Add a test that covers the error

Signed-off-by: Lucas Pluvinage <lucas.pluvinage@gmail.com>

test/blackbox-tests/test-cases/variants/run.t

@@ -17,8 +17,8 @@ variants results in an appropriate error message.
                  ^^^^^^^
   Error: Multiple solutions for the implementation
   of vlib  with variants [ "default" ]
-  -> lib2_default ("default")
   -> lib_default ("default")
+  -> lib2_default ("default")
   -> required by executable bar in dune:2
   [1]
 
@@ -78,3 +78,7 @@ Solving variant ambiguity by specifying a concrete implementation.
   Entering directory 'variant-with-concrete-impl'
            bar alias default
   hello from lib2.default
+
+Don't fail when the same library is defined in multiple scopes.
+  $ dune build --root same-lib-in-multiple-scopes
+  Entering directory 'same-lib-in-multiple-scopes'

test/blackbox-tests/test-cases/variants/same-lib-in-multiple-scopes/dune

@@ -0,0 +1,9 @@
+(executable
+  (name exe)
+  (variants unix)
+  (libraries test))
+
+(alias
+ (name default)
+ (action
+  (run ./exe.exe)))

test/blackbox-tests/test-cases/variants/same-lib-in-multiple-scopes/dune-project

@@ -0,0 +1 @@
+(lang dune 1.9)

test/blackbox-tests/test-cases/variants/same-lib-in-multiple-scopes/test/dune-project

@@ -0,0 +1 @@
+(lang dune 1.9)

test/blackbox-tests/test-cases/variants/same-lib-in-multiple-scopes/test/unix/dune

@@ -0,0 +1,5 @@
+(library
+  (name test_unix)
+  (public_name test-unix)
+  (implements test)
+  (variant unix))

test/blackbox-tests/test-cases/variants/same-lib-in-multiple-scopes/test/virt/dune

@@ -0,0 +1,4 @@
+(library
+  (name test)
+  (public_name test)
+  (virtual_modules foo))