fix: do not remove existing temp files in case of dryrun

snakemake/dag.py

@@ -642,8 +642,11 @@ def unneeded_files():
                 yield from filterfalse(partial(needed, job), tempfiles)
 
         for f in unneeded_files():
-            logger.info("Removing temporary output file {}.".format(f))
-            f.remove(remove_non_empty_dir=True)
+            if self.dryrun:
+                logger.info(f"Would remove temporary output {f}")
+            else:
+                logger.info("Removing temporary output {}.".format(f))
+                f.remove(remove_non_empty_dir=True)
 
     def handle_log(self, job, upload_remote=True):
         for f in job.log:

tests/test_github_issue1542/Snakefile

@@ -0,0 +1,20 @@
+# Snakefile
+rule all:
+    input:
+        "b.txt",
+
+
+rule a:
+    output:
+        temp("a.txt"),
+    shell:
+        "touch a.txt"
+
+
+rule b:
+    input:
+        "a.txt",
+    output:
+        "b.txt",
+    shell:
+        "touch b.txt"

tests/tests.py

@@ -1575,3 +1575,7 @@ def test_pipe_depend():
 @skip_on_windows  # no pipe support on windows
 def test_pipe_depend_target_file():
     run(dpath("test_pipe_depend"), targets=["test.txt"], shouldfail=True)
+
+
+def test_github_issue1542():
+    run(dpath("test_github_issue1542"), dryrun=True)