make: fix single-suffix inference rule regression

Commit 85bbce87d (make: support GNU/BSD suffixes and inference
rules) added code to handle inference rules with arbitrary
suffixes.  Unfortunately it failed to check for a single-suffix
rule in the case where no known suffix was found.  Add the
necessary code and a test which would have caught the problem.

Adds 48 bytes.

(pdpmake GitHub issue 72)

2 files changed, 24 insertions, 3 deletions

diff --git a/miscutils/make.c b/miscutils/make.c
index ceac1d91d..39c0081ab 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -1100,22 +1100,34 @@ dyndep(struct name *np, struct rule *infrule, const char **ptsuff)
         // targets of the form lib.a(member.o).
         if (!posix && member == NULL) {
                 struct name *xp = newname(".SUFFIXES");
+                int found_suffix = FALSE;
+
                 for (struct rule *rp = xp->n_rule; rp; rp = rp->r_next) {
                         for (struct depend *dp = rp->r_dep; dp; dp = dp->d_next) {
                                 tsuff = dp->d_name->n_name;
                                 base = has_suffix(name, tsuff);
                                 if (base) {
+                                        found_suffix = TRUE;
                                         pp = dyndep0(base, tsuff, infrule);
                                         free(base);
                                         if (pp) {
-                                                if (ptsuff)
-                                                        *ptsuff = tsuff;
                                                 goto done;
                                         }
                                 }
                         }
                 }
 
+                if (!found_suffix) {
+                        // The name didn't have a known suffix. Try single-suffix rule.
+                        tsuff = "";
+                        pp = dyndep0(name, tsuff, infrule);
+                        if (pp) {
+ done:
+                                if (ptsuff) {
+                                        *ptsuff = tsuff;
+                                }
+                        }
+                }
         } else {
                 tsuff = xstrdup(suffix(name));
                 base = member ? member : name;
@@ -1124,7 +1136,6 @@ dyndep(struct name *np, struct rule *infrule, const char **ptsuff)
                 pp = dyndep0(base, tsuff, infrule);
                 free((void *)tsuff);
         }
- done:
         free(name);
 
         return pp;
diff --git a/testsuite/make.tests b/testsuite/make.tests
index e3103c514..fabdbe45c 100755
--- a/testsuite/make.tests
+++ b/testsuite/make.tests
@@ -86,6 +86,16 @@ test.k:
 '
 cd .. || exit 1; rm -rf make.tempdir 2>/dev/null
 
+# Check that single-suffix inference rules work.
+mkdir make.tempdir && cd make.tempdir || exit 1
+touch test.sh
+testing "make single-suffix inference rule works" \
+        "make -f - -s; echo $?" \
+        "0\n" "" '
+test:
+'
+cd .. || exit 1; rm -rf make.tempdir 2>/dev/null
+
 # There was a bug where the failure of a build command didn't result
 # in make returning a non-zero exit status.
 testing "make return error if command fails" \