Store a valid name for the root module in metadata

[mitaa]

f357d55 caused a regression by retrieving item names from metadata, while previously using the last element of its absolute path (which in the case of a root module is the prefixed crate name since the stored path in metadata is empty)

fixes #28927

[rust-highfive]

r? @arielb1

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[alexcrichton]

Thanks! Could you also add a test for this?

[mitaa]

I added a test, though I didn't yet have time to actually run it through make check...

[mitaa]

(test fixed)

[arielb1]

@bors r+ rollup 528d086

[bors]

📌 Commit 528d086 has been approved by arielb1

[bors]

⌛ Testing commit 528d086 with merge 04942ca...

[bors]

💔 Test failed - auto-linux-musl-64-opt

[mitaa]

89b6f39

 // aux-build:issue-28927-2.rs
 // aux-build:issue-28927-1.rs
+// ignore-cross-compile

 extern crate issue_28927_1 as inner1;
 pub use inner1 as foo;

[mitaa]

(fixed test and squashed)

[alexcrichton]

@bors: r=arielb1 02f9a49

[bors]

⌛ Testing commit 02f9a49 with merge 531b053...

[alexcrichton]

@bors: retry force

[bors]

⚡ Previous build results for auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-64-opt, auto-win-msvc-32-opt are reusable. Rebuilding only auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-64-opt...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt

[IvanUkhov]

@mitaa, thanks!