nasm: fix the combination -E -MD, handle -MD without a filename

-E -MD should work and output a dependency file.
-MD can be used without a filename; there is a default filename or
-\c{-MF} can be used.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

asm/nasm.c

@@ -136,9 +136,9 @@ static const struct forwrefinfo *forwref;
 static const struct preproc_ops *preproc;
 static StrList *include_path;
 
-#define OP_NORMAL           (1u << 0)
-#define OP_PREPROCESS       (1u << 1)
-#define OP_DEPEND           (1u << 2)
+#define OP_NORMAL           (1U << 0)
+#define OP_PREPROCESS       (1U << 1)
+#define OP_DEPEND           (1U << 2)
 
 static unsigned int operating_mode;
 
@@ -509,9 +509,17 @@ int main(int argc, char **argv)
     /* Save away the default state of warnings */
     memcpy(warning_state_init, warning_state, sizeof warning_state);
 
+    /* Dependency filename if we are also doing other things */
+    if (!depend_file && (operating_mode & ~OP_DEPEND)) {
+        if (outname)
+            depend_file = nasm_strcat(outname, ".d");
+        else
+            depend_file = filename_set_extension(inname, ".d");
+    }
+
     /*
      * If no output file name provided and this
-     * is a preprocess mode, we're perfectly
+     * is preprocess mode, we're perfectly
      * fine to output into stdout.
      */
     if (!outname && !(operating_mode & OP_PREPROCESS)) {
@@ -524,13 +532,12 @@ int main(int argc, char **argv)
         }
     }
 
-    depend_ptr = (depend_file || (operating_mode & OP_DEPEND))
-        ? &depend_list : NULL;
+    depend_ptr = (operating_mode & OP_DEPEND) ? &depend_list : NULL;
 
     if (!depend_target)
         depend_target = quote_for_make(outname);
 
-    if (operating_mode & OP_DEPEND) {
+    if (!(operating_mode & (OP_PREPROCESS|OP_NORMAL))) {
             char *line;
 
             if (depend_missing_ok)
@@ -1077,9 +1084,11 @@ static bool process_arg(char *p, char *q, int pass)
                     depend_emit_phony = true;
                     break;
                 case 'D':
-                    operating_mode = OP_NORMAL;
-                    depend_file = q;
-                    advance = true;
+                    operating_mode |= OP_DEPEND;
+                    if (q && (q[0] != '-' || q[1] == '\0')) {
+                        depend_file = q;
+                        advance = true;
+                    }
                     break;
                 case 'F':
                     depend_file = q;

doc/changes.src

@@ -25,6 +25,12 @@ or hexadecimal floating-point having at least 32, 11, or 8 mantissa
 digits could produce slightly incorrect results under very specific
 conditions.
 
+\b Support \c{-MD} without a filename, for \c{gcc}
+compatibility. \c{-MF} can be used to set the dependencies output
+filename. See \k{opt-MD}.
+
+\b Fix \c{-E} in combination with \c{-MD}. See \k{opt-E}.
+
 \S{cl-2.14} Version 2.14
 
 \b Changed \c{-I} option semantics by adding a trailing path separator

doc/nasmdoc.src

@@ -496,6 +496,15 @@ updated dependencies with every assembly session.  For example:
 
 \c nasm -f elf -o myfile.o -MD myfile.dep myfile.asm
 
+If the argument after \c{-MD} is an option rather than a filename,
+then the output filename is the first applicable one of:
+
+\b the filename set in the \c{-MF} option;
+
+\b the output filename from the \c{-o} option with \c{.d} appended;
+
+\b the input filename with the extension set to \c{.d}.
+
 
 \S{opt-MT} The \i\c{-MT} Option: Dependency Target Name