From 5f56a0388271d2de6cf31af1041bdcb3d11029fc Mon Sep 17 00:00:00 2001
From: Denys Vlasenko
Date: Thu, 15 Jun 2023 10:07:12 +0200
Subject: shell/math: fix parsing of ?: and explain why it's parsed that way

This fixes arith-precedence1.tests.

This breaks arith-ternary2.tests again (we now evaluate variables
on not-taken branches). We need a better logic here anyway:
not only bare variables should not evaluate when not-taken:
	1 ? eval_me : do_not_eval
but any (arbitrarily complex) expressions shouldn't
evaluate as well!
	1 ? var_is_set=1 : ((var_is_not_set=2,var2*=4))

function                                             old     new   delta
evaluate_string                                     1097    1148     +51

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
 shell/hush_test/hush-arith/arith-precedence1.right     |  4 ++++
 shell/hush_test/hush-arith/arith-precedence1.tests     | 15 +++++++++++++++
 shell/hush_test/hush-arith/arith-ternary2.right        |  3 ---
 shell/hush_test/hush-arith/arith-ternary2.tests        |  7 -------
 shell/hush_test/hush-arith/arith-ternary_nested1.right |  1 +
 shell/hush_test/hush-arith/arith-ternary_nested1.tests |  2 ++
 shell/hush_test/hush-arith/arith.right                 |  2 +-
 7 files changed, 23 insertions(+), 11 deletions(-)
 create mode 100644 shell/hush_test/hush-arith/arith-precedence1.right
 create mode 100755 shell/hush_test/hush-arith/arith-precedence1.tests
 delete mode 100644 shell/hush_test/hush-arith/arith-ternary2.right
 delete mode 100755 shell/hush_test/hush-arith/arith-ternary2.tests
 create mode 100644 shell/hush_test/hush-arith/arith-ternary_nested1.right
 create mode 100755 shell/hush_test/hush-arith/arith-ternary_nested1.tests

(limited to 'shell/hush_test/hush-arith')

diff --git a/shell/hush_test/hush-arith/arith-precedence1.right b/shell/hush_test/hush-arith/arith-precedence1.right
new file mode 100644
index 0000000..3f9320a
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith-precedence1.right
@@ -0,0 +1,4 @@
+4:4
+4:4
+4:4
+4:4
diff --git a/shell/hush_test/hush-arith/arith-precedence1.tests b/shell/hush_test/hush-arith/arith-precedence1.tests
new file mode 100755
index 0000000..bfef052
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith-precedence1.tests
@@ -0,0 +1,15 @@
+exec 2>&1
+# bash documentation says that precedence order is:
+#  ...
+#  expr ? expr1 : expr2
+#  = *= /= %= += -= <<= >>= &= ^= |=
+#  exprA , exprB
+# but in practice, the rules for expr1 and expr2 are different:
+# assignments and commas in expr1 have higher precedence than :?,
+# but in expr2 they haven't:
+# "v ? 1,2 : 3,4" is parsed as "(v ? (1,2) : 3),4"
+# "v ? a=2 : b=4" is parsed as "(v ? (a=1) : b)=4" (thus, this is a syntax error)
+echo 4:$((0 ? 1,2 : 3,4))
+echo 4:$((1 ? 1,2 : 3,4))
+echo 4:"$((0 ? 1,2 : 3,4))"
+echo 4:"$((1 ? 1,2 : 3,4))"
diff --git a/shell/hush_test/hush-arith/arith-ternary2.right b/shell/hush_test/hush-arith/arith-ternary2.right
deleted file mode 100644
index a549b1b..0000000
--- a/shell/hush_test/hush-arith/arith-ternary2.right
+++ /dev/null
@@ -1,3 +0,0 @@
-6:6
-a=b=+err+
-b=6
diff --git a/shell/hush_test/hush-arith/arith-ternary2.tests b/shell/hush_test/hush-arith/arith-ternary2.tests
deleted file mode 100755
index cb31639..0000000
--- a/shell/hush_test/hush-arith/arith-ternary2.tests
+++ /dev/null
@@ -1,7 +0,0 @@
-exec 2>&1
-a='b=+err+'
-b=5
-# The not-taken branch should not parse variables
-echo 6:$((0 ? a : ++b))
-echo "a=$a"
-echo "b=$b"
diff --git a/shell/hush_test/hush-arith/arith-ternary_nested1.right b/shell/hush_test/hush-arith/arith-ternary_nested1.right
new file mode 100644
index 0000000..d803196
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith-ternary_nested1.right
@@ -0,0 +1 @@
+3:3
diff --git a/shell/hush_test/hush-arith/arith-ternary_nested1.tests b/shell/hush_test/hush-arith/arith-ternary_nested1.tests
new file mode 100755
index 0000000..469584b
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith-ternary_nested1.tests
@@ -0,0 +1,2 @@
+exec 2>&1
+echo 3:$((1?(2?(3):4):5))
diff --git a/shell/hush_test/hush-arith/arith.right b/shell/hush_test/hush-arith/arith.right
index a861229..df8154f 100644
--- a/shell/hush_test/hush-arith/arith.right
+++ b/shell/hush_test/hush-arith/arith.right
@@ -94,7 +94,7 @@ ghi
 hush: arithmetic syntax error
 16 16
 hush: arithmetic syntax error
-hush: malformed ?: operator
+hush: arithmetic syntax error
 hush: arithmetic syntax error
 9 9
 hush: arithmetic syntax error
-- 
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