Note different versions of same crate when absolute paths of different types match.

src/test/run-make/type-mismatch-same-crate-name/Makefile

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+-include ../tools.mk
+
+all:
+	# compile two different versions of crateA
+	$(RUSTC) --crate-type=rlib crateA.rs -C metadata=-1 -C extra-filename=-1
+	$(RUSTC) --crate-type=rlib crateA.rs -C metadata=-2 -C extra-filename=-2
+	# make crateB depend on version 1 of crateA
+	$(RUSTC) --crate-type=rlib crateB.rs --extern crateA=$(TMPDIR)/libcrateA-1.rlib
+	# make crateC depend on version 2 of crateA
+	$(RUSTC) crateC.rs --extern crateA=$(TMPDIR)/libcrateA-2.rlib 2>&1 | \
+		grep -z \
+	"mismatched types.*\
+	crateB::try_foo(foo2);.*\
+	expected struct \`crateA::foo::Foo\`, found struct \`crateA::Foo\`.*\
+	different versions of crate \`crateA\`.*\
+	mismatched types.*\
+	crateB::try_bar(bar2);.*\
+	expected trait \`crateA::bar::Bar\`, found trait \`crateA::Bar\`.*\
+	different versions of crate \`crateA\`"

src/test/run-make/type-mismatch-same-crate-name/crateA.rs

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+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+mod foo {
+    pub struct Foo;
+}
+
+mod bar {
+    pub trait Bar{}
+
+    pub fn bar() -> Box<Bar> {
+        unimplemented!()
+    }
+}
+
+// This makes the publicly accessible path
+// differ from the internal one.
+pub use foo::Foo;
+pub use bar::{Bar, bar};

src/test/run-make/type-mismatch-same-crate-name/crateB.rs

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+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+extern crate crateA;
+
+pub fn try_foo(x: crateA::Foo){}
+pub fn try_bar(x: Box<crateA::Bar>){}

src/test/run-make/type-mismatch-same-crate-name/crateC.rs

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+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// This tests the extra note reported when a type error deals with
+// seemingly identical types.
+// The main use case of this error is when there are two crates
+// (generally different versions of the same crate) with the same name
+// causing a type mismatch.
+
+// The test is nearly the same as the one in
+// compile-fail/type-mismatch-same-crate-name.rs
+// but deals with the case where one of the crates
+// is only introduced as an indirect dependency.
+// and the type is accessed via a reexport.
+// This is similar to how the error can be introduced
+// when using cargo's automatic dependency resolution.
+
+extern crate crateA;
+
+fn main() {
+    let foo2 = crateA::Foo;
+    let bar2 = crateA::bar();
+    {
+        extern crate crateB;
+        crateB::try_foo(foo2);
+        crateB::try_bar(bar2);
+    }
+}