Merge pull request #1111 from ojwb/empty-arglist-macros

Fix handling of macro with empty argument list

CHANGES.current

@@ -6,6 +6,11 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 
 Version 4.0.0 (in progress)
 ===========================
+2017-10-07: olly
+	    Fix preprocessor handling of empty macro arguments to match that of
+	    C/C++ compilers.  Fixes https://github.com/swig/swig/pull/1111 and
+	    https://sourceforge.net/p/swig/bugs/826/
+
 2017-10-06: wsfulton
             [Python] Issue #1108. Fix platorm inconsistency in Python default argument handling.
             32 bit and 64 bit compiled versions of SWIG generated different Python files

Examples/test-suite/multiple_inheritance_shared_ptr.i

@@ -50,9 +50,9 @@
 %shared_ptr(Space::Bottom3)
 
 %include "swiginterface.i"
-SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(SWIGEMPTYHACK, Space::ABase1)
+SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(, Space::ABase1)
-SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(SWIGEMPTYHACK, Space::CBase1)
+SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(, Space::CBase1)
-SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(SWIGEMPTYHACK, Space::CBase2)
+SWIG_SHARED_PTR_INTERFACE_TYPEMAPS(, Space::CBase2)
 %interface_impl(Space::ABase1)
 %interface_impl(Space::CBase1)
 %interface_impl(Space::CBase2)

Examples/test-suite/preproc.i

@@ -388,3 +388,42 @@ TCX_PACKED (typedef struct tcxMessageBugImpl
 }) tcxMessageBug;
 %}
 
+// Regression tests for https://github.com/swig/swig/pull/1111
+%{
+static int foo_func(int x) { return x; }
+static int foo_func2() { return 0; }
+static int bar_func() { return 0; }
+static int baz_func(int a, int b, int c) { return a + b - c; }
+%}
+%inline %{
+#define FOO(X) int foo_func(X);
+#define FOO2(X) int foo_func2(X);
+#define BAR() int bar_func();
+#define BAR2() int bar_func2()
+#define BAZ(A,B,C) baz_func(A+0,B,C)
+#define FOOVAR(...) foo_func(__VA_ARGS__)
+#define BARVAR(...) bar_func(__VA_ARGS__)
+#define BAZVAR(...) baz_func(__VA_ARGS__)
+// This has probably always worked, but make sure that the fix to accept
+// an empty X doesn't cause this case to be incorrectly expanded:
+const int FOO = 7;
+// BAR was incorrectly expanded here, causing:
+// Error: Syntax error in input(1).
+const int BAR = 6;
+// This has probably always worked, but make sure that the fix to accept
+// an empty X doesn't stop a non-empty X from working:
+FOO(int x)
+// FOO() didn't used to get expanded here, causing:
+// Syntax error in input(1).
+FOO2()
+// Check BAR2() still gets expanded here.
+BAR2() {
+    // Regression test - this used to fail with:
+    // Error: Macro 'BAZ' expects 3 arguments
+    BAZ(,2,3);
+    BARVAR();
+    FOOVAR(1);
+    BAZVAR(1,2,3);
+    return 0;
+}
+%}

Lib/intrusive_ptr.i

@@ -44,18 +44,16 @@ struct SWIG_null_deleter {
 %#define SWIG_NO_NULL_DELETER_1
 }
 
-// Workaround empty first macro argument bug
-#define SWIGEMPTYHACK
 // Main user macro for defining intrusive_ptr typemaps for both const and non-const pointer types
 %define %intrusive_ptr(TYPE...)
 %feature("smartptr", noblock=1) TYPE { SWIG_SHARED_PTR_QNAMESPACE::shared_ptr< TYPE > }
-SWIG_INTRUSIVE_PTR_TYPEMAPS(SWIGEMPTYHACK, TYPE)
+SWIG_INTRUSIVE_PTR_TYPEMAPS(, TYPE)
 SWIG_INTRUSIVE_PTR_TYPEMAPS(const, TYPE)
 %enddef
 
