LanguageClient: Support limit parameter for completion request

... and make use of it in the ClangCodeModel tests.

Change-Id: Ib2186273aec1db9b354892c2e1c4ebd82e3c1c96
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -167,13 +167,7 @@ static BaseClientInterface *clientInterface(Project *project, const Utils::FileP
         indexingOption += "=0";
     const QString headerInsertionOption = QString("--header-insertion=")
             + (settings.autoIncludeHeaders() ? "iwyu" : "never");
-#ifdef WITH_TESTS
-    // For the #include < test, which needs to get a local header file, but the list
-    // is being flooded with system include headers. 4280 on Windows!
-    const QString limitResults = QString("--limit-results=0");
-#else
     const QString limitResults = QString("--limit-results=%1").arg(settings.completionResults());
-#endif
     Utils::CommandLine cmd{settings.clangdFilePath(),
                            {indexingOption,
                             headerInsertionOption,

src/plugins/clangcodemodel/test/clangdtests.cpp

@@ -1550,6 +1550,9 @@ void ClangdTestCompletion::testCompletePreprocessorKeywords()
 
 void ClangdTestCompletion::testCompleteIncludeDirective()
 {
+    // Our local include is way down in the result list.
+    client()->setCompletionResultsLimit(0);
+
     ProposalModelPtr proposal;
     getProposal("includeDirectiveCompletion.cpp", proposal);
 
@@ -1558,6 +1561,7 @@ void ClangdTestCompletion::testCompleteIncludeDirective()
     QVERIFY(hasItem(proposal, " otherFile.h>"));
     QVERIFY(hasItem(proposal, " mylib/"));
     QVERIFY(!hasSnippet(proposal, "class "));
+    client()->setCompletionResultsLimit(-1);
 }
 
 void ClangdTestCompletion::testCompleteGlobals()