GH-251 (revert): remove coercion-to-signed-integer for |x| expressions

For `|x|`, where `x` is an expression with an integral result, an
implicit coercion of that result into signed `int` type no longer takes
place.

This was actually the behavior before Zeek 3.0 as well, but the attempt
to prevent mistakes that easily result from integer literals in Zeek
being unsigned like `|5 - 9|` causing an overflow/wraparound and
yielding a very large number is not generally consistent since overflows
are still generally able to happen in other ways and also in other
contexts besides just absolute-values.  So the preference was to revert
to a behavior that favors consistency.  For reference, see
https://github.com/zeek/zeek/pull/251#issuecomment-713956976

NEWS

@@ -98,6 +98,17 @@ Changed Functionality
   not pre-configured to listen for incoming connections from other cluster
   nodes.
 
+- The ``|x|`` operator, where ``x`` is an expression with an integral result,
+  no longer performs an implicit coercion of that result into a signed
+  ``int`` type.  This was actually the behavior before Zeek 3.0 as well, but
+  the attempt to prevent mistakes that easily result from integer literals in
+  Zeek being unsigned like ``|5 - 9|`` causing an overflow/wraparound and
+  yielding a very large number is not generally consistent since overflows
+  are still generally able to happen in other ways and also in other contexts
+  besides just the absolute-value operator.  So the preference was to revert
+  to a behavior that favors consistency.  For reference, see
+  https://github.com/zeek/zeek/pull/251#issuecomment-713956976
+
 Removed Functionality
 ---------------------
 

doc

@@ -1 +1 @@
-Subproject commit c5c73eaf52d481cee6ff180f1aa6edb75eb11e9e
+Subproject commit 36c1716769917deed461b4cc80dfb07546d4ace3

src/parse.y

@@ -767,10 +767,6 @@ expr:
 			{
 			zeek::detail::set_location(@1, @3);
 			zeek::detail::ExprPtr e{zeek::AdoptRef{}, $2};
-
-			if ( zeek::IsIntegral(e->GetType()->Tag()) )
-				e = zeek::make_intrusive<zeek::detail::ArithCoerceExpr>(std::move(e), zeek::TYPE_INT);
-
 			$$ = new zeek::detail::SizeExpr(std::move(e));
 			}
 

testing/btest/Baseline/language.sizeof/output

@@ -1,8 +1,10 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
 IPv4 Address 1.2.3.4: 32
 IPv6 Address ::1: 128
 Boolean T: 1
 Count 10: 10
-Expr: 4
+Expr: 18446744073709551612
+Signed Expr: 4
 Double -1.23: 1.230000
 Enum ENUM3: 2
 File 21.000000

testing/btest/language/sizeof.zeek

@@ -64,9 +64,14 @@ print fmt("Boolean %s: %d", b, |b|);
 # Size of count: identity.
 print fmt("Count %s: %d", c, |c|);
 
-# Size of integral arithmetic expression should coerce to int before absolute
-# value operation to help prevent common unsigned int overflow situations.
+# Integer literals that lack a "+" or "-" modifier are of the unsigned "count"
+# type, so this wraps to a very large number.  It may be more intuitive if it
+# were to coerce to a signed integer, but it can also be more favorable to
+# simply have consistent behavior across arbitrary arithmetic expressions even
+# if that may result in occassional, unintended overflow/wrapping.
 print fmt("Expr: %d", |5 - 9|);
+# Same arithmetic on signed integers is likely what's originally intended.
+print fmt("Signed Expr: %d", |+5 - +9|);
 
 # Size of double: returns absolute value.
 print fmt("Double %s: %f", d, |d|);