Complain about control characters that are not white space.

Bitten by invisible chars too many times.

R=ken
OCL=24024
CL=24024

diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index 7e16fa92797c9bdf093c6cf8d76d84de242bea5f..a4f12313e07ba158445c72d1742afaa7df014c7c 100644 (file)
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -299,6 +299,21 @@ cannedimports(char *file, char *cp)
        inimportsys = 1;
 }
 
+int
+isfrog(int c) {
+       // complain about possibly invisible control characters
+       if(c < 0)
+               return 1;
+       if(c < ' ') {
+               if(c == ' ' || c == '\n' || c== '\r' || c == '\t')      // good white space
+                       return 0;
+               return 1;
+       }
+       if(0x80 <= c && c <=0xa0)       // unicode block including unbreakable space.
+               return 1;
+       return 0;
+}
+
 int32
 yylex(void)
 {
@@ -645,6 +660,10 @@ lx:
                DBG("%L lex: TOKEN %s\n", lineno, lexname(c));
        else
                DBG("%L lex: TOKEN '%c'\n", lineno, c);
+       if(isfrog(c)) {
+               yyerror("illegal character 0x%ux", c);
+               goto l0;
+       }
        return c;
 
 asop:
@@ -661,8 +680,14 @@ talph:
                if(c >= Runeself) {
                        for(c1=0;;) {
                                cp[c1++] = c;
-                               if(fullrune(cp, c1))
+                               if(fullrune(cp, c1)) {
+                                       chartorune(&rune, cp);
+                                        if(isfrog(rune)) {
+                                               yyerror("illegal character 0x%ux", rune);
+                                               goto l0;
+                                        }
                                        break;
+                               }
                                c = getc();
                        }
                        cp += c1;