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Type of '<variablename>' cannot be inferred from an expression containing '<variablename>'

The compiler cannot infer the data type of a variable if the variable is used in establishing its initial value in the declaration.

For example, with Option Infer set to On, the following examples do not compile:

  • Declarations

    ' Does not compile with Option Infer on.  
Dim m = m  
Dim d = someFunction(d)

  • For loop

    ' Does not compile with Option Infer on.  
For j = 1 To j  
Next

  • For Each loop

    ' Does not compile with Option Infer on.  
For Each customer In customer.Orders  
Next

Error ID: BC30980

To correct this error

  • If the two variables were intended to refer to different values, change the name of the variable that you are declaring.

  • Use a literal value instead of the variable name in the initial value, on the right side of the assignment.

  • Use an As clause to specify the type of the variable you are declaring.

See also