From: Marc Espie <marc.espie.openbsd@gmail.com>
Subject: patch: tweak make "magic variables" handling
To: tech@openbsd.org
Date: Tue, 25 Nov 2025 12:03:33 +0100

The idea is that it's shorter to special-case ${@D} and the likes
(two characters variables ending in D or F) instead of having a weird
idx encoding.

Cons: 
- this yields an extra "ext" parameter to classify_var
Pros:
- the weird index encoding vanishes
- no need for special treatment if we add more similar variables.
- drastically reduces the size of the switch (and the modulo shrinks from
82 to 36)
- code will recognize constructs like ${?D} and ${?F}, which puts us in
line with FreeBSD and NetBSD bmake, and also with gnu make.

Index: Makefile
===================================================================
RCS file: /build/data/openbsd/cvs/src/usr.bin/make/Makefile,v
diff -u -p -r1.65 Makefile
--- Makefile	4 Sep 2023 11:35:11 -0000	1.65
+++ Makefile	22 Nov 2025 09:42:30 -0000
@@ -27,7 +27,7 @@ CLEANFILES+=generate generate.o regress.
 CLEANFILES+= varhashconsts.h condhashconsts.h nodehashconsts.h
 
 # may need tweaking if you add variable synonyms or change the hash function
-MAGICVARSLOTS=82
+MAGICVARSLOTS=36
 MAGICCONDSLOTS=65
 
 varhashconsts.h: generate
Index: generate.c
===================================================================
RCS file: /build/data/openbsd/cvs/src/usr.bin/make/generate.c,v
diff -u -p -r1.18 generate.c
--- generate.c	14 Oct 2016 09:27:21 -0000	1.18
+++ generate.c	22 Nov 2025 14:59:44 -0000
@@ -53,16 +53,6 @@ char *table_var[] = {
 	M(LONGPREFIX),
 	M(LONGARCHIVE),
 	M(LONGMEMBER),
-	M(FTARGET),
-	M(DTARGET),
-	M(FPREFIX),
-	M(DPREFIX),
-	M(FARCHIVE),
-	M(DARCHIVE),
-	M(FMEMBER),
-	M(DMEMBER),
-	M(FIMPSRC),
-	M(DIMPSRC),
 	NULL
 };
 
Index: make.1
===================================================================
RCS file: /build/data/openbsd/cvs/src/usr.bin/make/make.1,v
diff -u -p -r1.141 make.1
--- make.1	10 Aug 2023 10:56:34 -0000	1.141
+++ make.1	25 Nov 2025 11:02:57 -0000
@@ -639,19 +639,24 @@ The file prefix of the file, containing 
 no suffix or preceding directory components.
 .El
 .Pp
-The six variables
-.Sq Va "@F" ,
-.Sq Va "@D" ,
-.Sq Va "<F" ,
-.Sq Va "<D" ,
-.Sq Va "*F" ,
+Those variables
+.Po
 and
-.Sq Va "*D"
-yield the
-.Qq filename
+.Va \&>
+.Pc
+may be suffixed with a
+.Sq D
+or a
+.Sq F ,
+to yield the filename or directory part of the corresponding variables, e.g.,
+.Sq ${ Ns Va @F Ns }
+is equivalent
+to
+.Sq ${@:T}
 and
-.Qq directory
-parts of the corresponding macros.
+.Sq ${ Ns Va @D Ns }
+is equivalent to
+.Sq ${@:H} .
 .Pp
 For maximum compatibility,
 .Sq Va \&<
Index: var.c
===================================================================
RCS file: /build/data/openbsd/cvs/src/usr.bin/make/var.c,v
diff -u -p -r1.107 var.c
--- var.c	18 Jun 2024 02:11:04 -0000	1.107
+++ var.c	22 Nov 2025 15:00:25 -0000
@@ -152,16 +152,6 @@ static char *varnames[] = {
 	IMPSRC,
 	OODATE,
 	ALLSRC,
-	FTARGET,
-	DTARGET,
-	FPREFIX,
-	DPREFIX,
-	FARCHIVE,
-	DARCHIVE,
-	FMEMBER,
-	DMEMBER,
-	FIMPSRC,
-	DIMPSRC
 };
 
