Merge pull request #5340 from hvitved/csharp/null-checks

C#: Use `is [not] null` throughout in the extractor

Author: hvitved

csharp/autobuilder/Semmle.Autobuild.CSharp/CSharpAutobuilder.cs

@@ -97,21 +97,21 @@ BuildScript IntermediateAttempt(BuildScript s) =>
         /// </summary>
         private CSharpBuildStrategy GetCSharpBuildStrategy()
         {
-            if (Options.BuildCommand != null)
+            if (Options.BuildCommand is not null)
                 return CSharpBuildStrategy.CustomBuildCommand;
 
             if (Options.Buildless)
                 return CSharpBuildStrategy.Buildless;
 
-            if (Options.MsBuildArguments != null
-                || Options.MsBuildConfiguration != null
-                || Options.MsBuildPlatform != null
-                || Options.MsBuildTarget != null)
+            if (Options.MsBuildArguments is not null
+                || Options.MsBuildConfiguration is not null
+                || Options.MsBuildPlatform is not null
+                || Options.MsBuildTarget is not null)
             {
                 return CSharpBuildStrategy.MSBuild;
             }
 
-            if (Options.DotNetArguments != null || Options.DotNetVersion != null)
+            if (Options.DotNetArguments is not null || Options.DotNetVersion is not null)
                 return CSharpBuildStrategy.DotNet;
 
             return CSharpBuildStrategy.Auto;

csharp/autobuilder/Semmle.Autobuild.CSharp/DotNetRule.cs

@@ -27,7 +27,7 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
                     .SelectMany(p => Enumerators.Singleton(p).Concat(p.IncludedProjects))
                     .OfType<Project>()
                     .FirstOrDefault(p => !p.DotNetProject);
-                if (notDotNetProject != null)
+                if (notDotNetProject is not null)
                 {
                     builder.Log(Severity.Info, "Not using .NET Core because of incompatible project {0}", notDotNetProject);
                     return BuildScript.Failure;
@@ -103,7 +103,7 @@ private static BuildScript WithDotNet(Autobuilder builder, Func<string?, IDictio
 
                     if (!compatibleClr)
                     {
-                        if (env == null)
+                        if (env is null)
                             env = new Dictionary<string, string>();
                         env.Add("UseSharedCompilation", "false");
                     }
@@ -266,7 +266,7 @@ private static BuildScript GetInstalledSdksScript(IBuildActions actions)
         }
 
         private static string DotNetCommand(IBuildActions actions, string? dotNetPath) =>
-            dotNetPath != null ? actions.PathCombine(dotNetPath, "dotnet") : "dotnet";
+            dotNetPath is not null ? actions.PathCombine(dotNetPath, "dotnet") : "dotnet";
 
         private static BuildScript GetInfoCommand(IBuildActions actions, string? dotNetPath, IDictionary<string, string>? environment)
         {

csharp/autobuilder/Semmle.Autobuild.CSharp/StandaloneBuildRule.cs

@@ -13,11 +13,11 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
             BuildScript GetCommand(string? solution)
             {
                 string standalone;
-                if (builder.CodeQLExtractorLangRoot is object && builder.CodeQlPlatform is object)
+                if (builder.CodeQLExtractorLangRoot is not null && builder.CodeQlPlatform is not null)
                 {
                     standalone = builder.Actions.PathCombine(builder.CodeQLExtractorLangRoot, "tools", builder.CodeQlPlatform, "Semmle.Extraction.CSharp.Standalone");
                 }
-                else if (builder.SemmlePlatformTools is object)
+                else if (builder.SemmlePlatformTools is not null)
                 {
                     standalone = builder.Actions.PathCombine(builder.SemmlePlatformTools, "csharp", "Semmle.Extraction.CSharp.Standalone");
                 }
@@ -29,7 +29,7 @@ BuildScript GetCommand(string? solution)
                 var cmd = new CommandBuilder(builder.Actions);
                 cmd.RunCommand(standalone);
 
-                if (solution != null)
+                if (solution is not null)
                     cmd.QuoteArgument(solution);
 
                 cmd.Argument("--references:.");

csharp/autobuilder/Semmle.Autobuild.Shared/AutobuildOptions.cs

@@ -59,7 +59,7 @@ public static class OptionsExtensions
     {
         public static bool AsBool(this string? value, string param, bool defaultValue)
         {
-            if (value == null)
+            if (value is null)
                 return defaultValue;
 
             switch (value.ToLower())
@@ -81,7 +81,7 @@ public static bool AsBool(this string? value, string param, bool defaultValue)
 
         public static string[] AsListWithExpandedEnvVars(this string? value, IBuildActions actions, string[] defaultValue)
         {
-            if (value == null)
+            if (value is null)
                 return defaultValue;
 
             return value.

csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs

@@ -176,12 +176,12 @@ protected Autobuilder(IBuildActions actions, AutobuildOptions options)
 
                 // First look for `.proj` files
                 ret = FindFiles(".proj", f => new Project(this, f))?.ToList();
-                if (ret != null)
+                if (ret is not null)
                     return ret;
 
