From: Mattias Engdegård <mattiase@acm.org>
Date: Thu, 20 May 2021 16:26:15 +0000 (+0200)
Subject: Fix lexing of numbers with trailing decimal point and exponent
X-Git-Tag: emacs-28.0.90~2313
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=de45864cf787ce244b0d97e7cf523a6e03743f10;p=emacs.git

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 4c5f72126ed..d28e15869aa 100644
--- 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 bca53a9a37a..0b33fd0f254 100644
--- 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 f2a60bcf327..dac8f95bc4d 100644
--- 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