pcre2test: really allow libedit with cmake

Using cmake to configure and enable linking pcre2test with libedit,
could result in a broken build, because the header used was instead
pointing to readline.

In cases were the build will succeed (because both libraries were
available), it would likely show warnings, because several history
functions were being used without declarations, since readline
requires including "history.h" for those.

Additionally, since PCRE2_SUPPORT_READLINE is ON by default (unlike
configure), turning PCRE2_SUPPORT_LIBEDIT=ON, would require setting
that other option to OFF explicitly (even if readline wasn't available)
or the setup would abort.

Lastly, in systems with no default sysroot (ex: macOS), the use of
absolut paths for searching for libedit's readline.h could fail so
use instead relative PATH_SUFFIXES.

CMakeLists.txt

@@ -306,9 +306,15 @@ ENDIF(PCRE2_SUPPORT_LIBZ)
 IF(EDITLINE_FOUND)
   OPTION (PCRE2_SUPPORT_LIBEDIT  "Enable support for linking pcre2test with libedit." OFF)
 ENDIF(EDITLINE_FOUND)
-IF(PCRE2_SUPPORT_LIBEDIT)
-  INCLUDE_DIRECTORIES(${EDITLINE_INCLUDE_DIR})
-ENDIF(PCRE2_SUPPORT_LIBEDIT)
+IF(EDITLINE_FOUND)
+  IF(PCRE2_SUPPORT_LIBEDIT)
+    INCLUDE_DIRECTORIES(${EDITLINE_INCLUDE_DIR})
+  ENDIF(PCRE2_SUPPORT_LIBEDIT)
+ELSE(EDITLINE_FOUND)
+  IF(PCRE2_SUPPORT_LIBEDIT)
+    MESSAGE(FATAL_ERROR "libedit not found, set Editline_ROOT if needed")
+  ENDIF(PCRE2_SUPPORT_LIBEDIT)
+ENDIF(EDITLINE_FOUND)
 
 # readline lib
 IF(READLINE_FOUND)
@@ -346,7 +352,9 @@ IF(PCRE2_BUILD_PCRE2GREP AND NOT PCRE2_BUILD_PCRE2_8)
 ENDIF(PCRE2_BUILD_PCRE2GREP AND NOT PCRE2_BUILD_PCRE2_8)
 
 IF(PCRE2_SUPPORT_LIBREADLINE AND PCRE2_SUPPORT_LIBEDIT)
-        MESSAGE(FATAL_ERROR "Only one of libreadline or libeditline can be specified")
+        IF(READLINE_FOUND)
+                MESSAGE(FATAL_ERROR "Only one of libreadline or libeditline can be enabled at the same time")
+        ENDIF(READLINE_FOUND)
 ENDIF(PCRE2_SUPPORT_LIBREADLINE AND PCRE2_SUPPORT_LIBEDIT)
 
 IF(PCRE2_SUPPORT_BSR_ANYCRLF)

cmake/FindEditline.cmake

@@ -3,10 +3,10 @@
 if(EDITLINE_INCLUDE_DIR AND EDITLINE_LIBRARY AND NCURSES_LIBRARY)
   set(EDITLINE_FOUND TRUE)
 else(EDITLINE_INCLUDE_DIR AND EDITLINE_LIBRARY AND NCURSES_LIBRARY)
-  FIND_PATH(EDITLINE_INCLUDE_DIR readline.h
-    /usr/include/editline
-    /usr/include/edit/readline  
-    /usr/include/readline
+  FIND_PATH(EDITLINE_INCLUDE_DIR readline.h PATH_SUFFIXES
+    editline
+    edit/readline
+    readline
   )
 
   FIND_LIBRARY(EDITLINE_LIBRARY NAMES edit)

src/pcre2test.c

@@ -95,7 +95,7 @@ that first, falling back to readline/readline.h. */
 #if defined(HAVE_EDITLINE_READLINE_H)
 #include <editline/readline.h>
 #else
-#include <readline/readline.h>
+#include <readline.h>
 #endif
 #endif
 #endif