_linters/src/honnef.co/go/tools/ssa/builder.go
func (b *builder) setCallFunc(fn *Function, e *ast.CallExpr, c *CallCommon) {
	c.pos = e.Lparen

	// Is this a method call?
	if selector, ok := unparen(e.Fun).(*ast.SelectorExpr); ok {
		sel, ok := fn.Pkg.info.Selections[selector]
		if ok && sel.Kind() == types.MethodVal {
			obj := sel.Obj().(*types.Func)
			recv := recvType(obj)
			wantAddr := isPointer(recv)
			escaping := true
			v := b.receiver(fn, selector.X, wantAddr, escaping, sel)
			if isInterface(recv) {
				// Invoke-mode call.
				c.Value = v
				c.Method = obj
			} else {
				// "Call"-mode call.
				c.Value = fn.Prog.declaredFunc(obj)
				c.Args = append(c.Args, v)
			}
			return
		}

		// sel.Kind()==MethodExpr indicates T.f() or (*T).f():
		// a statically dispatched call to the method f in the
		// method-set of T or *T.  T may be an interface.
		//
		// e.Fun would evaluate to a concrete method, interface
		// wrapper function, or promotion wrapper.
		//
		// For now, we evaluate it in the usual way.
		//
		// TODO(adonovan): opt: inline expr() here, to make the
		// call static and to avoid generation of wrappers.
		// It's somewhat tricky as it may consume the first
		// actual parameter if the call is "invoke" mode.
		//
		// Examples:
		//  type T struct{}; func (T) f() {}   // "call" mode
		//  type T interface { f() }           // "invoke" mode
		//
		//  type S struct{ T }
		//
		//  var s S
		//  S.f(s)
		//  (*S).f(&s)
		//
		// Suggested approach:
		// - consume the first actual parameter expression
		//   and build it with b.expr().
		// - apply implicit field selections.
		// - use MethodVal logic to populate fields of c.
	}

	// Evaluate the function operand in the usual way.
	c.Value = b.expr(fn, e.Fun)
}
func (b *builder) setCallFunc(fn *Function, e *ast.CallExpr, c *CallCommon) {
	c.pos = e.Lparen

	// Is this a method call?
	if selector, ok := unparen(e.Fun).(*ast.SelectorExpr); ok {
		sel, ok := fn.Pkg.info.Selections[selector]
		if ok && sel.Kind() == types.MethodVal {
			obj := sel.Obj().(*types.Func)
			recv := recvType(obj)
			wantAddr := isPointer(recv)
			escaping := true
			v := b.receiver(fn, selector.X, wantAddr, escaping, sel)
			if isInterface(recv) {
				// Invoke-mode call.
				c.Value = v
				c.Method = obj
			} else {
				// "Call"-mode call.
				c.Value = fn.Prog.declaredFunc(obj)
				c.Args = append(c.Args, v)
			}
			return
		}

		// sel.Kind()==MethodExpr indicates T.f() or (*T).f():
		// a statically dispatched call to the method f in the
		// method-set of T or *T.  T may be an interface.
		//
		// e.Fun would evaluate to a concrete method, interface
		// wrapper function, or promotion wrapper.
		//
		// For now, we evaluate it in the usual way.
		//
		// TODO(adonovan): opt: inline expr() here, to make the
		// call static and to avoid generation of wrappers.
		// It's somewhat tricky as it may consume the first
		// actual parameter if the call is "invoke" mode.
		//
		// Examples:
		//  type T struct{}; func (T) f() {}   // "call" mode
		//  type T interface { f() }           // "invoke" mode
		//
		//  type S struct{ T }
		//
		//  var s S
		//  S.f(s)
		//  (*S).f(&s)
		//
		// Suggested approach:
		// - consume the first actual parameter expression
		//   and build it with b.expr().
		// - apply implicit field selections.
		// - use MethodVal logic to populate fields of c.
	}

	// Evaluate the function operand in the usual way.
	c.Value = b.expr(fn, e.Fun)
}
// setCallFunc populates the function parts of a CallCommon structure
// (Func, Method, Recv, Args[0]) based on the kind of invocation
// occurring in e.
//