From cd94023239ea8608bf0d125f10ab994b201e690b Mon Sep 17 00:00:00 2001
From: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Date: Fri, 27 Dec 2024 01:24:56 +0800
Subject: [PATCH] Add support for suffixes with multiple dots

Dot-searching method in suffix() is changed from finding the last
dot (strrchr) to the first (strchr), so that the suffix of name
"foo.c.depends" is parsed as ".c.depends" instead of ".depends".

The inference rule matching logic in target_type() is extended to
an iterative loop to cover possible prefix-suffix combinations of
multi-dot sequences. A rule ".x.y.z:" is matched as prefix-suffix
pair ".x|.y.z", then ".x.y|.z", and then single-suffix ".x.y.z".
---
 input.c              | 29 ++++++++++++++++-------------
 rules.c              |  2 +-
 testsuite/make.tests | 13 +++++++++++++
 3 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/input.c b/input.c
index 7f454f9..a00bf7e 100644
--- a/input.c
+++ b/input.c
@@ -723,20 +723,23 @@ target_type(char *s)
 			return s_type[ret];
 
 	// Check for an inference rule
-	ret = T_NORMAL;
-	sfx = suffix(s);
-	if (is_suffix(sfx)) {
-		if (s == sfx) {	// Single suffix rule
-			ret = T_INFERENCE | T_NOPREREQ | T_COMMAND;
-		} else {
-			// Suffix is valid, check that prefix is too
-			*sfx = '\0';
-			if (is_suffix(s))
-				ret = T_INFERENCE | T_NOPREREQ | T_COMMAND;
-			*sfx = '.';
-		}
+	for (sfx = s; (sfx = strchr(sfx + 1, '.'));) {
+		if (!is_suffix(sfx))
+			continue;
+
+		// Suffix is valid, check that prefix is too
+		*sfx = '\0';
+		ret = is_suffix(s);
+		*sfx = '.';
+
+		if (ret)
+			return T_INFERENCE | T_NOPREREQ | T_COMMAND;
 	}
-	return ret;
+
+	if (is_suffix(s)) // Single suffix rule
+		return T_INFERENCE | T_NOPREREQ | T_COMMAND;
+
+	return T_NORMAL;
 }
 
 #if ENABLE_FEATURE_MAKE_EXTENSIONS
diff --git a/rules.c b/rules.c
index d92cc84..feab556 100644
--- a/rules.c
+++ b/rules.c
@@ -10,7 +10,7 @@
 char *
 suffix(const char *name)
 {
-	char *p = strrchr(name, '.');
+	char *p = strchr(name, '.');
 	return p ? p : (char *)name + strlen(name);
 }
 
diff --git a/testsuite/make.tests b/testsuite/make.tests
index 881322e..32a46cd 100755
--- a/testsuite/make.tests
+++ b/testsuite/make.tests
@@ -100,6 +100,19 @@ x.p:
 '
 cd .. || exit 1; rm -rf make.tempdir 2>/dev/null
 
+# Suffixes with multiple dots are supported
+mkdir make.tempdir && cd make.tempdir || exit 1
+testing "Support multi-dot suffixes" \
+	"make -f -" "touch x.c.c\ncat x.c.c >x.o.o\n" "" '
+.SUFFIXES: .c.c .o.o
+x.o.o:
+x.c.c:
+	touch $@
+.c.c.o.o:
+	cat $< >$@
+'
+cd .. || exit 1; rm -rf make.tempdir 2>/dev/null
+
 # Austin Group defect report 875 clarifies certain aspects of the
 # behaviour of inference rules.  Study of this resulted in a number
 # of changes to pdpmake, though this test passed anyway.