[src/trunk]: src/usr.bin/make make: only evaluate the ':_' modifier if the ex...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a54bbd234079
branches:  trunk
changeset: 1019574:a54bbd234079
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Mar 14 16:43:30 2021 +0000

description:
make: only evaluate the ':_' modifier if the expression is needed

See var-eval-short.mk:46 for the test demonstrating this change.
Previously, the expression ${:Uword:_=VAR} was evaluated including all
its side effects even though it was in an irrelevant branch of the
condition.

diffstat:

 usr.bin/make/unit-tests/var-eval-short.exp |   1 -
 usr.bin/make/var.c                         |  26 ++++++++++++++++----------
 2 files changed, 16 insertions(+), 11 deletions(-)

diffs (70 lines):

diff -r 55649470418b -r a54bbd234079 usr.bin/make/unit-tests/var-eval-short.exp
--- a/usr.bin/make/unit-tests/var-eval-short.exp        Sun Mar 14 16:03:04 2021 +0000
+++ b/usr.bin/make/unit-tests/var-eval-short.exp        Sun Mar 14 16:43:30 2021 +0000
@@ -1,7 +1,6 @@
 unexpected
 make: Bad modifier ":[${FAIL" for variable ""
 make: "var-eval-short.mk" line 43: Malformed conditional (0 && ${:Uword:[${FAIL}]})
-make: "var-eval-short.mk" line 48: Missing argument for ".error"
 make: "var-eval-short.mk" line 63: Invalid time value: ${FAIL}}
 make: "var-eval-short.mk" line 63: Malformed conditional (0 && ${:Uword:gmtime=${FAIL}})
 make: "var-eval-short.mk" line 77: Invalid time value: ${FAIL}}
diff -r 55649470418b -r a54bbd234079 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sun Mar 14 16:03:04 2021 +0000
+++ b/usr.bin/make/var.c        Sun Mar 14 16:43:30 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.865 2021/03/14 16:03:04 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.866 2021/03/14 16:43:30 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -140,7 +140,7 @@
 #include "metachar.h"
 
 /*     "@(#)var.c      8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: var.c,v 1.865 2021/03/14 16:03:04 rillig Exp $");
+MAKE_RCSID("$NetBSD: var.c,v 1.866 2021/03/14 16:43:30 rillig Exp $");
 
 typedef enum VarFlags {
        VFL_NONE        = 0,
@@ -3418,6 +3418,7 @@
 {
        Expr *expr = st->expr;
        const char *mod = *pp;
+
        if (!ModMatchEq(mod, "_", st))
                return AMR_UNKNOWN;
 
@@ -3428,19 +3429,24 @@
                 * unnecessary, undocumented inconsistency in make.
                 */
                size_t n = strcspn(mod + 2, ":)}");
-               char *name = bmake_strldup(mod + 2, n);
                *pp = mod + 2 + n;
 
-               /*
-                * FIXME: do not expand the variable name here; it would only
-                *  work for single-character variable names anyway.
-                */
-               Var_SetExpand(expr->scope, name, expr->value.str);
-               free(name);
+               if (expr->eflags & VARE_WANTRES) {
+                       char *name = bmake_strldup(mod + 2, n);
+
+                       /*
+                        * FIXME: do not expand the variable name here; it
+                        * would only work for single-character variable names
+                        * anyway.
+                        */
+                       Var_SetExpand(expr->scope, name, expr->value.str);
+                       free(name);
+               }
        } else {
                *pp = mod + 1;
 
-               Var_Set(expr->scope, "_", expr->value.str);
+               if (expr->eflags & VARE_WANTRES)
+                       Var_Set(expr->scope, "_", expr->value.str);
        }
        return AMR_OK;
 }