Fix new warnings found with CA1854 improvement. (#85613)

* Fix new warnings found with CA1854 improvement

Author: buyaa-n

src/libraries/Microsoft.Extensions.Logging.Abstractions/gen/LoggerMessageGenerator.Emitter.cs

@@ -254,10 +254,10 @@ private void GenCases(LoggerMethod lm, string nestedIndentation)
                 {
                     // this is related to https://github.com/serilog/serilog-extensions-logging/issues/197
                     string name = p.CodeName;
-                    if (lm.TemplateMap.ContainsKey(name))
+                    if (lm.TemplateMap.TryGetValue(name, out string value))
                     {
                         // take the letter casing from the template
-                        name = lm.TemplateMap[name];
+                        name = value;
                     }
 
                     _builder.AppendLine($"                    {nestedIndentation}{index++} => new global::System.Collections.Generic.KeyValuePair<string, object?>(\"{name}\", this.{NormalizeSpecialSymbol(p.CodeName)}),");

src/libraries/System.Net.HttpListener/src/System/Net/Managed/HttpEndPointManager.cs

@@ -135,9 +135,9 @@ private static HttpEndPointListener GetEPListener(string host, int port, HttpLis
             }
 
             Dictionary<int, HttpEndPointListener>? p;
-            if (s_ipEndPoints.ContainsKey(addr))
+            if (s_ipEndPoints.TryGetValue(addr, out Dictionary<int, HttpEndPointListener>? value))
             {
-                p = s_ipEndPoints[addr];
+                p = value;
             }
             else
             {
@@ -146,9 +146,9 @@ private static HttpEndPointListener GetEPListener(string host, int port, HttpLis
             }
 
             HttpEndPointListener? epl;
-            if (p.ContainsKey(port))
+            if (p.TryGetValue(port, out HttpEndPointListener? epListener))
             {
-                epl = p[port];
+                epl = epListener;
             }
             else
             {

src/tools/illink/src/linker/Linker.Dataflow/MethodBodyScanner.cs

@@ -138,8 +138,8 @@ private static void NewKnownStack (Dictionary<int, Stack<StackSlot>> knownStacks
 				return;
 			}
 
-			if (knownStacks.ContainsKey (newOffset)) {
-				knownStacks[newOffset] = MergeStack (knownStacks[newOffset], newStack);
+			if (knownStacks.TryGetValue (newOffset, out Stack<StackSlot>? value)) {
+				knownStacks[newOffset] = MergeStack (value, newStack);
 			} else {
 				knownStacks.Add (newOffset, new Stack<StackSlot> (newStack.Reverse ()));
 			}
@@ -292,12 +292,12 @@ protected virtual void Scan (MethodIL methodIL, ref InterproceduralState interpr
 			foreach (Instruction operation in methodIL.Instructions) {
 				int curBasicBlock = blockIterator.MoveNext (operation);
 
-				if (knownStacks.ContainsKey (operation.Offset)) {
+				if (knownStacks.TryGetValue (operation.Offset, out Stack<StackSlot>? knownValue)) {
 					if (currentStack == null) {
 						// The stack copy constructor reverses the stack
-						currentStack = new Stack<StackSlot> (knownStacks[operation.Offset].Reverse ());
+						currentStack = new Stack<StackSlot> (knownValue.Reverse ());
 					} else {
-						currentStack = MergeStack (currentStack, knownStacks[operation.Offset]);
+						currentStack = MergeStack (currentStack, knownValue);
 					}
 				}