found two different crates with name rustc_demangle that are not distinguished by differing -C metadata

[udoprog]

When building latest master with ./x.py build -i, I get the following error:

(Sorry about the image, but multiline copy+paste is currently broken in my dev build of windows terminal.)

Error pasted for search:

found two different crates with name `rustc_demangle` that are not distinguished by differing `-C metadata`. This will result in symbol conflicts between the two.

Note that I've also applied this patch to solve the build breakage on msvc 2019.

Forcibly downgrading or specifying the version to to =0.1.14 like this solves the issue, but I have no idea why it happens in the first place:

diff --git a/src/librustc_codegen_llvm/Cargo.toml b/src/librustc_codegen_llvm/Cargo.toml
index 4ae8303c76..134ac8625f 100644
--- a/src/librustc_codegen_llvm/Cargo.toml
+++ b/src/librustc_codegen_llvm/Cargo.toml
@@ -13,7 +13,7 @@ test = false
 [dependencies]
 cc = "1.0.1" # Used to locate MSVC
 num_cpus = "1.0"
-rustc-demangle = "0.1.15"
+rustc-demangle = "=0.1.14"
 rustc_llvm = { path = "../librustc_llvm" }
 memmap = "0.6"
 
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index a4cb517faf..66bdde6723 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -14,7 +14,7 @@ test = false
 bitflags = "1.0.4"
 cc = "1.0.1"
 num_cpus = "1.0"
-rustc-demangle = "0.1.15"
+rustc-demangle = "=0.1.14"
 memmap = "0.6"
 log = "0.4.5"
 libc = "0.2.44"
diff --git a/src/librustc_codegen_utils/Cargo.toml b/src/librustc_codegen_utils/Cargo.toml
index b218d18a06..4e32caf134 100644
--- a/src/librustc_codegen_utils/Cargo.toml
+++ b/src/librustc_codegen_utils/Cargo.toml
@@ -14,7 +14,7 @@ test = false
 flate2 = "1.0"
 log = "0.4"
 punycode = "0.4.0"
-rustc-demangle = "0.1.15"
+rustc-demangle = "=0.1.14"
 
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }

[jonas-schievink]

Does it happen after ./x.py clean as well?

[udoprog]

This was a clean checkout, but I'll give it a try ASAP.

[udoprog]

Also, I forgot to mention that I'm building with -i (--incremental). Edited the original post.

[jonas-schievink]

Ah okay, I've sometimes seen something like this happen after git pulling when there's already stuff built, but if it's a clean checkout that's not the same problem.

[udoprog]

Cleaning fixed it. Must've been something that happened during the initial build failure when I applied the patch to fix the MSVC 2019 build failure.

Thanks!