From 2a0923c400fe5df140e1c5aad8dc59f4733e8598 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 29 May 2024 17:07:19 +0100
Subject: make: allow :::= macro assignment on command line

GNU make and bmake have different implementations for := macro
assignment.  In POSIX 202X these are supported by the forms ::=
and :::= respectively.  Only the former was supported on the
pdpmake command line.

Add the required support in process_macros() and update the usage
message.

Adds 48-64 bytes.
---
 miscutils/make.c     | 44 ++++++++++++++++++++++++++++----------------
 testsuite/make.tests | 24 ++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/miscutils/make.c b/miscutils/make.c
index a4fecd640..8d5664500 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -51,10 +51,10 @@
 
 //usage:#define make_trivial_usage
 //usage:	IF_FEATURE_MAKE_POSIX(
-//usage:       "[--posix] [-C DIR] [-f FILE] [-j NUM] [-x PRAG] [-eiknpqrsSt] [MACRO[::]=VAL]... [TARGET]..."
+//usage:       "[--posix] [-C DIR] [-f FILE] [-j NUM] [-x PRAG] [-eiknpqrsSt] [MACRO[::[:]]=VAL]... [TARGET]..."
 //usage:	)
 //usage:	IF_NOT_FEATURE_MAKE_POSIX(
-//usage:       "[-C DIR] [-f FILE] [-j NUM] [-eiknpqrsSt] [MACRO[::]=VAL]... [TARGET]..."
+//usage:       "[-C DIR] [-f FILE] [-j NUM] [-eiknpqrsSt] [MACRO[::[:]]=VAL]... [TARGET]..."
 //usage:	)
 //usage:#define make_full_usage "\n\n"
 //usage:       "Maintain files based on their dependencies\n"
@@ -2837,12 +2837,14 @@ expand_makeflags(void)
 static char **
 process_macros(char **argv, int level)
 {
-	char *p;
+	char *equal;
 
 	for (; *argv; argv++) {
+		char *colon = NULL;
 		int idx, immediate = 0;
+		int except_dollar = FALSE;
 
-		if (!(p = strchr(*argv, '='))) {
+		if (!(equal = strchr(*argv, '='))) {
 			// Skip targets on the command line
 			if (!posix && level == 1)
 				continue;
@@ -2851,13 +2853,23 @@ process_macros(char **argv, int level)
 				break;
 		}
 
-		if (p - 2 > *argv && p[-1] == ':' && p[-2] == ':') {
+		if (equal - 2 > *argv && equal[-1] == ':' && equal[-2] == ':') {
 			if (POSIX_2017)
 				error("invalid macro assignment");
-			immediate = M_IMMEDIATE;
-			p[-2] = '\0';
+			if (equal - 3 > *argv  && equal[-3] == ':') {
+				// BSD-style ':='.  Expand RHS, but not '$$',
+				// resulting macro is delayed expansion.
+				colon = equal - 3;
+				except_dollar = TRUE;
+			} else {
+				// GNU-style ':='. Expand RHS, including '$$',
+				// resulting macro is immediate expansion.
+				colon = equal - 2;
+				immediate = M_IMMEDIATE;
+			}
+			*colon = '\0';
 		} else
-			*p = '\0';
+			*equal = '\0';
 
 		/* We want to process _most_ macro assignments.
 		 * There are exceptions for particular values from the
@@ -2866,18 +2878,18 @@ process_macros(char **argv, int level)
 		if (!(level == 3 &&
 				(idx == MAKEFLAGS || idx == SHELL ||
 					(idx == CURDIR && !useenv && !POSIX_2017)))) {
-			if (immediate) {
-				char *exp = expand_macros(p + 1, FALSE);
+			if (colon) {
+				char *exp = expand_macros(equal + 1, except_dollar);
 				setmacro(*argv, exp, level | immediate);
 				free(exp);
-			} else {
-				setmacro(*argv, p + 1, level);
-			}
+			} else
+				setmacro(*argv, equal + 1, level);
 		}
 
-		*p = '=';
-		if (immediate)
-			p[-2] = ':';
+		if (colon)
+			*colon = ':';
+		else
+			*equal = '=';
 	}
 	return argv;
 }
diff --git a/testsuite/make.tests b/testsuite/make.tests
index bac673178..0397ab4de 100755
--- a/testsuite/make.tests
+++ b/testsuite/make.tests
@@ -176,6 +176,30 @@ target:
 	@echo $(reset)
 '
 
+# Since GNU make and bmake interpret := macro assignments differently,
+# POSIX has ::= for the GNU variant and :::= for BSD.
+testing "make different styles of := macro assignment" \
+	"make -f -" \
+	'65 a a $A\n' "" '
+A = a
+GNU ::= $A
+BSD1 :::= $A
+BSD2 :::= $$A
+A = 65
+
+target:
+	@echo '\''$(A) $(GNU) $(BSD1) $(BSD2)'\''
+'
+
+# Similar to the above but for macro assignments on the command line.
+# POSIX has ::= for the GNU variant and :::= for BSD.
+testing "make := macro assignment on command line" \
+	"make -f - A=a 'GNU::=\$A' 'BSD1:::=\$A' 'BSD2:::=\$\$A' A=65" \
+	'65 a a $A\n' "" '
+target:
+	@echo '\''$(A) $(GNU) $(BSD1) $(BSD2)'\''
+'
+
 # basic pattern macro expansion
 testing "make basic pattern macro expansion" \
 	"make -f -" \
-- 
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