perlfunc: Add caveat about string eval containing NV scalar

1 files changed, 8 insertions, 1 deletions

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index 2e603cabc4..4562b2c905 100644
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -1777,7 +1777,8 @@ X<error, handling> X<exception, handling>
 
 =for Pod::Functions catch exceptions or compile and run code
 
-In the first form, the return value of EXPR is parsed and executed as if it
+In the first form, often referred to as a "string eval", the return
+value of EXPR is parsed and executed as if it
 were a little Perl program.  The value of the expression (which is itself
 determined within scalar context) is first parsed, and if there were no
 errors, executed as a block within the lexical context of the current Perl
@@ -1800,6 +1801,12 @@ scope that is still compiling.  See also the L</evalbytes> keyword, which
 always treats its input as a byte stream and works properly with source
 filters, and the L<feature> pragma.
 
+Problems can arise if the string expands a scalar containing a floating
+point number.  That scalar can expand to letters, such as C<"NaN"> or
+C<"Infinity">; or, within the scope of a C<use locale>, the decimal
+point character may be something other than a dot (such as a comma).
+None of these are likely to parse as you are likely expecting.
+
 In the second form, the code within the BLOCK is parsed only once--at the
 same time the code surrounding the C<eval> itself was parsed--and executed
 within the context of the current Perl program.  This form is typically