Rollup merge of #39619 - michaelwoerister:rename-crate-metadata, r=alexcrichton

Choose different name for metadata obj-file to avoid clashes with user-chosen names.

Fixes #39585 and probably https://github.com/rust-lang/rust/issues/39508.
Incremental compilation assigns different names to obj-files than regular compilation. If a crate is called "metadata" this can lead to a clash between the root module's obj-file and the obj-file containing crate-metadata. This PR assigns a name to the metadata obj-file that cannot clash with other obj-file because it contains a `.` which is not allowed in a Rust module identifier.

r? @alexcrichton

cc @nikomatsakis

src/librustc_trans/back/link.rs

@@ -48,6 +48,13 @@ use syntax::attr;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
 
+/// The LLVM module name containing crate-metadata. This includes a `.` on
+/// purpose, so it cannot clash with the name of a user-defined module.
+pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
+/// The name of the crate-metadata object file the compiler generates. Must
+/// match up with `METADATA_MODULE_NAME`.
+pub const METADATA_OBJ_NAME: &'static str = "crate.metadata.o";
+
 // RLIB LLVM-BYTECODE OBJECT LAYOUT
 // Version 1
 // Bytes    Data
@@ -213,7 +220,7 @@ pub fn link_binary(sess: &Session,
                 remove(sess, &obj);
             }
         }
-        remove(sess, &outputs.with_extension("metadata.o"));
+        remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
     }
 
     out_filenames
@@ -832,7 +839,7 @@ fn link_args(cmd: &mut Linker,
     // object file, so we link that in here.
     if crate_type == config::CrateTypeDylib ||
        crate_type == config::CrateTypeProcMacro {
-        cmd.add_object(&outputs.with_extension("metadata.o"));
+        cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
     }
 
     // Try to strip as much out of the generated object by removing unused

src/librustc_trans/back/write.rs

@@ -886,12 +886,12 @@ pub fn run_passes(sess: &Session,
     // Clean up unwanted temporary files.
 
     // We create the following files by default:
-    //  - crate.#module-name#.bc
-    //  - crate.#module-name#.o
-    //  - crate.metadata.bc
-    //  - crate.metadata.o
-    //  - crate.o (linked from crate.##.o)
-    //  - crate.bc (copied from crate.##.bc)
+    //  - #crate#.#module-name#.bc
+    //  - #crate#.#module-name#.o
+    //  - #crate#.crate.metadata.bc
+    //  - #crate#.crate.metadata.o
+    //  - #crate#.o (linked from crate.##.o)
+    //  - #crate#.bc (copied from crate.##.bc)
     // We may create additional files if requested by the user (through
     // `-C save-temps` or `--emit=` flags).
 
@@ -939,9 +939,9 @@ pub fn run_passes(sess: &Session,
     }
 
     // We leave the following files around by default:
-    //  - crate.o
-    //  - crate.metadata.o
-    //  - crate.bc
+    //  - #crate#.o
+    //  - #crate#.crate.metadata.o
+    //  - #crate#.bc
     // These are used in linking steps and will be cleaned up afterward.
 
     // FIXME: time_llvm_passes support - does this use a global context or

src/librustc_trans/base.rs

@@ -1151,7 +1151,7 @@ pub fn trans_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     });
 
     let metadata_module = ModuleTranslation {
-        name: "metadata".to_string(),
+        name: link::METADATA_MODULE_NAME.to_string(),
         symbol_name_hash: 0, // we always rebuild metadata, at least for now
         source: ModuleSource::Translated(ModuleLlvm {
             llcx: shared_ccx.metadata_llcx(),