bc: support void functions (GNU compat)

function                                             old     new   delta
xc_program_print                                       -     689    +689
zxc_vm_process                                       814     869     +55
zxc_program_exec                                    4098    4116     +18
zxc_program_assign                                   385     392      +7
bc_result_free                                        43      46      +3
zxc_program_binOpPrep                                243     245      +2
zdc_program_execStr                                  518     520      +2
zxc_program_print                                    683       -    -683
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 6/0 up/down: 776/-683)           Total: 93 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 73 insertions, 19 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index e497b0d02..69d3920c0 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -5,7 +5,6 @@
  * Original code copyright (c) 2018 Gavin D. Howard and contributors.
  */
 //TODO: GNU extensions:
-// support "define void f()..."
 // support "define f(*param[])" - "pass array by reference" syntax
 
 #define DEBUG_LEXER   0
@@ -344,10 +343,12 @@ typedef struct BcFunc {
         IF_BC(BcVec strs;)
         IF_BC(BcVec consts;)
         IF_BC(size_t nparams;)
+        IF_BC(bool voidfunc;)
 } BcFunc;
 
 typedef enum BcResultType {
         XC_RESULT_TEMP,
+        IF_BC(BC_RESULT_VOID,) // same as TEMP, but INST_PRINT will ignore it
 
         XC_RESULT_VAR,
         XC_RESULT_ARRAY_ELEM,
@@ -2451,11 +2452,12 @@ static void dc_result_copy(BcResult *d, BcResult *src)
                         d->d.id.name = xstrdup(src->d.id.name);
                         break;
                 case XC_RESULT_CONSTANT:
-                IF_BC(case BC_RESULT_LAST:)
-                IF_BC(case BC_RESULT_ONE:)
                 case XC_RESULT_STR:
                         memcpy(&d->d.n, &src->d.n, sizeof(BcNum));
                         break;
+                default: // placate compiler
+                        // BC_RESULT_VOID, BC_RESULT_LAST, BC_RESULT_ONE - do not happen
+                        break;
         }
 }
 #endif // ENABLE_DC
@@ -2466,6 +2468,7 @@ static FAST_FUNC void bc_result_free(void *result)
 
         switch (r->t) {
                 case XC_RESULT_TEMP:
+                IF_BC(case BC_RESULT_VOID:)
                 case XC_RESULT_IBASE:
                 case XC_RESULT_SCALE:
                 case XC_RESULT_OBASE:
@@ -4123,6 +4126,7 @@ static BC_STATUS zbc_parse_return(void)
         if (t == XC_LEX_NLINE || t == BC_LEX_SCOLON || t == BC_LEX_RBRACE)
                 xc_parse_push(BC_INST_RET0);
         else {
+//TODO: if (p->func->voidfunc) ERROR
                 s = zbc_parse_expr(0);
                 if (s) RETURN_STATUS(s);
 
@@ -4374,7 +4378,7 @@ static BC_STATUS zbc_parse_funcdef(void)
 {
         BcParse *p = &G.prs;
         BcStatus s;
-        bool var, comma = false;
+        bool var, comma, voidfunc;
         char *name;
 
         dbg_lex_enter("%s:%d entered", __func__, __LINE__);
@@ -4383,17 +4387,34 @@ static BC_STATUS zbc_parse_funcdef(void)
         if (p->lex != XC_LEX_NAME)
                 RETURN_STATUS(bc_error_bad_function_definition());
 
-        name = xstrdup(p->lex_strnumbuf.v);
-        p->fidx = bc_program_addFunc(name);
-        p->func = xc_program_func(p->fidx);
+        // To be maximally both POSIX and GNU-compatible,
+        // "void" is not treated as a normal keyword:
+        // you can have variable named "void", and even a function
+        // named "void": "define void() { return 6; }" is ok.
+        // _Only_ "define void f() ..." syntax treats "void"
+        // specially.
+        voidfunc = (strcmp(p->lex_strnumbuf.v, "void") == 0);
 
         s = zxc_lex_next();
         if (s) RETURN_STATUS(s);
+
+        voidfunc = (voidfunc && p->lex == XC_LEX_NAME);
+        if (voidfunc) {
+                s = zxc_lex_next();
+                if (s) RETURN_STATUS(s);
+        }
+
         if (p->lex != BC_LEX_LPAREN)
                 RETURN_STATUS(bc_error_bad_function_definition());
+
+        p->fidx = bc_program_addFunc(xstrdup(p->lex_strnumbuf.v));
+        p->func = xc_program_func(p->fidx);
+        p->func->voidfunc = voidfunc;
+
         s = zxc_lex_next();
         if (s) RETURN_STATUS(s);
 
