6 files changed, 58 insertions, 14 deletions
diff --git a/src/lib/cc/compat_compiler.h b/src/lib/cc/compat_compiler.h
index 3ef866ecce..1bb8c54a0c 100644
--- a/src/lib/cc/compat_compiler.h
+++ b/src/lib/cc/compat_compiler.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
@@ -59,8 +59,6 @@
 
 /* Temporarily enable and disable warnings. */
 #ifdef __GNUC__
-#  define PRAGMA_STRINGIFY_(s) #s
-#  define PRAGMA_JOIN_STRINGIFY_(a,b) PRAGMA_STRINGIFY_(a ## b)
 /* Support for macro-generated pragmas (c99) */
 #  define PRAGMA_(x) _Pragma (#x)
 #  ifdef __clang__
@@ -72,15 +70,15 @@
 /* we have push/pop support */
 #    define DISABLE_GCC_WARNING(warningopt) \
           PRAGMA_DIAGNOSTIC_(push) \
-          PRAGMA_DIAGNOSTIC_(ignored PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
+          PRAGMA_DIAGNOSTIC_(ignored warningopt)
 #    define ENABLE_GCC_WARNING(warningopt) \
           PRAGMA_DIAGNOSTIC_(pop)
 #else /* !(defined(__clang__) || GCC_VERSION >= 406) */
 /* older version of gcc: no push/pop support. */
 #    define DISABLE_GCC_WARNING(warningopt) \
-         PRAGMA_DIAGNOSTIC_(ignored PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
+         PRAGMA_DIAGNOSTIC_(ignored warningopt)
 #    define ENABLE_GCC_WARNING(warningopt) \
-         PRAGMA_DIAGNOSTIC_(warning PRAGMA_JOIN_STRINGIFY_(-W,warningopt))
+         PRAGMA_DIAGNOSTIC_(warning warningopt)
 #endif /* defined(__clang__) || GCC_VERSION >= 406 */
 #else /* !defined(__GNUC__) */
 /* not gcc at all */
@@ -194,8 +192,8 @@
 /** Macro: yield a pointer to the field at position <b>off</b> within the
  * structure <b>st</b>.  Example:
  * <pre>
- *   struct a { int foo; int bar; } x;
- *   ptrdiff_t bar_offset = offsetof(struct a, bar);
+ *   struct a_t { int foo; int bar; } x;
+ *   ptrdiff_t bar_offset = offsetof(struct a_t, bar);
  *   int *bar_p = STRUCT_VAR_P(&x, bar_offset);
  *   *bar_p = 3;
  * </pre>
@@ -205,10 +203,10 @@
 /** Macro: yield a pointer to an enclosing structure given a pointer to
  * a substructure at offset <b>off</b>. Example:
  * <pre>
- *   struct base { ... };
- *   struct subtype { int x; struct base b; } x;
- *   struct base *bp = &x.base;
- *   struct *sp = SUBTYPE_P(bp, struct subtype, b);
+ *   struct base_t { ... };
+ *   struct subtype_t { int x; struct base_t b; } x;
+ *   struct base_t *bp = &x.base;
+ *   struct *sp = SUBTYPE_P(bp, struct subtype_t, b);
  * </pre>
  */
 #define SUBTYPE_P(p, subtype, basemember) \
@@ -229,4 +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 /* defined(__COVERITY__) || defined(__clang_analyzer__) */
+
 #endif /* !defined(TOR_COMPAT_COMPILER_H) */
diff --git a/src/lib/cc/ctassert.h b/src/lib/cc/ctassert.h
index bedf0b83a6..d9d3aa40b0 100644
--- a/src/lib/cc/ctassert.h
+++ b/src/lib/cc/ctassert.h
@@ -46,7 +46,7 @@
 
 #define CTASSERT_EXPN(x, a, b) CTASSERT_DECL(x, a, b)
 #define CTASSERT_DECL(x, a, b) \
-  typedef char tor_ctassert_##a##_##b[(x) ? 1 : -1] ATTR_UNUSED
+  typedef char tor_ctassert_##a##_##b[(x) ? 1 : -1] ATTR_UNUSED; EAT_SEMICOLON
 
 #endif /* __STDC_VERSION__ >= 201112L */
 
diff --git a/src/lib/cc/include.am b/src/lib/cc/include.am
index 1aa722dd82..d2a415e956 100644
--- a/src/lib/cc/include.am
+++ b/src/lib/cc/include.am
@@ -3,4 +3,5 @@
 noinst_HEADERS += \
 	src/lib/cc/compat_compiler.h \
 	src/lib/cc/ctassert.h \
+	src/lib/cc/tokpaste.h \
 	src/lib/cc/torint.h
diff --git a/src/lib/cc/lib_cc.md b/src/lib/cc/lib_cc.md
new file mode 100644
index 0000000000..bd49005ba2
--- /dev/null
+++ b/src/lib/cc/lib_cc.md
@@ -0,0 +1,2 @@
+@dir /lib/cc
+@brief lib/cc: Macros for managing the C compiler and language.
diff --git a/src/lib/cc/tokpaste.h b/src/lib/cc/tokpaste.h
new file mode 100644
index 0000000000..068621b5bd
--- /dev/null
+++ b/src/lib/cc/tokpaste.h
@@ -0,0 +1,30 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file tokpaste.h
+ * @brief Token-pasting macros.
+ **/
+
+#ifndef TOR_LIB_CC_TOKPASTE_H
+#define TOR_LIB_CC_TOKPASTE_H
+
+/**
+ * Concatenate `a` and `b` in a way that allows their result itself to be
+ * expanded by the preprocessor.
+ *
+ * Ordinarily you could just say `a ## b` in a macro definition.  But doing so
+ * results in a symbol which the preprocessor will not then expand.  If you
+ * wanted to use `a ## b` to create the name of a macro and have the
+ * preprocessor expand _that_ macro, you need to have another level of
+ * indirection, as this macro provides.
+ **/
+#define PASTE(a,b) PASTE__(a,b)
+
+/** Helper for PASTE(). */
+#define PASTE__(a,b) a ## b
+
+#endif /* !defined(TOR_LIB_CC_TOKPASTE_H) */
diff --git a/src/lib/cc/torint.h b/src/lib/cc/torint.h
index 94b79d30a1..cef1482bdc 100644
--- a/src/lib/cc/torint.h
+++ b/src/lib/cc/torint.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**