Fix CA1854

Author: slozier

Src/DLR

@@ -88,8 +88,8 @@ fully qualified (dotted) module name. It returns the imported
             )]
         public object load_module(CodeContext /*!*/ context, string fullname) {
             var modules = context.LanguageContext.SystemStateModules;
-            if (modules.ContainsKey(fullname))
-                return modules[fullname];
+            if (modules.TryGetValue(fullname, out var module))
+                return module;
 
             bool ispackage;
             string modpath;

Src/IronPython.Modules/ResourceMetaPathImporter.cs

@@ -285,10 +285,9 @@ public static Dialect Create(CodeContext/*!*/ context,
                 kwArgs.TryGetValue("strict", out strict);
 
                 if (dialect != null) {
-                    if (dialect is string) {
-                        string dialectName = (string)dialect;
-                        if (dialects.ContainsKey(dialectName))
-                            dialect = dialects[dialectName];
+                    if (dialect is string dialectName) {
+                        if (dialects.TryGetValue(dialectName, out var value))
+                            dialect = value;
                         else
                             throw MakeError("unknown dialect");
                     }

Src/IronPython.Modules/_csv.cs

@@ -1062,8 +1062,8 @@ static string ApplyVerbose(string pattern) {
                                                     if (tmpIndex == -1) throw PythonExceptions.CreateThrowable(error(context), "unexpected end of regex");
 
                                                     var namedGroup = pattern.Substring(nameIndex + 2, tmpIndex - (nameIndex + 2));
-                                                    if (namedGroups.ContainsKey(namedGroup)) {
-                                                        throw PythonExceptions.CreateThrowable(error(context), $"redefinition of group name '{namedGroup}' as group {groupCount}; was group {namedGroups[namedGroup]}");
+                                                    if (namedGroups.TryGetValue(namedGroup, out var value)) {
+                                                        throw PythonExceptions.CreateThrowable(error(context), $"redefinition of group name '{namedGroup}' as group {groupCount}; was group {value}");
                                                     }
 
                                                     namedGroups[namedGroup] = groupCount;

Src/IronPython.Modules/re.cs

@@ -205,23 +205,24 @@ protected override void ParseArgument(string/*!*/ arg) {
         }
 
         protected override void HandleImplementationSpecificOption(string arg, string val) {
+            object frames;
             switch (arg) {
                 case "NoFrames":
-                    if (LanguageSetup.Options.ContainsKey("Frames") && LanguageSetup.Options["Frames"] != ScriptingRuntimeHelpers.False) {
+                    if (LanguageSetup.Options.TryGetValue("Frames", out frames) && frames != ScriptingRuntimeHelpers.False) {
                         throw new InvalidOptionException("Only one of -X [Full]Frames/NoFrames may be specified");
                     }
                     LanguageSetup.Options["Frames"] = ScriptingRuntimeHelpers.False;
                     break;
 
                 case "Frames":
-                    if (LanguageSetup.Options.ContainsKey("Frames") && LanguageSetup.Options["Frames"] != ScriptingRuntimeHelpers.True) {
+                    if (LanguageSetup.Options.TryGetValue("Frames", out frames) && frames != ScriptingRuntimeHelpers.True) {
                         throw new InvalidOptionException("Only one of -X [Full]Frames/NoFrames may be specified");
                     }
                     LanguageSetup.Options["Frames"] = ScriptingRuntimeHelpers.True;
                     break;
 
                 case "FullFrames":
-                    if (LanguageSetup.Options.ContainsKey("Frames") && LanguageSetup.Options["Frames"] != ScriptingRuntimeHelpers.True) {
+                    if (LanguageSetup.Options.TryGetValue("Frames", out frames) && frames != ScriptingRuntimeHelpers.True) {
                         throw new InvalidOptionException("Only one of -X [Full]Frames/NoFrames may be specified");
                     }
                     LanguageSetup.Options["Frames"] = LanguageSetup.Options["FullFrames"] = ScriptingRuntimeHelpers.True;

Src/IronPython/Hosting/PythonOptionsParser.cs

@@ -148,15 +148,15 @@ private static string GetIronPythonPath() {
             return string.Empty;
         }
 
-        private string ReplaceVariables(string input, IDictionary<string, string> replacements) {
+        private string ReplaceVariables(string input, Dictionary<string, string> replacements) {
             Regex variableRegex = new Regex(@"\$\(([^}]+)\)", RegexOptions.Compiled);
 
             var result = input;
             var match = variableRegex.Match(input);
             while (match.Success) {
                 var variable = match.Groups[1].Value;
-                if (replacements.ContainsKey(variable)) {
-                    result = result.Replace(match.Groups[0].Value, replacements[variable]);
+                if (replacements.TryGetValue(variable, out var replacement)) {
+                    result = result.Replace(match.Groups[0].Value, replacement);
                 }
                 match = match.NextMatch();
             }