 static bool xtlist[] = {
@@ -173,16 +163,6 @@ static bool xtlist[] = {
 	true,	/* $< */
 	false,	/* $? */
 	false,	/* $> */
-	true,	/* ${@F} */
-	true,	/* ${@D} */
-	false,	/* ${*F} */
-	false,	/* ${*D} */
-	false,	/* ${!F} */
-	false,	/* ${!D} */
-	true,	/* ${%F} */
-	true,	/* ${%D} */
-	true,	/* ${<F} */
-	true,	/* ${<D} */
 };
 
 /* so that we can access tlist[-1] */
@@ -191,23 +171,8 @@ static bool *tlist = xtlist+1;
 /* hashed names of dynamic variables */
 #include    "varhashconsts.h"
 
-/* extended indices for System V stuff */
-#define FTARGET_INDEX	7
-#define DTARGET_INDEX	8
-#define FPREFIX_INDEX	9
-#define DPREFIX_INDEX	10
-#define FARCHIVE_INDEX	11
-#define DARCHIVE_INDEX	12
-#define FMEMBER_INDEX	13
-#define DMEMBER_INDEX	14
-#define FIMPSRC_INDEX	15
-#define DIMPSRC_INDEX	16
-
 #define GLOBAL_INDEX	-1
 
-#define EXTENDED2SIMPLE(i)	(((i)-LOCAL_SIZE)/2)
-#define IS_EXTENDED_F(i)	((i)%2 == 1)
-
 
 static struct ohash global_variables;
 
@@ -242,7 +207,7 @@ static struct ohash_info var_info = {
 	hash_calloc, hash_free, element_alloc
 };
 
-static int classify_var(const char *, const char **, uint32_t *);
+static int classify_var(const char *, const char **, uint32_t *, char *);
 static Var *find_global_var(const char *, const char *, uint32_t);
 static Var *find_global_var_without_env(const char *, const char *, uint32_t);
 static void fill_from_env(Var *);
@@ -269,7 +234,7 @@ typedef const char * (*find_t)(const cha
 static find_t find_pos(int);
 static void push_used(Var *);
 static void pop_used(Var *);
-static char *get_expanded_value(const char *, const char *, int, uint32_t,
+static char *get_expanded_value(const char *, const char *, int, uint32_t, char,
     SymTable *, bool, bool *);
 static bool parse_base_variable_name(const char **, struct Name *, SymTable *);
 
@@ -279,14 +244,25 @@ static bool parse_base_variable_name(con
  * GLOBAL_INDEX if name is not dynamic. Set up *pk for further use.
  */
 static int
-classify_var(const char *name, const char **enamePtr, uint32_t *pk)
+classify_var(const char *name, const char **enamePtr, uint32_t *pk, char *ext)
 {
 	size_t len;
+	uint32_t k;
+	*ext = 0;
+
 
