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master 8bb8cc5b49 1/2: Fix condition-case body for-effect miscompilation
From: |
Mattias Engdegård |
Subject: |
master 8bb8cc5b49 1/2: Fix condition-case body for-effect miscompilation |
Date: |
Sat, 24 Dec 2022 06:15:06 -0500 (EST) |
branch: master
commit 8bb8cc5b49a0cb681327ce9abe38266d5e26d19c
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>
Fix condition-case body for-effect miscompilation
(condition-case x A (:success B)) should not compile A for-effect even
if the entire form is in for-effect context.
* lisp/emacs-lisp/byte-opt.el (byte-optimize-form-code-walker):
Don't optimise the condition-case body form for effect (potentially
discarding its value) if there is a success handler and a variable.
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-tests--test-cases):
Add test cases.
---
lisp/emacs-lisp/byte-opt.el | 5 +++-
test/lisp/emacs-lisp/bytecomp-tests.el | 48 ++++++++++++++++++++++++++++++++++
2 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 898dfffef6..ab35b0dde8 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -410,7 +410,10 @@ for speeding up processing.")
(`(condition-case ,var ,exp . ,clauses)
`(,fn ,var ;Not evaluated.
- ,(byte-optimize-form exp for-effect)
+ ,(byte-optimize-form exp
+ (if (assq :success clauses)
+ (null var)
+ for-effect))
,@(mapcar (lambda (clause)
(let ((byte-optimize--lexvars
(and lexical-binding
diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el
b/test/lisp/emacs-lisp/bytecomp-tests.el
index 3400128759..36f541e867 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -704,6 +704,54 @@ inner loops respectively."
(let ((bytecomp-tests--xx 1))
(set (make-local-variable 'bytecomp-tests--xx) 2)
bytecomp-tests--xx)
+
+ ;; Check for-effect optimisation of `condition-case' body form.
+ ;; With `condition-case' in for-effect context:
+ (let ((x (bytecomp-test-identity ?A))
+ (r nil))
+ (condition-case e
+ (characterp x) ; value (:success, var)
+ (error (setq r 'bad))
+ (:success (setq r (list 'good e))))
+ r)
+ (let ((x (bytecomp-test-identity ?B))
+ (r nil))
+ (condition-case nil
+ (characterp x) ; for-effect (:success, no var)
+ (error (setq r 'bad))
+ (:success (setq r 'good)))
+ r)
+ (let ((x (bytecomp-test-identity ?C))
+ (r nil))
+ (condition-case e
+ (characterp x) ; for-effect (no :success, var)
+ (error (setq r (list 'bad e))))
+ r)
+ (let ((x (bytecomp-test-identity ?D))
+ (r nil))
+ (condition-case nil
+ (characterp x) ; for-effect (no :success, no var)
+ (error (setq r 'bad)))
+ r)
+ ;; With `condition-case' in value context:
+ (let ((x (bytecomp-test-identity ?E)))
+ (condition-case e
+ (characterp x) ; for-effect (:success, var)
+ (error (list 'bad e))
+ (:success (list 'good e))))
+ (let ((x (bytecomp-test-identity ?F)))
+ (condition-case nil
+ (characterp x) ; for-effect (:success, no var)
+ (error 'bad)
+ (:success 'good)))
+ (let ((x (bytecomp-test-identity ?G)))
+ (condition-case e
+ (characterp x) ; value (no :success, var)
+ (error (list 'bad e))))
+ (let ((x (bytecomp-test-identity ?H)))
+ (condition-case nil
+ (characterp x) ; value (no :success, no var)
+ (error 'bad)))
)
"List of expressions for cross-testing interpreted and compiled code.")