A weird behaivor of GNU make, please help check it

[chenjun]

GNU make 3.81 & 3.82

=======================
define _gmi_prcp_GenCopyRuleL0
#  $(info You catch me!)
  $2: $1
        @echo "PI_precopy for $2 ..."
endef

all:
        @echo "all.$(eval $(call _gmi_prcp_GenCopyRuleL0,ttt,yyy))"
=======================

It outputs:

===========
You catch me!
t.mk:8: *** prerequisites cannot be defined in command scripts.  Stop.
===========

Two questions:
1. Since the $(info ) line is commented out, why "You catch me!" is
output?
2. Since $(eval ) return empty string, why it can cause "prerequisites
cannot be defined in command scripts" error? What does this error mean?

Thank you in advance.