ClangCodeModel: Show only valid applicable overloads when completing

libclang is smart enough to filter the overloads according to which
arguments have already been entered, so let's make use of that.

Fixes: QTCREATORBUG-650
Change-Id: Ic2711f460c908c6fd9c8efe28c3c63a0ce2d9205
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/clangcodemodel/clangcompletioncontextanalyzer.cpp

@@ -183,11 +183,8 @@ void ClangCompletionContextAnalyzer::handleFunctionCall(int afterOperatorPositio
             const int functionNameStart = startOfFunctionCall(afterOperatorPosition);
             if (functionNameStart >= 0) {
                 m_addSnippets = functionNameStart == afterOperatorPosition;
-                // Always pass the position right after '(' to libclang because
-                // positions after the comma might be problematic if a preceding
-                // argument is invalid code.
                 setActionAndClangPosition(PassThroughToLibClangAfterLeftParen,
-                                          m_positionForProposal,
+                                          afterOperatorPosition,
                                           functionNameStart);
             } else { // e.g. "(" without any function name in front
                 m_addSnippets = true;

src/plugins/clangcodemodel/test/clangcodecompletion_test.cpp

@@ -608,6 +608,18 @@ void ClangCodeCompletionTest::testCompleteFunctions()
     QVERIFY(hasItem(t.proposal, "TType<QString> f(bool)"));
 }
 
+void ClangCodeCompletionTest::testCompleteOverloads()
+{
+    ProjectLessCompletionTest t("functionCompletionFiltered.cpp");
+    QCOMPARE(t.proposal->size(), 1);
+    QVERIFY(hasItem(t.proposal, "void func(int i, int j)"));
+
+    ProjectLessCompletionTest t2("functionCompletionFiltered2.cpp");
+    QCOMPARE(t2.proposal->size(), 2);
+    QVERIFY(hasItem(t2.proposal, "void func(const S &s, int j)"));
+    QVERIFY(hasItem(t2.proposal, "void func(const S &s, int j, int k)"));
+}
+
 void ClangCodeCompletionTest::testCompleteConstructor()
 {
     ProjectLessCompletionTest t("constructorCompletion.cpp");

src/plugins/clangcodemodel/test/clangcodecompletion_test.h

@@ -48,6 +48,7 @@ private slots:
     void testCompleteMembersFromOutside();
     void testCompleteMembersFromFriend();
     void testCompleteFunctions();
+    void testCompleteOverloads();
     void testCompleteConstructor();
     void testCompleteClassAndConstructor();
 

src/plugins/clangcodemodel/test/data/clangtestdata.qrc

@@ -27,5 +27,7 @@
         <file>membercompletion-outside.cpp</file>
         <file>membercompletion-inside.cpp</file>
         <file>membercompletion-friend.cpp</file>
+        <file>functionCompletionFiltered.cpp</file>
+        <file>functionCompletionFiltered2.cpp</file>
     </qresource>
 </RCC>

src/plugins/clangcodemodel/test/data/functionCompletionFiltered.cpp

@@ -0,0 +1,9 @@
+struct S;
+void func(int i, int j);
+void func(const S &s, int j);
+void func(const S &s, int j, int k);
+
+void g()
+{
+    func(1, /* COMPLETE HERE */
+}

src/plugins/clangcodemodel/test/data/functionCompletionFiltered2.cpp

@@ -0,0 +1,9 @@
+struct S {};
+void func(int i, int j);
+void func(const S &s, int j);
+void func(const S &s, int j, int k);
+
+void g()
+{
+    func(S(), /* COMPLETE HERE */
+}

tests/unit/unittest/clangcompletioncontextanalyzer-test.cpp

@@ -261,14 +261,14 @@ TEST_F(ClangCompletionContextAnalyzer, ArgumentTwoAtCall)
 {
     auto analyzer = runAnalyzer("f(1,@");
 
-    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, -2, -2, positionInText, false));
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, -2, positionInText, false));
 }
 
 TEST_F(ClangCompletionContextAnalyzer, ArgumentTwoWithSpaceAtCall)
 {
     auto analyzer = runAnalyzer("f(1, @");
 
-    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, -3, -3, positionInText, false));
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, -3, positionInText, false));
 }
 
 TEST_F(ClangCompletionContextAnalyzer, WhitespaceAfterFunctionName)
@@ -289,7 +289,7 @@ TEST_F(ClangCompletionContextAnalyzer, ArgumentTwoWithSpaceAtConstructorCallWith
 {
     auto analyzer = runAnalyzer("f{1, @");
 
-    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, -3, -3, positionInText, false));
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, -3, positionInText, false));
 }
 
 TEST_F(ClangCompletionContextAnalyzer, WhitespaceBeforeConstructorCallWithBraceInitializer)
@@ -546,7 +546,7 @@ TEST_F(ClangCompletionContextAnalyzer, TemplatedFunctionSecondArgument)
 {
     auto analyzer = runAnalyzer("f < decltype(bar -> member) > (1, @");
 
-    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, -3, -3, positionInText, false));
+    ASSERT_THAT(analyzer, HasResult(CCA::PassThroughToLibClangAfterLeftParen, 0, -3, positionInText, false));
 }
 
 TEST_F(ClangCompletionContextAnalyzer, FunctionNameStartPosition)