Improve error message when an unknown SWIG directive is used

This previously gave the cryptic "Error: Syntax error in input(1).", but
now gives "Error: Unknown directive '%foo'."

CHANGES.current

@@ -5,6 +5,11 @@ See the RELEASENOTES file for a summary of changes in each release.
 Version 3.0.4 (in progress)
 ===========================
 
+2015-01-08: olly
+	    Improve error message when an unknown SWIG directive is used - this
+	    previously gave the cryptic "Error: Syntax error in input(1).", but
+	    now gives "Error: Unknown directive '%foo'."
+
 2015-01-08: olly
 	    Provide -cppext as a general command line option for setting the
 	    extension used for generated C++ files (previously it was specific

Examples/test-suite/errors/pp_unknowndirective.i

@@ -0,0 +1,7 @@
+%module xxx
+
+/* This used to give the rather cryptic "Syntax error in input(1)." prior to
+ * SWIG 3.0.4.  This testcase checks that the improved message is actually
+ * issued.
+ */
+%remane("typo") tyop;

Examples/test-suite/errors/pp_unknowndirective.stderr

@@ -0,0 +1 @@
+c_unknowndirective.i:7: Error: Unknown directive '%remane'.

Source/CParse/cparse.h

@@ -27,6 +27,7 @@ extern "C" {
   extern int cparse_cplusplus;
   extern int cparse_cplusplusout;
   extern int cparse_start_line;
+  extern String *cparse_unknown_directive;
 
   extern void Swig_cparse_cplusplus(int);
   extern void Swig_cparse_cplusplusout(int);

Source/CParse/cscanner.c

@@ -40,6 +40,9 @@ int cparse_cplusplus = 0;
 /* Generate C++ compatible code when wrapping C code */
 int cparse_cplusplusout = 0;
 
+/* To allow better error reporting */
+String *cparse_unknown_directive = 0;
+
 /* Private vars */
 static int scan_init = 0;
 static int num_brace = 0;
@@ -801,8 +804,11 @@ int yylex(void) {
       if (strcmp(yytext, "inline") == 0)
 	return (yylex());
 
-      /* SWIG directives */
     } else {
+      Delete(cparse_unknown_directive);
+      cparse_unknown_directive = NULL;
+
+      /* SWIG directives */
       if (strcmp(yytext, "%module") == 0)
 	return (MODULE);
       if (strcmp(yytext, "%insert") == 0)
@@ -878,6 +884,9 @@ int yylex(void) {
       }
       if (strcmp(yytext, "%warn") == 0)
 	return (WARN);
+
+      /* Note down the apparently unknown directive for error reporting. */
+      cparse_unknown_directive = Swig_copy_string(yytext);
     }
     /* Have an unknown identifier, as a last step, we'll do a typedef lookup on it. */
 

Source/CParse/parser.y

@@ -1510,7 +1510,11 @@ declaration    : swig_directive { $$ = $1; }
                | SEMI { $$ = 0; }
                | error {
                   $$ = 0;
-		  Swig_error(cparse_file, cparse_line,"Syntax error in input(1).\n");
+		  if (cparse_unknown_directive) {
+		      Swig_error(cparse_file, cparse_line, "Unknown directive '%s'.\n", cparse_unknown_directive);
+		  } else {
+		      Swig_error(cparse_file, cparse_line, "Syntax error in input(1).\n");
+		  }
 		  exit(1);
                }
 /* Out of class constructor/destructor declarations */