Issue a warning if no output file is specified.

ispc.cpp

@@ -389,7 +389,13 @@ Globals::Globals() {
 // SourcePos
 
 SourcePos::SourcePos(const char *n, int fl, int fc, int ll, int lc) {
-    name = n ? n : m->module->getModuleIdentifier().c_str();
+    name = n;
+    if (name == NULL) {
+        if (m != NULL)
+            name = m->module->getModuleIdentifier().c_str();
+        else
+            name = "(unknown)";
+    }
     first_line = fl;
     first_column = fc;
     last_line = ll != 0 ? ll : fl;

main.cpp

@@ -37,6 +37,7 @@
 
 #include "ispc.h"
 #include "module.h"
+#include "util.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <llvm/Support/PrettyStackTrace.h>
@@ -354,6 +355,11 @@ int main(int Argc, char *Argv[]) {
     if (debugSet && !optSet)
         g->opt.level = 0;
 
+    if (outFileName == NULL && headerFileName == NULL)
+        Warning(SourcePos(), "Warning: no output file or header file name "
+                "specified.  Program will be compiled and warnings/errors will "
+                "be issued, but no output will be generated.");
+
     return Module::CompileAndOutput(file, arch, cpu, target, generatePIC,
                                     ot, outFileName, headerFileName);
 }

util.cpp

@@ -267,7 +267,7 @@ Error(SourcePos p, const char *fmt, ...) {
     va_list args;
     va_start(args, fmt);
     lPrint("Error", p, fmt, args);
-    ++m->errorCount;
+    if (m != NULL) ++m->errorCount;
     va_end(args);
 }
 
@@ -292,7 +292,7 @@ Warning(SourcePos p, const char *fmt, ...) {
     va_list args;
     va_start(args, fmt);
     lPrint(g->warningsAsErrors ? "Error" : "Warning", p, fmt, args);
-    if (g->warningsAsErrors)
+    if (g->warningsAsErrors && m != NULL)
         ++m->errorCount;
     va_end(args);
 }