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/Zc:templateScope (Check template parameter shadowing)

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The /Zc:templateScope compiler option enables checks for Standard C++ behavior around shadowing of template parameters.

Syntax

/Zc:templateScope[-]

Remarks

The C++ Standard doesn't allow the reuse of a template parameter's name (or shadowing) for another declaration within the scope of the template. The /Zc:templateScope compiler option enables an error check for such shadowing.

The /Zc:templateScope option is new in Visual Studio 2022 version 17.5 preview 1. The option is off by default even when the code is compiled using the /permissive- option (or an option that implies /permissive-, such as /std:c++20 or /std:c++latest). To enable the error check, you must explicitly add /Zc:templateScope to the compiler command line. To explicitly disable the check, use the /Zc:templateScope- option.

Example

Under /Zc:templateScope, this sample code produces an error:

template<typename T>
void f(T&& t) {
    int T = 13;
}

/* Output:
t.cpp(3): error C7527: 'T': a template parameter name cannot be reused within its scope
*/

To set this compiler option in Visual Studio

  1. Open the project's Property Pages dialog box. For details, see Set C++ compiler and build properties in Visual Studio.

  2. Select the Configuration Properties > C/C++ > Command Line property page.

  3. In Additional options, add /Zc:templateScope or /Zc:templateScope-. Choose OK or Apply to save your changes.

See also

/Zc (Conformance)
/permissive-
/std (Specify language standard version)