rust: handle modules with same crate_name

crate_name do not need to be unique. A library may depend on two
different versions of the same crate. Use the module name instead of the
crate name when indexing the modules for rust-project.json.

Test: SOONG_GEN_RUST_PROJECT=1 m nothing
Bug: 162896400
Change-Id: I275f04639ef05f2b649c30168046e13b2efcacb9

rust/project_json_test.go

@@ -117,3 +117,55 @@ func TestProjectJsonBindGen(t *testing.T) {
 	jsonContent := testProjectJson(t, bp, fs)
 	validateJsonCrates(t, jsonContent)
 }
+
+func TestProjectJsonMultiVersion(t *testing.T) {
+	bp := `
+	rust_library {
+		name: "liba1",
+		srcs: ["a1/src/lib.rs"],
+		crate_name: "a"
+	}
+	rust_library {
+		name: "liba2",
+		srcs: ["a2/src/lib.rs"],
+		crate_name: "a",
+	}
+	rust_library {
+		name: "libb",
+		srcs: ["b/src/lib.rs"],
+		crate_name: "b",
+		rustlibs: ["liba1", "liba2"],
+	}
+	` + GatherRequiredDepsForTest()
+	fs := map[string][]byte{
+		"a1/src/lib.rs": nil,
+		"a2/src/lib.rs": nil,
+		"b/src/lib.rs":  nil,
+	}
+	jsonContent := testProjectJson(t, bp, fs)
+	crates := validateJsonCrates(t, jsonContent)
+	for _, crate := range crates {
+		c := crate.(map[string]interface{})
+		if c["root_module"] == "b/src/lib.rs" {
+			deps, ok := c["deps"].([]interface{})
+			if !ok {
+				t.Errorf("Unexpected format for deps: %v", c["deps"])
+			}
+			aCount := 0
+			for _, dep := range deps {
+				d, ok := dep.(map[string]interface{})
+				if !ok {
+					t.Errorf("Unexpected format for dep: %v", dep)
+				}
+				if d["name"] == "a" {
+					aCount++
+				}
+			}
+			if aCount != 2 {
+				t.Errorf("Unexpected number of liba dependencies want %v, got %v: %v", 2, aCount, deps)
+			}
+			return
+		}
+	}
+	t.Errorf("libb crate has not been found: %v", crates)
+}