 is merged.

est31 · May 13, 2017

okay, ready for review. r? @jseyfried

jseyfried · May 15, 2017

jseyfried reviewed May 15, 2017

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Looks good! r=me modulo comments

jseyfried · May 15, 2017

src/librustc_resolve/macros.rs

+            let id_span = match *self.macro_map[did] {
+                           SyntaxExtension::NormalTT(_, isp, _) => isp,
+                           _ => None
+                       };


nit: this is usually formatted

let id_span = match *self.macro_map[did] { SyntaxExtension::NormalTT(_, isp, _) => isp, _ => None };

jseyfried · May 15, 2017

src/libcore/num/wrapping.rs

@@ -12,6 +12,7 @@ use super::Wrapping;

 use ops::*;

+#[allow(unused_macros)]


Is there a reason we can't just remove the unused macro here?

There is a FIXME below to get the remaining impls uncommented, including invocations of the macro.

Makes sense.

jseyfried · May 15, 2017

src/libsyntax/ext/tt/macro_rules.rs

+             exp,
+             Some((def.id, def.span)),
+             attr::contains_name(&def.attrs, "allow_internal_unstable")
+    )


nit: nonstandard formatting -- should be three lines with "visual indenting" or indented one block with four/five lines.

jseyfried · May 15, 2017

src/librustc_resolve/lib.rs

+    // List of macros that we need to warn about as being unused.
+    // The bool is true if the macro is unused, and false if its used.
+    // Setting a bool to false should be much faster than removing a single
+    // element from a FxHashSet.


Could you clarify that this is only for crate-local macro_rules!?

Okay, but hopefully the upcoming macros 2.0 macros could be included as well.

jseyfried · May 15, 2017

src/librustc_resolve/lib.rs

+    // The bool is true if the macro is unused, and false if its used.
+    // Setting a bool to false should be much faster than removing a single
+    // element from a FxHashSet.
+    unused_macros: FxHashMap<DefId, bool>,


I still think this should be an FxHashSet<DefId> -- I believe the perf difference is negligible here (removing a value from a hash set is already many orders of magnitude faster than the rest the processing we do per used crate-local macro_rules!).

est31 · May 15, 2017

updated. re-r? @jseyfried

bors · May 15, 2017

📌 Commit 25b7f10 has been approved by jseyfried

est31 · May 16, 2017

Had to update due to this failure. re-r? @jseyfried

jseyfried · May 16, 2017

@bors r+

bors · May 16, 2017

📌 Commit 6dbd706 has been approved by jseyfried

bors · May 16, 2017

⌛️ Testing commit 6dbd706 with merge 9ccc84d...

bors · May 16, 2017

💔 Test failed - status-travis

Mark-Simulacrum · May 16, 2017


[01:15:04] ---- concurrent_installs stdout ----

[01:15:04] 	thread 'concurrent_installs' panicked at '

[01:15:04] Expected: execs

[01:15:04]     but: exited with exit code: 101

[01:15:04] --- stdout

[01:15:04] 

[01:15:04] --- stderr

[01:15:04]     Updating registry `file:///checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/cit/t0/registry`

[01:15:04]     Blocking waiting for file lock on the registry index

[01:15:04] error: could not find `foo` in `registry https://github.com/rust-lang/crates.io-index`

[01:15:04] ', /cargo/registry/src/github.com-1ecc6299db9ec823/hamcrest-0.1.1/src/core.rs:31

[01:15:04] note: Run with `RUST_BACKTRACE=1` for a backtrace.

[01:15:04] 

[01:15:04] 

[01:15:04] failures:

[01:15:04]     concurrent_installs

I think this was recently fixed, but the update to the cargo submodule hasn't been pulled in yet (if the PR was even merged)

@bors retry

alexcrichton · May 16, 2017

FWIW that was fixed by rust-lang/cargo#4051 and we'll get the update in #42039

bors · May 16, 2017

⌛️ Testing commit 6dbd706 with merge 86319e4...

bors · May 17, 2017

☀️ Test successful - status-appveyor, status-travis
Approved by: jseyfried
Pushing 86319e4 to master...

rust-highfive assigned pnkfelix May 11, 2017

rust-highfive assigned jseyfried and unassigned pnkfelix May 11, 2017

alexcrichton added the S-waiting-on-review label May 11, 2017

est31 force-pushed the est31:macro_unused branch 5 times, most recently from 0c72cd2 to a97a1c5 May 12, 2017

est31 force-pushed the est31:macro_unused branch from a97a1c5 to b36d23c May 13, 2017

est31 changed the title ~~Add lint for unused macros [WIP]~~ Add lint for unused macros May 13, 2017

librustc_incremental: remove unused macro in test case

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0d0cb27

Address review comments

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25b7f10

frewsxcv referenced this pull request May 16, 2017
Closed
Rollup of 6 pull requests #42022

bors added a commit that referenced this pull request May 16, 2017

Auto merge of #42022 - frewsxcv:rollup, r=frewsxcv
Rollup of 6 pull requests - Successful merges: #41489, #41771, #41907, #41982, #41994, #41995 - Failed merges:

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c0f8f4e

bors added a commit that referenced this pull request May 16, 2017

Auto merge of #42022 - frewsxcv:rollup, r=frewsxcv
Rollup of 6 pull requests - Successful merges: #41489, #41771, #41907, #41982, #41994, #41995 - Failed merges:

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9581366

put option_try macro def under #[cfg(unix)]

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6dbd706

Mark-Simulacrum referenced this pull request May 16, 2017
Closed
Rollup of 8 pull requests #42032

bors added a commit that referenced this pull request May 16, 2017

Auto merge of #42032 - Mark-Simulacrum:rollup, r=Mark-Simulacrum
Rollup of 8 pull requests - Successful merges: #41489, #41907, #41932, #41982, #41994, #41995, #42001, #42005 - Failed merges:

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be3a003

arielb1 added S-waiting-on-bors and removed S-waiting-on-review labels May 16, 2017

bors merged commit 6dbd706 into rust-lang:master May 17, 2017
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Merged

Change some notes into suggestions #42033

Merged

Initial implementation of declarative macros 2.0 #40847

malbarbo referenced this pull request May 24, 2017
Merged
Add x86_64-linux-android build support #98

bors added a commit that referenced this pull request Jun 3, 2017

Auto merge of #42334 - est31:master, r=jseyfried
Extend the unused macro lint to macros 2.0 Extends the unused macro lint (added in PR #41907) to macros 2.0 (added in PR #40847). r? @jseyfried

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a8dc246

brson added the relnotes label Jun 6, 2017

hcpl referenced this pull request Sep 6, 2017
Closed
"unused `#[macro_use]` import" false positive in libs and unit-tests #44342

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est31 commented May 11, 2017 • edited

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est31 added some commits May 11, 2017

est31 force-pushed the est31:macro_unused branch from a97a1c5 to b36d23c May 13, 2017

est31 changed the title Add lint for unused macros [WIP] Add lint for unused macros May 13, 2017

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Hide details View details bors merged commit 6dbd706 into rust-lang:master May 17, 2017 2 checks passed

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est31 commented May 11, 2017 •

edited

est31 force-pushed the est31:macro_unused branch 5 times, most recently from `0c72cd2` to `a97a1c5` May 12, 2017

est31 force-pushed the est31:macro_unused branch from `a97a1c5` to `b36d23c` May 13, 2017

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bors merged commit `6dbd706` into rust-lang:master May 17, 2017
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