Fix lexing of numbers with trailing decimal point and exponent

Numbers with a trailing dot and an exponent were incorrectly read as
integers (with the exponent ignored) instead of the floats they should
be.  For example, 1.e6 was read as the integer 1, not 1000000.0 as
every sane person would agree was meant. (Bug#48678)

Numbers with a trailing dot but no exponent are still read as
integers.

* src/lread.c (string_to_number): Fix float lexing.
* test/src/lread-tests.el (lread-float): Add test.
* doc/lispref/numbers.texi (Float Basics): Clarify syntax.

diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi
index 4c5f72126ed6e7a48d79fec19ce4a69fc5d33e44..d28e15869aa718c394e96fcc09442400667c200b 100644 (file)
--- a/doc/lispref/numbers.texi
+++ b/doc/lispref/numbers.texi
@@ -237,7 +237,8 @@ precede the number and its exponent.  For example, @samp{1500.0},
 @samp{+15e2}, @samp{15.0e+2}, @samp{+1500000e-3}, and @samp{.15e4} are
 five ways of writing a floating-point number whose value is 1500.
 They are all equivalent.  Like Common Lisp, Emacs Lisp requires at
-least one digit after any decimal point in a floating-point number;
+least one digit after a decimal point in a floating-point number that
+does not have an exponent;
 @samp{1500.} is an integer, not a floating-point number.
 
   Emacs Lisp treats @code{-0.0} as numerically equal to ordinary zero

diff --git a/src/lread.c b/src/lread.c
index bca53a9a37aaeb31540ab633d8e08724c6506625..0b33fd0f25440c17551e26cd5623334dd49d0f56 100644 (file)
--- a/src/lread.c
+++ b/src/lread.c
@@ -3938,8 +3938,7 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
   bool signedp = negative | positive;
   cp += signedp;
 
-  enum { INTOVERFLOW = 1, LEAD_INT = 2, DOT_CHAR = 4, TRAIL_INT = 8,
-        E_EXP = 16 };
+  enum { INTOVERFLOW = 1, LEAD_INT = 2, TRAIL_INT = 4, E_EXP = 16 };
   int state = 0;
   int leading_digit = digit_to_number (*cp, base);
   uintmax_t n = leading_digit;
@@ -3959,7 +3958,6 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
   char const *after_digits = cp;
   if (*cp == '.')
     {
-      state |= DOT_CHAR;
       cp++;
     }
 
@@ -4008,8 +4006,10 @@ string_to_number (char const *string, int base, ptrdiff_t *plen)
            cp = ecp;
        }
 
-      float_syntax = ((state & (DOT_CHAR|TRAIL_INT)) == (DOT_CHAR|TRAIL_INT)
-                     || (state & ~INTOVERFLOW) == (LEAD_INT|E_EXP));
+      /* A float has digits after the dot or an exponent.
+        This excludes numbers like "1." which are lexed as integers. */
+      float_syntax = ((state & TRAIL_INT)
+                     || ((state & LEAD_INT) && (state & E_EXP)));
     }
 
   if (plen)

diff --git a/test/src/lread-tests.el b/test/src/lread-tests.el
index f2a60bcf327db78d3c72aeecc6c7d737be9874c3..dac8f95bc4dd936882261e7e49de0056630724cb 100644 (file)
--- a/test/src/lread-tests.el
+++ b/test/src/lread-tests.el
@@ -196,4 +196,71 @@ literals (Bug#20852)."
     (should-error (read-event "foo: "))
     (should-error (read-char-exclusive "foo: "))))
 
+(ert-deftest lread-float ()
+  (should (equal (read "13") 13))
+  (should (equal (read "+13") 13))
+  (should (equal (read "-13") -13))
+  (should (equal (read "13.") 13))
+  (should (equal (read "+13.") 13))
+  (should (equal (read "-13.") -13))
+  (should (equal (read "13.25") 13.25))
+  (should (equal (read "+13.25") 13.25))
+  (should (equal (read "-13.25") -13.25))
+  (should (equal (read ".25") 0.25))
+  (should (equal (read "+.25") 0.25))
+  (should (equal (read "-.25") -0.25))
+  (should (equal (read "13e4") 130000.0))
+  (should (equal (read "+13e4") 130000.0))
+  (should (equal (read "-13e4") -130000.0))
+  (should (equal (read "13e+4") 130000.0))
+  (should (equal (read "+13e+4") 130000.0))
+  (should (equal (read "-13e+4") -130000.0))
+  (should (equal (read "625e-4") 0.0625))
+  (should (equal (read "+625e-4") 0.0625))
+  (should (equal (read "-625e-4") -0.0625))
+  (should (equal (read "1.25e2") 125.0))
+  (should (equal (read "+1.25e2") 125.0))
+  (should (equal (read "-1.25e2") -125.0))
+  (should (equal (read "1.25e+2") 125.0))
+  (should (equal (read "+1.25e+2") 125.0))
+  (should (equal (read "-1.25e+2") -125.0))
+  (should (equal (read "1.25e-1") 0.125))
+  (should (equal (read "+1.25e-1") 0.125))
+  (should (equal (read "-1.25e-1") -0.125))
+  (should (equal (read "4.e3") 4000.0))
+  (should (equal (read "+4.e3") 4000.0))
+  (should (equal (read "-4.e3") -4000.0))
+  (should (equal (read "4.e+3") 4000.0))
+  (should (equal (read "+4.e+3") 4000.0))
+  (should (equal (read "-4.e+3") -4000.0))
+  (should (equal (read "5.e-1") 0.5))
+  (should (equal (read "+5.e-1") 0.5))
+  (should (equal (read "-5.e-1") -0.5))
+  (should (equal (read "0") 0))
+  (should (equal (read "+0") 0))
+  (should (equal (read "-0") 0))
+  (should (equal (read "0.") 0))
+  (should (equal (read "+0.") 0))
+  (should (equal (read "-0.") 0))
+  (should (equal (read "0.0") 0.0))
+  (should (equal (read "+0.0") 0.0))
+  (should (equal (read "-0.0") -0.0))
+  (should (equal (read "0e5") 0.0))
+  (should (equal (read "+0e5") 0.0))
+  (should (equal (read "-0e5") -0.0))
+  (should (equal (read "0e-5") 0.0))
+  (should (equal (read "+0e-5") 0.0))
+  (should (equal (read "-0e-5") -0.0))
+  (should (equal (read ".0e-5") 0.0))
+  (should (equal (read "+.0e-5") 0.0))
+  (should (equal (read "-.0e-5") -0.0))
+  (should (equal (read "0.0e-5") 0.0))
+  (should (equal (read "+0.0e-5") 0.0))
+  (should (equal (read "-0.0e-5") -0.0))
+  (should (equal (read "0.e-5") 0.0))
+  (should (equal (read "+0.e-5") 0.0))
+  (should (equal (read "-0.e-5") -0.0))
+  )
+
+
 ;;; lread-tests.el ends here