 	*pk = ohash_interval(name, enamePtr);
 	len = *enamePtr - name;
+
+	/* special treatment: @D/@F and the likes */
+	k = *pk;
+	if (len == 2 && (name[1] == 'D' || name[1] == 'F')) {
+		*ext = name[1];
+		len--;
+		k = name[0];
+	}
 	    /* substitute short version for long local name */
-	switch (*pk % MAGICSLOTS1) {	/* MAGICSLOTS should be the    */
+	switch (k % MAGICSLOTS1) {	/* MAGICSLOTS should be the    */
 	case K_LONGALLSRC % MAGICSLOTS1:/* smallest constant yielding  */
 					/* distinct case values	   */
 		if (*pk == K_LONGALLSRC && len == strlen(LONGALLSRC) &&
@@ -351,48 +327,6 @@ classify_var(const char *name, const cha
 		if (name[0] == MEMBER[0] && len == 1)
 			return MEMBER_INDEX;
 		break;
-	case K_FTARGET % MAGICSLOTS1:
-		if (name[0] == FTARGET[0] && name[1] == FTARGET[1] && len == 2)
-			return FTARGET_INDEX;
-		break;
-	case K_DTARGET % MAGICSLOTS1:
-		if (name[0] == DTARGET[0] && name[1] == DTARGET[1] && len == 2)
-			return DTARGET_INDEX;
-		break;
-	case K_FPREFIX % MAGICSLOTS1:
-		if (name[0] == FPREFIX[0] && name[1] == FPREFIX[1] && len == 2)
-			return FPREFIX_INDEX;
-		break;
-	case K_DPREFIX % MAGICSLOTS1:
-		if (name[0] == DPREFIX[0] && name[1] == DPREFIX[1] && len == 2)
-			return DPREFIX_INDEX;
-		break;
-	case K_FARCHIVE % MAGICSLOTS1:
-		if (name[0] == FARCHIVE[0] && name[1] == FARCHIVE[1] &&
-		    len == 2)
-			return FARCHIVE_INDEX;
-		break;
-	case K_DARCHIVE % MAGICSLOTS1:
-		if (name[0] == DARCHIVE[0] && name[1] == DARCHIVE[1] &&
-		    len == 2)
-			return DARCHIVE_INDEX;
-		break;
-	case K_FMEMBER % MAGICSLOTS1:
-		if (name[0] == FMEMBER[0] && name[1] == FMEMBER[1] && len == 2)
-			return FMEMBER_INDEX;
-		break;
-	case K_DMEMBER % MAGICSLOTS1:
-		if (name[0] == DMEMBER[0] && name[1] == DMEMBER[1] && len == 2)
-			return DMEMBER_INDEX;
-		break;
-	case K_FIMPSRC % MAGICSLOTS1:
-		if (name[0] == FIMPSRC[0] && name[1] == FIMPSRC[1] && len == 2)
-			return FIMPSRC_INDEX;
-		break;
-	case K_DIMPSRC % MAGICSLOTS1:
-		if (name[0] == DIMPSRC[0] && name[1] == DIMPSRC[1] && len == 2)
-			return DIMPSRC_INDEX;
-		break;
 	default:
 		break;
 	}
@@ -569,7 +503,8 @@ Var_Mark(const char *name, const char *e
 	Var   *v;
 	uint32_t	k;
 	int		idx;
-	idx = classify_var(name, &ename, &k);
+	char		ext;
+	idx = classify_var(name, &ename, &k, &ext);
 
 	if (idx != GLOBAL_INDEX) {
 		Parse_Error(PARSE_FATAL,
@@ -623,8 +558,9 @@ Var_Deletei(const char *name, const char
 	uint32_t k;
 	unsigned int slot;
 	int idx;
+	char ext;
 
-	idx = classify_var(name, &ename, &k);
+	idx = classify_var(name, &ename, &k, &ext);
 	if (idx != GLOBAL_INDEX) {
 		Parse_Error(PARSE_FATAL,
 		    "Trying to delete dynamic variable $%s", varnames[idx]);
@@ -656,8 +592,9 @@ var_set_append(const char *name, const c
 	Var *v;
 	uint32_t k;
 	int idx;
+	char ext;
 
-	idx = classify_var(name, &ename, &k);
+	idx = classify_var(name, &ename, &k, &ext);
 	if (idx != GLOBAL_INDEX) {
 		Parse_Error(PARSE_FATAL, "Trying to %s dynamic variable $%s",
 		    append ? "append to" : "set", varnames[idx]);
@@ -754,8 +691,9 @@ Var_Valuei(const char *name, const char 
 	Var *v;
 	uint32_t k;
 	int idx;
+	char ext;
 
-	idx = classify_var(name, &ename, &k);
+	idx = classify_var(name, &ename, &k, &ext);
 	if (idx != GLOBAL_INDEX) {
 		Parse_Error(PARSE_FATAL,
 		    "Trying to get value of dynamic variable $%s",
@@ -777,8 +715,9 @@ Var_Definedi(const char *name, const cha
 	Var *v;
 	uint32_t k;
 	int idx;
+	char ext;
 
