Use static declaration for undeclared variable

NEWS.md

@@ -1,5 +1,7 @@
 # later 1.3.1.9000
 
+* Set file-level variables as `static` to avoid triggering `-Wmissing-variable-declarations` (@MichaelChirico, #163)
+
 * Fixed `unused varfiable` compiler warning. (@MichaelChirico, #176)
 
 # later 1.3.1

src/callback_registry.cpp

@@ -6,7 +6,7 @@
 #include "callback_registry.h"
 #include "debug.h"
 
-std::atomic<uint64_t> nextCallbackId(1);
+static std::atomic<uint64_t> nextCallbackId(1);
 
 // ============================================================================
 // Invoke functions
@@ -21,8 +21,8 @@ enum InvokeResult {
 };
 
 // This is set by invoke_c(). I
-InvokeResult last_invoke_result;
-std::string last_invoke_message;
+static InvokeResult last_invoke_result;
+static std::string last_invoke_message;
 
 // A wrapper for calling R_CheckUserInterrupt via R_ToplevelExec.
 void checkInterruptFn(void*) {

src/later_posix.cpp

@@ -21,21 +21,21 @@ extern void* R_GlobalContext;
 extern void* R_TopLevelContext;
 
 // Whether we have initialized the input handler.
-int initialized = 0;
+static int initialized = 0;
 
 // The handles to the read and write ends of a pipe. We use this pipe
 // to signal R's input handler callback mechanism that we want to be
 // called back.
-int pipe_in  = -1;
-int pipe_out = -1;
+static int pipe_in  = -1;
+static int pipe_out = -1;
 
-int dummy_pipe_in  = -1;
-int dummy_pipe_out = -1;
+static int dummy_pipe_in  = -1;
+static int dummy_pipe_out = -1;
 
 // Whether the file descriptor is ready for reading, i.e., whether
 // the input handler callback is scheduled to be called. We use this
 // to avoid unnecessarily writing to the pipe.
-bool hot = false;
+static bool hot = false;
 // This mutex protects reading/writing of `hot` and of reading from/writing to
 // the pipe.
 Mutex m(tct_mtx_plain);