Overview

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The Meziantou.Framework.FullPath package includes Roslyn analyzers and code fixes for C#. They find the code that handles a FullPath as a string, and replace it with the FullPath members, operators and types. Nothing needs to be installed or configured: the rules are active in every C# project that references the package.

The rules fall into three groups:

Using FullPath members: a Path, Directory or Environment method that has a FullPath equivalent, such as Path.Combine(fullPath, "file.txt") instead of fullPath / "file.txt". Most of these rules have a code fix.
Declaring FullPath instead of string: a method, a property, a variable or a parameter declared as string that only ever holds a FullPath.
Comparisons and checks: comparisons that compare the strings of the paths instead of the paths, and checks for the empty path. Two of these rules are warnings, because the code is likely wrong.

Rules

Id	Description	Severity	Code fix
`MFFP0001`	Use FullPath directly instead of Path.GetFullPath	Info	Yes
`MFFP0002`	Use the right FullPath operand directly	Info	Yes
`MFFP0003`	Use '/' with a FullPath base instead of Path.GetFullPath	Info	Yes
`MFFP0004`	Use '/' operator instead of Path.Combine	Info	Yes
`MFFP0005`	Use FullPath.Name instead of Path.GetFileName	Info	Yes
`MFFP0006`	Use FullPath.NameWithoutExtension instead of Path.GetFileNameWithoutExtension	Info	Yes
`MFFP0007`	Use FullPath.Extension instead of Path.GetExtension	Info	Yes
`MFFP0008`	Use FullPath.Parent instead of Path.GetDirectoryName	Info	Yes
`MFFP0009`	Use FullPath.WithExtension instead of Path.ChangeExtension	Info	Yes
`MFFP0010`	Use FullPath.MakePathRelativeTo instead of Path.GetRelativePath	Info	Yes
`MFFP0011`	Return FullPath instead of string	Info	No
`MFFP0012`	Declare the property as FullPath instead of string	Info	No
`MFFP0013`	Declare the variable as FullPath instead of string	Info	No
`MFFP0014`	Declare the parameter as FullPath instead of string	Info	No
`MFFP0015`	Compare FullPath values instead of their string representation	Warning	No
`MFFP0016`	FullPath.Equals with a string argument is always false	Warning	No
`MFFP0018`	Path.IsPathRooted and Path.IsPathFullyQualified are redundant on a FullPath	Info	Yes
`MFFP0019`	Simplify the FullPath.FromPath call	Info	Yes
`MFFP0020`	Use FullPath.FromFileSystemInfo instead of FullPath.FromPath	Info	Yes
`MFFP0021`	Use FullPath.IsEmpty	Info	Yes
`MFFP0022`	Use FullPath.CreateParentDirectory instead of Directory.CreateDirectory	Info	Yes
`MFFP0023`	Use FullPath.Parent instead of Directory.GetParent	Info	No
`MFFP0024`	Use the FullPath equivalent of Path.GetTempPath or Environment.GetFolderPath	Info	Yes

All the rules are enabled by default. There is no MFFP0017.

How a FullPath is recognized

The rules recognize a FullPath in all the forms that turn it into a string: the implicit conversion, a cast to string, Value, RawValue and ToString(). Path.GetFileName(fullPath), Path.GetFileName(fullPath.Value) and Path.GetFileName(fullPath.ToString()) are all reported, and all fixed to fullPath.Name.

The rules do nothing in a project that does not reference Meziantou.Framework.FullPath, and they skip generated code.

Apply the code fixes

The code fixes are offered by the light bulb of the IDE, like the fixes of the .NET analyzers. Every code fix supports Fix all, in a document, a project or a solution. Some fixes are not offered when they could change the behavior of the code; each rule lists these cases.

A fix often changes the type of an expression from string to FullPath. As FullPath converts implicitly to string, the code still compiles in most cases; once it does, the rules of Declaring FullPath instead of string find the declarations to change next.

Change the severity of a rule

Info rules appear as suggestions in the IDE and do not fail the build. To enforce a rule, raise its severity in the .editorconfig file of the solution, for instance dotnet_diagnostic.MFFP0004.severity = warning. Set it to none to disable a rule.