rename our proc-macro test crate to a more clear name

and remove serde_derive, since the --extern .so file was really just a consequence of building a proc macro

Author: RalfJung

test-cargo-miri/Cargo.lock

@@ -12,20 +12,19 @@ edition = "2018"
 byteorder = "1.0"
 cdylib = { path = "cdylib" }
 exported_symbol = { path = "exported-symbol" }
+proc_macro_crate = { path = "proc-macro-crate" }
 issue_1567 = { path = "issue-1567" }
 issue_1691 = { path = "issue-1691" }
 issue_1705 = { path = "issue-1705" }
-issue_1760 = { path = "issue-1760" }
 issue_rust_86261 = { path = "issue-rust-86261" }
 
 [dev-dependencies]
 byteorder_2 = { package = "byteorder", version = "0.5" } # to test dev-dependencies behave as expected, with renaming
 ## More dependencies that we don't actually use, but add just for extra test coverage.
-# Exercises some unique code path (`--extern` .so file).
-serde_derive = "1.0.185"
 # These use custom build probes, let's make sure they don't explode.
 # (Ideally we'd check if the probe was successful, but that's not easily possible.)
-# proc-macro2 is extra exciting because it is both a host-dependency and a target-dependency.
+# proc-macro2 is extra exciting because it is both a host-dependency (of proc_macro_crate above)
+# and a target-dependency.
 proc-macro2 = "1.0"
 eyre = "0.6"
 

test-cargo-miri/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+# regression test for issue 1760
+name = "proc_macro_crate"
+version = "0.1.0"
+authors = ["Miri Team"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+# A common dependency of proc macros, let's make sure that works.
+proc-macro2 = "1.0"

test-cargo-miri/issue-1760/Cargo.toml

@@ -28,9 +28,9 @@
 /// ```
 #[no_mangle]
 pub fn make_true() -> bool {
+    proc_macro_crate::use_the_dependency!();
     issue_1567::use_the_dependency();
     issue_1705::use_the_dependency();
-    issue_1760::use_the_dependency!();
     issue_1691::use_me()
 }