Fix a race condition diagnosed by gcc -Wsequence-point (Bug#8254).

An expression of the form (DOWNCASE (x) == DOWNCASE (y)), found in
dired.c's scmp function, had undefined behavior.
* lisp.h (DOWNCASE_TABLE, UPCASE_TABLE, DOWNCASE, UPPERCASEP):
(NOCASEP, LOWERCASEP, UPCASE, UPCASE1): Move from here ...
* buffer.h: ... to here, because these macros use current_buffer,
and the new implementation with inline functions needs to have
current_buffer in scope now, rather than later when the macros
are used.
(downcase, upcase1): New static inline functions.
(DOWNCASE, UPCASE1): Reimplement using these functions.
This avoids undefined behavior in expressions like
DOWNCASE (x) == DOWNCASE (y), which previously suffered
from race conditions in accessing the global variables
case_temp1 and case_temp2.
* casetab.c (case_temp1, case_temp2): Remove; no longer needed.
* lisp.h (case_temp1, case_temp2): Remove their decls.
* character.h (ASCII_CHAR_P): Move from here ...
* lisp.h: ... to here, so that the inline functions mentioned
above can use them.

1 files changed, 43 insertions, 0 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 0975d2e3adc..996e4e59c27 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1026,4 +1026,47 @@ extern int last_per_buffer_idx;
 
 #define PER_BUFFER_VALUE(BUFFER, OFFSET) \
       (*(Lisp_Object *)((OFFSET) + (char *) (BUFFER)))
+
+/* Current buffer's map from characters to lower-case characters.  */
+
+#define DOWNCASE_TABLE BVAR (current_buffer, downcase_table)
+
+/* Current buffer's map from characters to upper-case characters.  */
+
+#define UPCASE_TABLE BVAR (current_buffer, upcase_table)
+
+/* Downcase a character, or make no change if that cannot be done.  */
+
+static inline EMACS_INT
+downcase (int ch)
+{
+  Lisp_Object down = CHAR_TABLE_REF (DOWNCASE_TABLE, ch);
+  return NATNUMP (down) ? XFASTINT (down) : ch;
+}
+#define DOWNCASE(CH) downcase (CH)
+
+/* 1 if CH is upper case.  */
+
+#define UPPERCASEP(CH) (DOWNCASE (CH) != (CH))
 
+/* 1 if CH is neither upper nor lower case.  */
+
+#define NOCASEP(CH) (UPCASE1 (CH) == (CH))
+
+/* 1 if CH is lower case.  */
+
+#define LOWERCASEP(CH) (!UPPERCASEP (CH) && !NOCASEP(CH))
+
+/* Upcase a character, or make no change if that cannot be done.  */
+
+#define UPCASE(CH) (!UPPERCASEP (CH) ? UPCASE1 (CH) : (CH))
+
+/* Upcase a character known to be not upper case.  */
+
+static inline EMACS_INT
+upcase1 (int ch)
+{
+  Lisp_Object up = CHAR_TABLE_REF (UPCASE_TABLE, ch);
+  return NATNUMP (up) ? XFASTINT (up) : ch;
+}
+#define UPCASE1(CH) upcase1 (CH)