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spec: fix binary expression grammar rule

The spec explains later in the "Operator precedence" section that *
has a higher precedence than +, but the current production rule
requires that "1 + 2 * 3" be parsed as "(1 + 2) * 3", instead of the
intended "1 + (2 * 3)".

The new production rule better matches cmd/internal/gc/go.y's grammar:

    expr:
            uexpr
    |       expr LOROR expr
    |       expr LANDAND expr
    |       ...

Fixes #10151.

Change-Id: I13c9635d6ddf1263cafe7cc63e68f3e5779e24ba
Reviewed-on: https://go-review.googlesource.com/9163
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2015-04-20 17:17:24 -07:00 committed by Robert Griesemer
parent 99475dfb59
commit abb818bc03

View File

@ -1,6 +1,6 @@
<!--{
"Title": "The Go Programming Language Specification",
"Subtitle": "Version of March 20, 2015",
"Subtitle": "Version of April 22, 2015",
"Path": "/ref/spec"
}-->
@ -3305,7 +3305,7 @@ Operators combine operands into expressions.
</p>
<pre class="ebnf">
Expression = UnaryExpr | Expression binary_op UnaryExpr .
Expression = UnaryExpr | Expression binary_op Expression .
UnaryExpr = PrimaryExpr | unary_op UnaryExpr .
binary_op = "||" | "&amp;&amp;" | rel_op | add_op | mul_op .