The syntax of the declare target directive takes either of the following forms:  

 
#pragma omp declare target new-line 
declaration-definition-seq 
#pragma omp end declare target new-line
  

or  

 
#pragma omp declare target (extended-list) new-line
  

or  

 
#pragma omp declare target clause[ [,] clause ... ] new-line
  

where clause is one of the following:  

 
to(extended-list) 
link(list) 
device_type(host | nohost | any)
       

The syntax of the declare target directive is as follows:  

 
!$omp declare target (extended-list)
  

or  

 
!$omp declare target [clause[ [,] clause] ... ]
  

where clause is one of the following:  

 
to(extended-list) 
link(list) 
device_type(host | nohost | any)
       

If a function appears in a to clause in the same translation unit in which the definition of the function occurs then a device-specific version of the function is created.

If a variable appears in a to clause in the same translation unit in which the definition of the variable occurs then the original list item is allocated a corresponding list item in the device data environment of all devices.

If an internal procedure appears in a to clause then a device-specific version of the procedure is created.

If a variable that is host associated appears in a to clause then the original list item is allocated a corresponding list item in the device data environment of all devices.

If a function is referenced in a function that appears as a list item in a to clause on a declare target directive then the name of the referenced function is treated as if it had appeared in a to clause on a declare target directive.

If a variable with static storage duration or a function (except lambda for C++) is referenced in the initializer expression list of a variable with static storage duration that appears as a list item in a to clause on a declare target directive then the name of the referenced variable or function is treated as if it had appeared in a to clause on a declare target directive.

The form of the declare target directive that has no clauses and requires a matching end declare target directive defines an implicit extended-list to an implicit to clause. The implicit extended-list consists of the variable names of any variable declarations at file or namespace scope that appear between the two directives and of the function names of any function declarations at file, namespace or class scope that appear between the two directives.

The declaration-definition-seq defined by a declare target directive and an end declare target directive may contain declare target directives. If a device_type clause is present on the contained declare target directive, then its argument determines which versions are made available. If a list item appears both in an implicit and explicit list, the explicit list determines which versions are made available.

If a procedure is referenced in a procedure that appears as a list item in a to clause on a declare target directive then the name of the procedure is treated as if it had appeared in a to clause on a declare target directive.

If a declare target does not have any clauses then an implicit extended-list to an implicit to clause of one item is formed from the name of the enclosing subroutine subprogram, function subprogram or interface body to which it applies.

If a declare target directive has a device_type clause then any enclosed internal procedures cannot contain any declare target directives. The enclosing device_type clause implicitly applies to internal procedures.

• The function names of overloaded functions or template functions may only be specified within an implicit extended-list.
• If a lambda declaration and definition appears between a declare target directive and the matching end declare target directive, all variables that are captured by the lambda expression must also appear in a to clause.

• If a list item is a procedure name, it must not be a generic name, procedure pointer or entry name.
• Any declare target directive with clauses must appear in a specification part of a subroutine subprogram, function subprogram, program or module.
• Any declare target directive without clauses must appear in a specification part of a subroutine subprogram, function subprogram or interface body to which it applies.
• If a declare target directive is specified in an interface block for a procedure, it must match a declare target directive in the definition of the procedure.
• If an external procedure is a type-bound procedure of a derived type and a declare target directive is specified in the definition of the external procedure, such a directive must appear in the interface block that is accessible to the derived type definition.
• If any procedure is declared via a procedure declaration statement that is not in the type-bound procedure part of a derived-type definition, any declare target with the procedure name must appear in the same specification part.
• A variable that is part of another variable (as an array, structure element or type parameter inquiry) cannot appear in a declare target directive.
• The declare target directive must appear in the declaration section of a scoping unit in which the common block or variable is declared.
• If a declare target directive that specifies a common block name appears in one program unit, then such a directive must also appear in every other program unit that contains a COMMON statement that specifies the same name, after the last such COMMON statement in the program unit.
• If a list item is declared with the BIND attribute, the corresponding C entities must also be specified in a declare target directive in the C program.
• A blank common block cannot appear in a declare target directive.
• A variable can only appear in a declare target directive in the scope in which it is declared. It must not be an element of a common block or appear in an EQUIVALENCE statement.
• A variable that appears in a declare target directive must be declared in the Fortran scope of a module or have the SAVE attribute, either explicitly or implicitly.