Fix logic errors in AvoidAlias rule

The first fix is that after the yield return, we should move on to the next command
The second fix is that if we find _any_ command, we should not move on to the 'Get-<command>' variant
These changes mean that we do not run a pipeline (twice!) to find something that was a cache miss. In the pathological case of a script mmade up of only unique aliases, we would run 2 pipelines for each found alias.

Author: JamesWTruher

Rules/AvoidAlias.cs

@@ -126,25 +126,29 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
                         fileName,
                         commandName,
                         suggestedCorrections: GetCorrectionExtent(cmdAst, cmdletNameIfCommandNameWasAlias));
+                    // do not continue the search, but go to the next command
+                    continue;
+                }
+
+                // If we find match of any kind, do not continue with the Get-{commandname} check
+                if ( Helper.Instance.GetCommandInfo(commandName) != null ) {
+                    continue;
                 }
 
-                var isNativeCommand = Helper.Instance.GetCommandInfo(commandName, CommandTypes.Application | CommandTypes.ExternalScript) != null;
-                if (!isNativeCommand)
+                var commdNameWithGetPrefix = $"Get-{commandName}";
+                var cmdletNameIfCommandWasMissingGetPrefix = Helper.Instance.GetCommandInfo($"Get-{commandName}");
+                if (cmdletNameIfCommandWasMissingGetPrefix != null)
                 {
-                    var commdNameWithGetPrefix = $"Get-{commandName}";
-                    var cmdletNameIfCommandWasMissingGetPrefix = Helper.Instance.GetCommandInfo($"Get-{commandName}");
-                    if (cmdletNameIfCommandWasMissingGetPrefix != null)
-                    {
-                        yield return new DiagnosticRecord(
-                            string.Format(CultureInfo.CurrentCulture, Strings.AvoidUsingCmdletAliasesMissingGetPrefixError, commandName, commdNameWithGetPrefix),
-                            GetCommandExtent(cmdAst),
-                            GetName(),
-                            DiagnosticSeverity.Warning,
-                            fileName,
-                            commandName,
-                            suggestedCorrections: GetCorrectionExtent(cmdAst, commdNameWithGetPrefix));
-                    }
+                    yield return new DiagnosticRecord(
+                        string.Format(CultureInfo.CurrentCulture, Strings.AvoidUsingCmdletAliasesMissingGetPrefixError, commandName, commdNameWithGetPrefix),
+                        GetCommandExtent(cmdAst),
+                        GetName(),
+                        DiagnosticSeverity.Warning,
+                        fileName,
+                        commandName,
+                        suggestedCorrections: GetCorrectionExtent(cmdAst, commdNameWithGetPrefix));
                 }
+
             }
         }
 
@@ -264,4 +268,4 @@ public string GetSourceName()
             return string.Format(CultureInfo.CurrentCulture, Strings.SourceName);
         }
     }
-}
+}