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make.1: clarify interpretation of conditionals 

String literals in quotes are never interpreted as numbers.

The operators '<', '<=', '>', '>=' are only allowed in numeric
comparisons.

Avoid the term 'C relational operators' since in C, the relational
operators exclude '==' and '!=', which are called equality operators
instead.
This commit is contained in:
rillig 2022-09-05 17:13:36 +00:00
parent ef7e7fa51d
commit 33a45076d3
1 changed files with 23 additions and 18 deletions
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41
usr.bin/make/make.1
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@ -1,4 +1,4 @@
.\" $NetBSD: make.1,v 1.332 2022/09/03 00:50:07 rillig Exp $
.\" $NetBSD: make.1,v 1.333 2022/09/05 17:13:36 rillig Exp $
.\"
.\" Copyright (c) 1990, 1993
.\" The Regents of the University of California. All rights reserved.
@ -2011,23 +2011,28 @@ has been defined and has commands associated with it.
.Pp
.Ar Expression
may also be an arithmetic or string comparison.
Variable expansion is
performed on both sides of the comparison, after which the numerical
values are compared.
A value is interpreted as hexadecimal if it is
preceded by 0x, otherwise it is decimal; octal numbers are not supported.
The standard C relational operators are all supported.
If after
variable expansion, either the left or right hand side of a
.Sq Ic ==
or
.Sq Ic "!="
operator is not a numerical value, then
string comparison is performed between the expanded
variables.
If no relational operator is given, it is assumed that the expanded
variable is being compared against 0, or an empty string in the case
of a string comparison.
Variable expansion is performed on both sides of the comparison.
If both sides are numeric and neither is enclosed in quotes,
the comparison is done numerically, otherwise lexicographically.
A string is interpreted as hexadecimal integer if it is preceded by
.Li 0x ,
otherwise it is a decimal floating-point number;
octal numbers are not supported.
.Pp
All comparisons may use the operators
.Sq Ic \&==
and
.Sq Ic \&!= .
Numeric comparisons may also use the operators
.Sq Ic \&< ,
.Sq Ic \&<= ,
.Sq Ic \&>
and
.Sq Ic \&>= .
.Pp
If the comparison has neither a comparison operator nor a right side,
the expression evaluates to true if it is nonempty
and its numeric value (if any) is not zero.
.Pp
When
.Nm