Module Name: src
Committed By: rillig
Date: Thu Jan 27 10:42:02 UTC 2022
Modified Files:
src/usr.bin/make/unit-tests: varname.mk
Log Message:
tests/make: test hash code collisions of variable names
In HashEntry_KeyEquals, the line 'return false' was not covered by any
tests before. Since it is an edge case that two variable names (or
other keys) have the same 32-bit hash code and still differ, better test
for that edge case explicitly since a bug in this place would be rare
and hard to find.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/usr.bin/make/unit-tests/varname.mk
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/usr.bin/make/unit-tests/varname.mk
diff -u src/usr.bin/make/unit-tests/varname.mk:1.8 src/usr.bin/make/unit-tests/varname.mk:1.9
--- src/usr.bin/make/unit-tests/varname.mk:1.8 Mon Nov 2 22:59:48 2020
+++ src/usr.bin/make/unit-tests/varname.mk Thu Jan 27 10:42:02 2022
@@ -1,4 +1,4 @@
-# $NetBSD: varname.mk,v 1.8 2020/11/02 22:59:48 rillig Exp $
+# $NetBSD: varname.mk,v 1.9 2022/01/27 10:42:02 rillig Exp $
#
# Tests for special variables, such as .MAKE or .PARSEDIR.
# And for variable names in general.
@@ -41,4 +41,46 @@ ${VARNAME}= try3
.MAKEFLAGS: -d0
+# All variable names of a scope are stored in the same hash table, using a
+# simple hash function. Ensure that HashEntry_KeyEquals handles collisions
+# correctly and that the correct variable is looked up. The strings "0x" and
+# "1Y" have the same hash code, as 31 * '0' + 'x' == 31 * '1' + 'Y'.
+V.0x= 0x
+V.1Y= 1Y
+.if ${V.0x} != "0x" || ${V.1Y} != "1Y"
+. error
+.endif
+
+# The string "ASDZguv", when used as a prefix of a variable name, keeps the
+# hash code unchanged, its own hash code is 0.
+ASDZguvV.0x= 0x
+ASDZguvV.1Y= 1Y
+.if ${ASDZguvV.0x} != "0x"
+. error
+.elif ${ASDZguvV.1Y} != "1Y"
+. error
+.endif
+
+# Ensure that variables with the same hash code whose name is a prefix of the
+# other can be accessed. In this case, the shorter variable name is defined
+# first to make it appear later in the bucket of the hash table.
+ASDZguv= once
+ASDZguvASDZguv= twice
+.if ${ASDZguv} != "once"
+. error
+.elif ${ASDZguvASDZguv} != "twice"
+. error
+.endif
+
+# Ensure that variables with the same hash code whose name is a prefix of the
+# other can be accessed. In this case, the longer variable name is defined
+# first to make it appear later in the bucket of the hash table.
+ASDZguvASDZguv.param= twice
+ASDZguv.param= once
+.if ${ASDZguv.param} != "once"
+. error
+.elif ${ASDZguvASDZguv.param} != "twice"
+. error
+.endif
+
all:
