Add -7 option to compiler to enable ancient construct

Following commits add various funcitonality that is likely to be
unwanted for the most, but is vital to compile really old C code, such
as Seventh Edition UNIX code.

5 files changed, 49 insertions, 1 deletions

diff --git a/bcc/bcc.c b/bcc/bcc.c
index 574752c..dc68b46 100644
--- a/bcc/bcc.c
+++ b/bcc/bcc.c
@@ -103,7 +103,11 @@ struct opt_list {
 } * options;
 
 int opt_v, opt_V, opt_e, opt_x, opt_I, opt_L, opt_W, opt_i,
-    opt_O, opt_M, opt_f;
+    opt_O, opt_M, opt_f
+#ifndef VERY_SMALL_MEMORY
+, opt_7
+#endif
+;
 
 #ifdef DEFARCH
 int opt_arch = (DEFARCH != 0);
@@ -392,6 +396,10 @@ struct file_list * file;
 
    if (opt_arch<5 && !do_as)
       command_opt("-t");
+#ifndef VERY_SMALL_MEMORY
+   if (opt_7)
+       command_opt("-7");
+#endif
 
    command_opts('c');
    command_opts('C');
@@ -956,6 +964,9 @@ char ** argv;
       case 'L': opt_L++; break;
       case 'i': opt_i++; break;
       case 'f': opt_f++; break;
+#ifndef VERY_SMALL_MEMORY
+      case '7': opt_7++; break;
+#endif
 
       case 'W': opt_W++; break;
 
diff --git a/bcc/gencode.c b/bcc/gencode.c
index 91c524f..6c97e1d 100644
--- a/bcc/gencode.c
+++ b/bcc/gencode.c
@@ -81,6 +81,9 @@ PUBLIC bool_t arg1inreg = TRUE;
 PUBLIC store_pt calleemask = INDREG1 | INDREG2;
 PUBLIC bool_t callersaves = TRUE;
 PUBLIC char *callstring = "JSR\t>";
+#ifndef VERY_SMALL_MEMORY
+PUBLIC bool_t ancient = FALSE;
+#endif
 PUBLIC store_pt doubleargregs = DREG | INDREG0 | INDREG1 | INDREG2;
 PUBLIC store_pt doubleregs = DREG | INDREG0 | INDREG1 | INDREG2;
 PUBLIC store_pt doublreturnregs = DREG | INDREG0 | INDREG1 | INDREG2;
diff --git a/bcc/input.c b/bcc/input.c
index a17af4a..9ef19e3 100644
--- a/bcc/input.c
+++ b/bcc/input.c
@@ -12,6 +12,9 @@
 #include "sc.h"
 #include "scan.h"
 #include "table.h"
+#ifndef VERY_SMALL_MEMORY
+#include "parse.h"
+#endif
 
 #undef EXTERN
 #define EXTERN
@@ -539,6 +542,9 @@ char *argv[];
 #endif
 	    case 't':		/* print source code in asm output */
 	    case 'w':		/* watch location counter */
+#ifndef VERY_SMALL_MEMORY
+	    case '7':		/* accept ancient K&R code */
+#endif
 	    case 'O':		/* Optimisation. */
 		if (arg[2] == 0)
 		    flag[(int)arg[1]] = TRUE;
@@ -631,6 +637,13 @@ ts_s_includelist += sizeof *incnew;
 	definestring("__POS_INDEPENDENT__");
     }
 #endif
+#ifndef VERY_SMALL_MEMORY
+    if (flag['7'])
+    {
+	ancient = TRUE;
+	definestring("__ANCIENT__");
+    }
+#endif
     if (flag['O'])
     {
 	optimise = TRUE;
diff --git a/bcc/parse.h b/bcc/parse.h
index ab67f6c..429ca2a 100644
--- a/bcc/parse.h
+++ b/bcc/parse.h
@@ -17,3 +17,6 @@ EXTERN struct nodestruct *etptr;     /* ptr to next entry in expression tree */
 EXTERN struct symstruct *gvarsymptr; /* gsymptr for last identifier declared */
 EXTERN scopelev_t level;	/* scope level */
 				/* depends on zero init */
+#ifndef VERY_SMALL_MEMORY
+EXTERN bool_t ancient;		/* undersand ancient K&R */
+#endif
diff --git a/man/bcc.1 b/man/bcc.1
index 21a1d64..ea59492 100644
--- a/man/bcc.1
+++ b/man/bcc.1
@@ -197,6 +197,18 @@ don't include crt0.o in the link.
 don't pass
 .B -i
 to the linker so that it will create an impure executable.
+.TP
+.B -7
+Turn on ancient C mode (see CODE GENERATOR OPTIONS below).
+Among other things, this disables valuable
+error checks and even parses certain constructs incompatibly (e.g.
+.I =-
+is postdecrement instead of an assignment of a negative number)
+to later C standards, so this option should only be used with ancient
+code. To generate executables for a V7 variant you should tell
+linker to generate old a.out header with
+.B -X-7
+option.
 .P
 Other options are passed to the linker, in particular -lx, -M, -m, -s, -H.
 
@@ -249,6 +261,12 @@ print source code in assembly output
 .TP 
 .B -w
 print what cc1 thinks is the location counter in assembly output
+.TP
+.B -7
+Accept various obsolete construct for ancient C compilers, including
+Ritchie's Sixth Edition UNIX C compiler and Seventh Edition UNIX
+Portable C compiler. Enough of these compilers is emulated to compile
+all of Seventh Edition userspace and kernel.
 .P
 All the options except -D, -I and -o may be turned off by following the
 option letter by a '-'.  Options are processed left to right so the last