Rollup merge of #64324 - alexcrichton:share-generics-again, r=michaelwoerister

rustc: Fix mixing crates with different `share_generics`

This commit addresses #64319 by removing the `dylib` crate type from the
list of crate type that exports generic symbols. The bug in #64319
arises because a `dylib` crate type was trying to export a symbol in an
uptream crate but it miscalculated the symbol name of the uptream
symbol. This isn't really necessary, though, since `dylib` crates aren't
that heavily used, so we can just conservatively say that the `dylib`
crate type never exports generic symbols, forcibly removing them from
the exported symbol lists if were to otherwise find them.

The fix here happens in two places:

* First is in the `local_crate_exports_generics` method, indicating that
  it's now `false` for the `Dylib` crate type. Only rlibs actually
  export generics at this point.

* Next is when we load exported symbols from upstream crate. If, for our
  compilation session, the crate may be included from a dynamic library,
  then its generic symbols are removed. When the crate was linked into a
  dynamic library its symbols weren't exported, so we can't consider
  them a candidate to link against.

Overally this should avoid situations where we incorrectly calculate the
upstream symbol names in the face of differnet `share_generics` options,
ultimately...

Closes #64319

src/test/codegen-units/partitioning/auxiliary/shared_generics_aux.rs

@@ -1,4 +1,5 @@
 // compile-flags:-Zshare-generics=yes
+// no-prefer-dynamic
 
 #![crate_type="rlib"]
 

src/test/codegen-units/partitioning/shared-generics.rs

@@ -1,4 +1,5 @@
 // ignore-tidy-linelength
+// no-prefer-dynamic
 // compile-flags:-Zprint-mono-items=eager -Zshare-generics=yes -Zincremental=tmp/partitioning-tests/shared-generics-exe
 
 #![crate_type="rlib"]

src/test/compile-fail/two-panic-runtimes.rs

@@ -5,6 +5,7 @@
 // aux-build:panic-runtime-lang-items.rs
 
 #![no_std]
+#![no_main]
 
 extern crate panic_runtime_unwind;
 extern crate panic_runtime_unwind2;

src/test/run-make-fulldeps/issue-64319/Makefile

@@ -0,0 +1,39 @@
+-include ../tools.mk
+
+# Different optimization levels imply different values for `-Zshare-generics`,
+# so try out a whole bunch of combinations to make sure everything is compatible
+all:
+	# First up, try some defaults
+	$(RUSTC) --crate-type rlib foo.rs
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=3
+
+	# Next try mixing up some things explicitly
+	$(RUSTC) --crate-type rlib foo.rs -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=no
+	$(RUSTC) --crate-type rlib foo.rs -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=yes
+	$(RUSTC) --crate-type rlib foo.rs -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=no
+	$(RUSTC) --crate-type rlib foo.rs -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=yes
+
+	# Now combine a whole bunch of options together
+	$(RUSTC) --crate-type rlib foo.rs
+	$(RUSTC) --crate-type dylib bar.rs
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=1
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=1 -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=1 -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=2
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=2 -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=2 -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=3
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=3 -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=3 -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=s
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=s -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=s -Z share-generics=yes
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=z
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=z -Z share-generics=no
+	$(RUSTC) --crate-type dylib bar.rs -C opt-level=z -Z share-generics=yes

src/test/run-make-fulldeps/issue-64319/bar.rs

@@ -0,0 +1,5 @@
+extern crate foo;
+
+pub fn bar() {
+    foo::foo();
+}

src/test/run-make-fulldeps/issue-64319/foo.rs

@@ -0,0 +1,9 @@
+pub fn foo() {
+    bar::<usize>();
+}
+
+pub fn bar<T>() {
+    baz();
+}
+
+fn baz() {}

src/test/run-make-fulldeps/symbol-visibility/Makefile

@@ -79,12 +79,12 @@ all:
 	# Check that a Rust dylib exports its monomorphic functions, including generics this time
 	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_c_function_from_rust_dylib)" -eq "1" ]
 	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_rust_function_from_rust_dylib)" -eq "1" ]
-	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_generic_function_from_rust_dylib)" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_generic_function_from_rust_dylib)" -eq "0" ]
 
 	# Check that a Rust dylib exports the monomorphic functions from its dependencies
 	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_c_function_from_rlib)" -eq "1" ]
 	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_rust_function_from_rlib)" -eq "1" ]
-	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_generic_function_from_rlib)" -eq "1" ]
+	[ "$$($(NM) $(TMPDIR)/$(RDYLIB_NAME) | grep -c public_generic_function_from_rlib)" -eq "0" ]
 
 	# Check that an executable does not export any dynamic symbols
 	[ "$$($(NM) $(TMPDIR)/$(EXE_NAME) | grep -c public_c_function_from_rlib)" -eq "0" ]

src/test/ui/panic-runtime/transitive-link-a-bunch.rs

@@ -7,9 +7,8 @@
 // ignore-wasm32-bare compiled with panic=abort by default
 
 #![no_std]
+#![no_main]
 
 extern crate wants_panic_runtime_unwind;
 extern crate wants_panic_runtime_abort;
 extern crate panic_runtime_lang_items;
-
-fn main() {}

src/test/ui/panic-runtime/want-unwind-got-abort.rs

@@ -4,8 +4,7 @@
 // ignore-wasm32-bare compiled with panic=abort by default
 
 #![no_std]
+#![no_main]
 
 extern crate panic_runtime_abort;
 extern crate panic_runtime_lang_items;
-
-fn main() {}

src/test/ui/panic-runtime/want-unwind-got-abort2.rs

@@ -5,8 +5,7 @@
 // ignore-wasm32-bare compiled with panic=abort by default
 
 #![no_std]
+#![no_main]
 
 extern crate wants_panic_runtime_abort;
 extern crate panic_runtime_lang_items;
-
-fn main() {}