bug in Rf_PrintValue ?

I'm very green with R, so maybe this is not a bug, but it looks like one to
me.  The following program segfaults at the second call to Rf_PrintValue().
 To failure depends on the value of the y-string.  E.g., if I change it from
"coverage" to, say, "COVERAGE", the segfault does not occur.

/* bug.c */
#include <stdio.h>
#include <Rinternals.h>
#include <Rembedded.h>

int main(int argc, char **argv) {
  char *x = "foo";
  char *y = "coverage";
  SEXP x_r, y_r;

  Rf_initEmbeddedR(argc, argv);
  PROTECT( x_r = mkChar( x ) );

  Rf_PrintValue( x_r );
  printf( "OK\n" );

  PROTECT( y_r = mkChar( y ) );
  Rf_PrintValue( y_r );
  printf( "OK\n" );

  UNPROTECT( 2 );
  return 0;
}

I compile this code with:

% env -i PATH=/bin:/usr/bin ./myR/bin/R CMD LINK gcc -g
-I./R-2.9.0/src/include -L./myR/lib64/R/lib -lR -lRblas bug.c -o bug

A run looks like this:

% env -i PATH=/bin:/usr/bin R_HOME=$(./myR/bin/R RHOME) ./bug -q --vanilla
<CHARSXP: "foo">
OK
<CHARSXP: "coverage">

 *** caught segfault ***
address 0x6c6c756e2e8d, cause 'memory not mapped'

Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
Selection: 1
aborting ...
zsh: segmentation fault  env -i PATH=/bin:/usr/bin R_HOME=$(./myR/bin/R
RHOME) ./bug -q --vanilla


I think the problem has to do with the fact that there may already exist a
cached copy of "coverage" .

Regards,

Kynn

PS: Any comments on my code would be very welcome; I'm very much the noob
with all this.

	[[alternative HTML version deleted]]

I'm very green with R, so maybe this is not a bug, but it looks like one to
me.  The following program segfaults at the second call to
Rf_PrintValue().

mkChar creates a CHARSXP. These are not normally user-visible, but
instead are placed into a STRSXP (vector type of 'character' in R). So
you want to

    PROTECT( x_r = allocVector(STRSXP, 1) );
    SET_STRING_ELT(x_r, 0, mkChar( x ));

(There is also mkString( x ) for the special case of constructing
character(1)).

I think the segfault is because the CHARSXP returned by mkChar is
initialized with information different from that expected of
user-visible SEXPs (I think it is the information on chaining the node
to the hash table; see Defn.h:120 and memory.c:2844); I think the
success of Rf_PrintValue on 'foo' is a ghost left over from when
CHARSXPs were user-visible.