 %define %intrusive_ptr_no_wrap(TYPE...)
 %feature("smartptr", noblock=1) TYPE { SWIG_SHARED_PTR_QNAMESPACE::shared_ptr< TYPE > }
-SWIG_INTRUSIVE_PTR_TYPEMAPS_NO_WRAP(SWIGEMPTYHACK, TYPE)
+SWIG_INTRUSIVE_PTR_TYPEMAPS_NO_WRAP(, TYPE)
 SWIG_INTRUSIVE_PTR_TYPEMAPS_NO_WRAP(const, TYPE)
 %enddef
 

Lib/shared_ptr.i

@@ -49,12 +49,10 @@ struct SWIG_null_deleter {
 }
 
 
-// Workaround empty first macro argument bug
-#define SWIGEMPTYHACK
 // Main user macro for defining shared_ptr typemaps for both const and non-const pointer types
 %define %shared_ptr(TYPE...)
 %feature("smartptr", noblock=1) TYPE { SWIG_SHARED_PTR_QNAMESPACE::shared_ptr< TYPE > }
-SWIG_SHARED_PTR_TYPEMAPS(SWIGEMPTYHACK, TYPE)
+SWIG_SHARED_PTR_TYPEMAPS(, TYPE)
 SWIG_SHARED_PTR_TYPEMAPS(const, TYPE)
 %enddef
 

Source/Preprocessor/cpp.c

@@ -640,13 +640,8 @@ static List *find_args(String *s, int ismacro, String *macro_name) {
       goto unterm;
     }
     Chop(str);
-    if (Len(args) || Len(str))
     Append(args, str);
     Delete(str);
-
-    /*    if (Len(str) && (c != ')'))
-       Append(args,str); */
-
     if (c == ')')
       return args;
     c = Getc(s);
@@ -817,11 +812,24 @@ static String *expand_macro(String *name, List *args, String *line_file) {
       Delete(vararg);
     }
   }
+
+  if (args && margs && Len(margs) == 0 && Len(args) == 1 && Len(Getitem(args, 0)) == 0) {
+    /* FOO() can invoke a macro defined as FOO(X) as well as one defined FOO().
+     *
+     * Handle this by removing the only argument if it's empty and the macro
+     * expects no arguments.
+     *
+     * We don't need to worry about varargs here - a varargs macro will always have
+     * Len(margs) >= 1, since the varargs are put in the final macro argument.
+     */
+    Delitem(args, 0);
+  }
+
   /* If there are arguments, see if they match what we were given */
-  if (args && (margs) && (Len(margs) != Len(args))) {
+  if (args && (!margs || Len(margs) != Len(args))) {
-    if (Len(margs) > (1 + isvarargs))
+    if (margs && Len(margs) > (1 + isvarargs))
       Swig_error(macro_start_file, macro_start_line, "Macro '%s' expects %d arguments\n", name, Len(margs) - isvarargs);
-    else if (Len(margs) == (1 + isvarargs))
+    else if (margs && Len(margs) == (1 + isvarargs))
       Swig_error(macro_start_file, macro_start_line, "Macro '%s' expects 1 argument\n", name);
     else
       Swig_error(macro_start_file, macro_start_line, "Macro '%s' expects no arguments\n", name);
@@ -830,7 +838,7 @@ static String *expand_macro(String *name, List *args, String *line_file) {
   }
 
   /* If the macro expects arguments, but none were supplied, we leave it in place */
-  if (!args && (margs) && Len(margs) > 0) {
+  if (!args && margs) {
     macro_level--;
     return NewString(name);
   }
@@ -1156,10 +1164,6 @@ static DOH *Preprocessor_replace(DOH *s) {
 	    args = find_args(s, 1, id);
 	    macro_additional_lines = Getline(s) - line;
 	    assert(macro_additional_lines >= 0);
-	    if (!Len(args)) {
-	      Delete(args);
-	      args = 0;
-	    }
 	  } else {
 	    args = 0;
 	  }