-	idx = classify_var(name, &ename, &k);
+	idx = classify_var(name, &ename, &k, &ext);
 	/* We don't bother writing an error message for dynamic variables,
 	 * these will be caught when getting set later, usually.
 	 */
@@ -952,7 +891,7 @@ pop_used(Var *v)
 
 static char *
 get_expanded_value(const char *name, const char *ename, int idx, uint32_t k,
-    SymTable *ctxt, bool err, bool *freePtr)
+    char ext, SymTable *ctxt, bool err, bool *freePtr)
 {
 	char *val;
 
@@ -984,20 +923,17 @@ get_expanded_value(const char *name, con
 		}
 	} else {
 		if (ctxt != NULL) {
-			if (idx < LOCAL_SIZE)
-				val = ctxt->locals[idx];
-			else
-				val = ctxt->locals[EXTENDED2SIMPLE(idx)];
+			val = ctxt->locals[idx];
 		} else
 			val = NULL;
 		if (val == NULL)
 			return NULL;
 
-		if (idx >= LOCAL_SIZE) {
-			if (IS_EXTENDED_F(idx))
-				val = Var_GetTail(val);
-			else
-				val = Var_GetHead(val);
+		if (ext == 'F') {
+			val = Var_GetTail(val);
+			*freePtr = true;
+		} else if (ext == 'D') {
+			val = Var_GetHead(val);
 			*freePtr = true;
 		}
 	}
@@ -1012,8 +948,6 @@ bad_dynamic_variable(int idx)
 	Location origin;
 
 	Parse_FillLocation(&origin);
-	if (idx >= LOCAL_SIZE)
-		idx = EXTENDED2SIMPLE(idx);
 	switch(idx) {
 	case IMPSRC_INDEX:
 		if (origin.fname)
@@ -1050,6 +984,7 @@ Var_Parse(const char *str,	/* The string
 	uint32_t k;
 	int idx;
 	bool has_modifier;
+	char ext;
 
 	*freePtr = false;
 
@@ -1063,8 +998,9 @@ Var_Parse(const char *str,	/* The string
 
 	has_modifier = parse_base_variable_name(&tstr, &name, ctxt);
 
-	idx = classify_var(name.s, &name.e, &k);
-	val = get_expanded_value(name.s, name.e, idx, k, ctxt, err, freePtr);
+	idx = classify_var(name.s, &name.e, &k, &ext);
+	val = get_expanded_value(name.s, name.e, idx, k, ext, ctxt, err, 
+	    freePtr);
 	if (has_modifier) {
 		val = VarModifiers_Apply(val, &name, ctxt, err, freePtr,
 		    &tstr, str[1]);
@@ -1183,6 +1119,7 @@ Var_Check_for_target(const char *str)
 		int idx;
 		bool has_modifier;
 		struct Name name;
+		char ext;
 
 		/* skip over uninteresting stuff */
 		for (; *str != '\0' && *str != '$'; str++)
@@ -1198,7 +1135,7 @@ Var_Check_for_target(const char *str)
 		tstr = str;
 
 		has_modifier = parse_base_variable_name(&tstr, &name, NULL);
-		idx = classify_var(name.s, &name.e, &k);
+		idx = classify_var(name.s, &name.e, &k, &ext);
 		if (has_modifier) {
 			bool doFree = false;
 			char *val = VarModifiers_Apply(NULL, NULL, NULL, false, 
Index: var_int.h
===================================================================
RCS file: /build/data/openbsd/cvs/src/usr.bin/make/var_int.h,v
diff -u -p -r1.2 var_int.h
--- var_int.h	19 Jul 2010 19:46:44 -0000	1.2
+++ var_int.h	22 Nov 2025 15:00:54 -0000
@@ -42,16 +42,4 @@
 #define LONGARCHIVE	".ARCHIVE"
 #define LONGMEMBER	".MEMBER"
 
-/* System V   extended variables (get directory/file part) */
-#define FTARGET		"@F"
-#define DTARGET		"@D"
-#define FIMPSRC		"<F"
-#define DIMPSRC		"<D"
-#define FPREFIX		"*F"
-#define DPREFIX		"*D"
-#define FARCHIVE	"!F"
-#define DARCHIVE	"!D"
-#define FMEMBER		"%F"
-#define DMEMBER		"%D"
-
 #endif