re PR fortran/39171 (Misleading warning for negative character length)

2010-02-09  Daniel Kraft  <d@domob.eu>

	PR fortran/39171
	* resolve.c (resolve_charlen): Change warning about negative CHARACTER
	length to be correct and issue only with -Wsurprising.
	* invoke.texi (Wsurprising): Mention this new warning that is
	turned on by -Wsurprising.

2010-02-09  Daniel Kraft  <d@domob.eu>

	PR fortran/39171
	* gfortran.dg/char_length_2.f90: Change warning expectations accordingly
	and pass -Wsurprising as necessary.

From-SVN: r156620

gcc/fortran/ChangeLog

 2010-02-09  Daniel Kraft  <d@domob.eu>
 
+	PR fortran/39171
+	* resolve.c (resolve_charlen): Change warning about negative CHARACTER
+	length to be correct and issue only with -Wsurprising.
+	* invoke.texi (Wsurprising): Mention this new warning that is
+	turned on by -Wsurprising.
+
+2010-02-09  Daniel Kraft  <d@domob.eu>
+
 	PR fortran/41507
 	* intrinsic.texi (MAXVAL): Remove wrong claim that array argument
 	can be CHARACTER type.

gcc/fortran/invoke.texi

@@ -792,6 +792,9 @@ A TRANSFER specifies a source that is shorter than the destination.
 @item
 The type of a function result is declared more than once with the same type.  If
 @option{-pedantic} or standard-conforming mode is enabled, this is an error.
+
+@item
+A @code{CHARACTER} variable is declared with negative length.
 @end itemize
 
 @item -Wtabs

gcc/fortran/resolve.c

@@ -8559,8 +8559,10 @@ resolve_charlen (gfc_charlen *cl)
      value, the length of character entities declared is zero."  */
   if (cl->length && !gfc_extract_int (cl->length, &i) && i < 0)
     {
-      gfc_warning_now ("CHARACTER variable has zero length at %L",
-		       &cl->length->where);
+      if (gfc_option.warn_surprising)
+	gfc_warning_now ("CHARACTER variable at %L has negative length %d,"
+			 " the length has been set to zero",
+			 &cl->length->where, i);
       gfc_replace_expr (cl->length, gfc_int_expr (0));
     }
 

gcc/testsuite/ChangeLog

+2010-02-09  Daniel Kraft  <d@domob.eu>
+
+	PR fortran/39171
+	* gfortran.dg/char_length_2.f90: Change warning expectations accordingly
+	and pass -Wsurprising as necessary.
+
 2010-02-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/42890

gcc/testsuite/gfortran.dg/char_length_2.f90

 ! { dg-do link }
+! { dg-options "-Wsurprising" }
 ! Tests the fix for PR 31250
 ! CHARACTER lengths weren't reduced early enough for all checks of
 ! them to be meaningful.  Furthermore negative string lengths weren't
 ! dealt with correctly.
 CHARACTER(len=0) :: c1   ! This is OK.
-CHARACTER(len=-1) :: c2  ! { dg-warning "CHARACTER variable has zero length" }
+CHARACTER(len=-1) :: c2  ! { dg-warning "has negative length" }
 PARAMETER(I=-100)
-CHARACTER(len=I) :: c3   ! { dg-warning "CHARACTER variable has zero length" }
-CHARACTER(len=min(I,500)) :: c4  ! { dg-warning "CHARACTER variable has zero length" }
+CHARACTER(len=I) :: c3   ! { dg-warning "has negative length" }
+CHARACTER(len=min(I,500)) :: c4  ! { dg-warning "has negative length" }
 CHARACTER(len=max(I,500)) :: d1  ! no warning
 CHARACTER(len=5) :: d2   ! no warning