also consider non-implicit locals when checking...

also consider non-implicit locals when checking shadowing of implicits:
closes #3453

nonImplicitSynonymInScope implements the predicate that is used in
tryImplicit's checks for shadowing of locally defined implicits

benchmarking shows the predicate does not significantly affect quick.comp+quick.lib (goes from 11min to 11min2s on my machine -- no optimisations)

review by odersky

1 files changed, 66 insertions, 0 deletions

diff --git a/test/files/neg/t3453.scala b/test/files/neg/t3453.scala
new file mode 100644
index 0000000000..090b777151
--- /dev/null
+++ b/test/files/neg/t3453.scala
@@ -0,0 +1,66 @@
+// test shadowing of implicits by synonymous non-implicit symbols
+// whether they be inherited, imported (explicitly or using a wildcard) or defined directly
+class A
+class B
+
+trait S {
+    implicit def aToB(a: A): B = new B
+}
+
+class T1 extends S {
+    def x: B = {
+        val aToB = 3
+        // ok: doesn't compile, because aToB method requires 'T.this.' prefix
+        //aToB(new A)
+
+        // bug: compiles, using T.this.aToB,
+        //   despite it not being accessible without a prefix
+        new A
+    }
+}
+
+object O {
+    implicit def aToB(a: A): B = new B
+}
+
+class T2a {
+    import O._
+
+    def x: B = {
+        val aToB = 3
+        // ok: doesn't compile, because aToB method requires 'T.this.' prefix
+        //aToB(new A)
+
+        // bug: compiles, using T.this.aToB,
+        //   despite it not being accessible without a prefix
+        new A
+    }
+}
+
+class T2b {
+    import O.aToB
+
+    def x: B = {
+        val aToB = 3
+        // ok: doesn't compile, because aToB method requires 'T.this.' prefix
+        //aToB(new A)
+
+        // bug: compiles, using T.this.aToB,
+        //   despite it not being accessible without a prefix
+        new A
+    }
+}
+
+class T3 {
+    implicit def aToB(a: A): B = new B
+
+    def x: B = {
+        val aToB = 3
+        // ok: doesn't compile, because aToB method requires 'T.this.' prefix
+        //aToB(new A)
+
+        // bug: compiles, using T.this.aToB,
+        //   despite it not being accessible without a prefix
+        new A
+    }
+}
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