From 5e27caa60c4ccf257c0dca64883cdf672d8d8ce4 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 15 Jan 2020 10:21:18 -0500
Subject: [PATCH 1/2] compat_compiler: add a macro to prevent coverity deadcode
 warnings.

The POSSIBLE(e) macro evaluates to the value of (e), but does so in
a way that a static analyzer will not conclude that (e) is
impossible.  We can use this when we expect our regular compilers to
eliminate deadcode, but we don't want coverity to complain about it.

Part of a fix for 32960.
---
 src/lib/cc/compat_compiler.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/lib/cc/compat_compiler.h b/src/lib/cc/compat_compiler.h
index 47782fda08..907622f942 100644
--- a/src/lib/cc/compat_compiler.h
+++ b/src/lib/cc/compat_compiler.h
@@ -227,4 +227,17 @@
 #define EAT_SEMICOLON                                   \
   struct dummy_semicolon_eater__
 
+/**
+ * Tell our static analysis tool to believe that (clang's scan-build or
+ * coverity scan) that an expression might be true.  We use this to suppress
+ * dead-code warnings.
+ **/
+#if defined(__COVERITY__) || defined(__clang_analyzer__)
+/* By calling getenv, we force the analyzer not to conclude that 'expr' is
+ * false. */
+#define POSSIBLE(expr) ((expr) || getenv("STATIC_ANALYZER_DEADCODE_DUMMY_"))
+#else
+#define POSSIBLE(expr) (expr)
+#endif
+
 #endif /* !defined(TOR_COMPAT_COMPILER_H) */

From 77246dc0d8b90e99bb411475da1911919799dae8 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 15 Jan 2020 10:30:03 -0500
Subject: [PATCH 2/2] Tell static analyzer that having ntservice functions not
 exist is ok

When we made these functions exist unconditionally (as macros on
non-windows platforms), we started to get a dead-code warning on
Coverity.  We now use a macro to tell coverity not to worry about
this particular dead-code instance.
---
 src/app/main/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/app/main/main.c b/src/app/main/main.c
index 36f85c6a40..b533406eaa 100644
--- a/src/app/main/main.c
+++ b/src/app/main/main.c
@@ -1240,7 +1240,7 @@ tor_run_main(const tor_main_configuration_t *tor_cfg)
 
   int done = 0;
   result = nt_service_parse_options(argc, argv, &done);
-  if (done)
+  if (POSSIBLE(done))
     goto done;
 
   pubsub_install();