                 // Then look for `.sln` files
                 ret = FindFiles(".sln", f => new Solution(this, f, false))?.ToList();
-                if (ret != null)
+                if (ret is not null)
                     return ret;
 
                 // Finally look for language specific project files, e.g. `.csproj` files

csharp/autobuilder/Semmle.Autobuild.Shared/BuildActions.cs

@@ -157,11 +157,11 @@ private static ProcessStartInfo GetProcessStartInfo(string exe, string arguments
                 UseShellExecute = false,
                 RedirectStandardOutput = redirectStandardOutput
             };
-            if (workingDirectory != null)
+            if (workingDirectory is not null)
                 pi.WorkingDirectory = workingDirectory;
 
             // Environment variables can only be used when not redirecting stdout
-            if (!redirectStandardOutput && environment != null)
+            if (!redirectStandardOutput && environment is not null)
                 environment.ForEach(kvp => pi.Environment[kvp.Key] = kvp.Value);
             return pi;
         }

csharp/autobuilder/Semmle.Autobuild.Shared/BuildCommandAutoRule.cs

@@ -39,7 +39,7 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
             var scripts = buildScripts.SelectMany(s => extensions.Select(e => s + e));
             var scriptPath = builder.Paths.Where(p => scripts.Any(p.Item1.ToLower().EndsWith)).OrderBy(p => p.Item2).Select(p => p.Item1).FirstOrDefault();
 
-            if (scriptPath == null)
+            if (scriptPath is null)
                 return BuildScript.Failure;
 
             var chmod = new CommandBuilder(builder.Actions);
@@ -55,7 +55,7 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
 
                 // A specific Visual Studio version may be required
                 var vsTools = MsBuildRule.GetVcVarsBatFile(builder);
-                if (vsTools != null)
+                if (vsTools is not null)
                     command.CallBatFile(vsTools.Path);
 
                 builder.MaybeIndex(command, scriptPath);

csharp/autobuilder/Semmle.Autobuild.Shared/BuildCommandRule.cs

@@ -14,7 +14,7 @@ public BuildCommandRule(WithDotNet withDotNet)
 
         public BuildScript Analyse(Autobuilder builder, bool auto)
         {
-            if (builder.Options.BuildCommand == null)
+            if (builder.Options.BuildCommand is null)
                 return BuildScript.Failure;
 
             // Custom build commands may require a specific .NET Core version
@@ -24,7 +24,7 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
 
                     // Custom build commands may require a specific Visual Studio version
                     var vsTools = MsBuildRule.GetVcVarsBatFile(builder);
-                    if (vsTools != null)
+                    if (vsTools is not null)
                         command.CallBatFile(vsTools.Path);
                     builder.MaybeIndex(command, builder.Options.BuildCommand);
 

csharp/autobuilder/Semmle.Autobuild.Shared/BuildScript.cs

@@ -150,13 +150,13 @@ public BindBuildScript(BuildScript s1, Func<int, BuildScript> s2)
             public override int Run(IBuildActions actions, Action<string, bool> startCallback, Action<int, string, bool> exitCallBack)
             {
                 int ret1;
-                if (s2a != null)
+                if (s2a is not null)
                 {
                     ret1 = s1.Run(actions, startCallback, exitCallBack, out var stdout1);
                     return s2a(stdout1, ret1).Run(actions, startCallback, exitCallBack);
                 }
 
-                if (s2b != null)
+                if (s2b is not null)
                 {
                     ret1 = s1.Run(actions, startCallback, exitCallBack);
                     return s2b(ret1).Run(actions, startCallback, exitCallBack);
@@ -168,7 +168,7 @@ public override int Run(IBuildActions actions, Action<string, bool> startCallbac
             public override int Run(IBuildActions actions, Action<string, bool> startCallback, Action<int, string, bool> exitCallBack, out IList<string> stdout)
             {
                 var ret1 = s1.Run(actions, startCallback, exitCallBack, out var stdout1);
-                var ret2 = (s2a != null ? s2a(stdout1, ret1) : s2b!(ret1)).Run(actions, startCallback, exitCallBack, out var stdout2);
+                var ret2 = (s2a is not null ? s2a(stdout1, ret1) : s2b!(ret1)).Run(actions, startCallback, exitCallBack, out var stdout2);
                 var @out = new List<string>();
                 @out.AddRange(stdout1);
                 @out.AddRange(stdout2);

csharp/autobuilder/Semmle.Autobuild.Shared/BuildTools.cs

@@ -27,7 +27,7 @@ public static class BuildTools
         public static IEnumerable<VcVarsBatFile> GetCandidateVcVarsFiles(IBuildActions actions)
         {
             var programFilesx86 = actions.GetEnvironmentVariable("ProgramFiles(x86)");
-            if (programFilesx86 == null)
+            if (programFilesx86 is null)
                 yield break;
 
             // Attempt to use vswhere to find installations of Visual Studio