From cb25e1d55aaa9763286b76137444d62b313a553b Mon Sep 17 00:00:00 2001
From: Svetlana Isakova <svetlana.isakova@jetbrains.com>
Date: Thu, 26 Sep 2013 14:41:48 +0400
Subject: [PATCH] if some type parameter has only weak constraints (from
 bounds), then we consider it as unknown

---
 .../upperBounds/doNotInferFromBoundsOnly.kt   | 69 +++++++++++++++++++
 .../checkers/JetDiagnosticsTestGenerated.java |  5 ++
 .../calls/inference/TypeConstraintsImpl.java  |  9 +++
 3 files changed, 83 insertions(+)
 create mode 100644 compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.kt

diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.kt
new file mode 100644
index 00000000000..885438f26c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.kt
@@ -0,0 +1,69 @@
+package a
+
+trait A
+
+fun <T> emptyList(): List<T> = throw Exception()
+
+fun test1() {
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyList<!>()
+}
+
+//--------------
+
+fun <T: A> emptyListOfA(): List<T> = throw Exception()
+
+fun test2() {
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyListOfA<!>()
+}
+
+//--------------
+
+fun <T: A, R: T> emptyStrangeMap(): Map<T, R> = throw Exception()
+
+fun test3() {
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyStrangeMap<!>()
+}
+
+//--------------
+
+fun <T, R: T> emptyStrangeMap1(t: T): Map<T, R> = throw Exception("$t")
+
+fun test4() {
+    //todo we may infer 'Int' for 'R' here
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyStrangeMap1<!>(1)
+}
+
+//--------------
+
+fun <T: A, R: T> emptyStrangeMap2(t: T): Map<T, R> where R: A = throw Exception("$t")
+
+fun test5(a: A) {
+    //todo we may infer 'A' for 'R' here
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyStrangeMap2<!>(a)
+}
+
+//--------------
+
+fun <T: A, R: T> emptyStrangeMap3(r: R): Map<T, R> = throw Exception("$r")
+
+fun test6(a: A) {
+    emptyStrangeMap3(a)
+}
+
+//--------------
+
+fun <T, R: T> emptyStrangeMap4(l: MutableList<T>): Map<T, R> = throw Exception("$l")
+
+fun test7(list: MutableList<Int>) {
+    <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyStrangeMap4<!>(list)
+}
+
+//--------------
+
+fun test7() : Map<A, A> = emptyStrangeMap()
+
+//--------------
+
+fun <U, V: U> foo(): U = throw Exception()
+
+fun test8(): Int = <!TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>foo<!>()
diff --git a/compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java
index 747a6dbf332..9d1ee1736f5 100644
--- a/compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java
@@ -3537,6 +3537,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                     JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.GenerateTests", new File("compiler/testData/diagnostics/tests/inference/upperBounds"), Pattern.compile("^(.+)\\.kt$"), true);
                 }
                 
+                @TestMetadata("doNotInferFromBoundsOnly.kt")
+                public void testDoNotInferFromBoundsOnly() throws Exception {
+                    doTest("compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.kt");
+                }
+                
                 @TestMetadata("kt2856.kt")
                 public void testKt2856() throws Exception {
                     doTest("compiler/testData/diagnostics/tests/inference/upperBounds/kt2856.kt");
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/TypeConstraintsImpl.java b/core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/TypeConstraintsImpl.java
index 1c7c4421095..a32fce90126 100644
--- a/core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/TypeConstraintsImpl.java
+++ b/core/descriptors/src/org/jetbrains/jet/lang/resolve/calls/inference/TypeConstraintsImpl.java
@@ -155,6 +155,15 @@ public class TypeConstraintsImpl implements TypeConstraints {
         if (constraints.isEmpty()) {
             return Collections.emptyList();
         }
+        boolean hasStrongConstraint = ContainerUtil.exists(constraints, new Condition<Constraint>() {
+            @Override
+            public boolean value(Constraint constraint) {
+                return constraint.constraintPosition.isStrong();
+            }
+        });
+        if (!hasStrongConstraint) {
+            return Collections.emptyList();
+        }
 
         Set<JetType> exactBounds = filterBounds(constraints, BoundKind.EXACT_BOUND, values);
         if (exactBounds.size() == 1) {