+        comma = false;
         while (p->lex != BC_LEX_RPAREN) {
                 if (p->lex != XC_LEX_NAME)
                         RETURN_STATUS(bc_error_bad_function_definition());
@@ -4442,7 +4463,7 @@ static BC_STATUS zbc_parse_funcdef(void)
         // Prevent "define z()<newline>" from being interpreted as function with empty stmt as body
         s = zbc_lex_skip_if_at_NLINE();
         if (s) RETURN_STATUS(s);
-        //GNU bc requires a {} block even if function body has single stmt, enforce this?
+        // GNU bc requires a {} block even if function body has single stmt, enforce this
         if (p->lex != BC_LEX_LBRACE)
                 RETURN_STATUS(bc_error("function { body } expected"));
 
@@ -5127,6 +5148,7 @@ static BC_STATUS zxc_program_num(BcResult *r, BcNum **num)
         switch (r->t) {
         case XC_RESULT_STR:
         case XC_RESULT_TEMP:
+        IF_BC(case BC_RESULT_VOID:)
         case XC_RESULT_IBASE:
         case XC_RESULT_SCALE:
         case XC_RESULT_OBASE:
@@ -5584,22 +5606,32 @@ static BC_STATUS zxc_num_print(BcNum *n, bool newline)
 }
 #define zxc_num_print(...) (zxc_num_print(__VA_ARGS__) COMMA_SUCCESS)
 
-static BC_STATUS zxc_program_print(char inst, size_t idx)
+#if !ENABLE_DC
+// for bc, idx is always 0
+#define xc_program_print(inst, idx) \
+        xc_program_print(inst)
+#endif
+static BC_STATUS xc_program_print(char inst, size_t idx)
 {
         BcStatus s;
         BcResult *r;
         BcNum *num;
-        bool pop = (inst != XC_INST_PRINT);
+        IF_NOT_DC(size_t idx = 0);
 
         if (!STACK_HAS_MORE_THAN(&G.prog.results, idx))
                 RETURN_STATUS(bc_error_stack_has_too_few_elements());
 
         r = bc_vec_item_rev(&G.prog.results, idx);
+#if ENABLE_BC
+        if (inst == XC_INST_PRINT && r->t == BC_RESULT_VOID)
+                // void function's result on stack, ignore
+                RETURN_STATUS(BC_STATUS_SUCCESS);
+#endif
         s = zxc_program_num(r, &num);
         if (s) RETURN_STATUS(s);
 
         if (BC_PROG_NUM(r, num)) {
-                s = zxc_num_print(num, !pop);
+                s = zxc_num_print(num, /*newline:*/ inst == XC_INST_PRINT);
 #if ENABLE_BC
                 if (!s && IS_BC) bc_num_copy(&G.prog.last, num);
 #endif
@@ -5622,11 +5654,11 @@ static BC_STATUS zxc_program_print(char inst, size_t idx)
                 }
         }
 
-        if (!s && pop) bc_vec_pop(&G.prog.results);
+        if (!s && inst != XC_INST_PRINT) bc_vec_pop(&G.prog.results);
 
         RETURN_STATUS(s);
 }
-#define zxc_program_print(...) (zxc_program_print(__VA_ARGS__) COMMA_SUCCESS)
+#define zxc_program_print(...) (xc_program_print(__VA_ARGS__) COMMA_SUCCESS)
 
 static BC_STATUS zxc_program_negate(void)
 {
@@ -5790,8 +5822,12 @@ static BC_STATUS zxc_program_assign(char inst)
         }
 #endif
 
-        if (left->t == XC_RESULT_CONSTANT || left->t == XC_RESULT_TEMP)
+        if (left->t == XC_RESULT_CONSTANT
+         || left->t == XC_RESULT_TEMP
+        IF_BC(|| left->t == BC_RESULT_VOID)
+        ) {
                 RETURN_STATUS(bc_error_bad_assignment());
+        }
 
 #if ENABLE_BC
         if (assign)
@@ -6019,6 +6055,9 @@ static BC_STATUS zbc_program_return(char inst)
         size_t i;
         BcInstPtr *ip = bc_vec_top(&G.prog.exestack);
 
+        f = xc_program_func(ip->func);
+
+        res.t = XC_RESULT_TEMP;
         if (inst == XC_INST_RET) {
                 // bc needs this for e.g. RESULT_CONSTANT ("return 5")
                 // because bc constants are per-function.
@@ -6032,19 +6071,17 @@ static BC_STATUS zbc_program_return(char inst)
                 bc_num_init(&res.d.n, num->len);
                 bc_num_copy(&res.d.n, num);
                 bc_vec_pop(&G.prog.results);
-        //} else if (f->void_func) {
-                //prepare "void" result in res
         } else {
+                if (f->voidfunc)
+                        res.t = BC_RESULT_VOID;
                 bc_num_init_DEF_SIZE(&res.d.n);
                 //bc_num_zero(&res.d.n); - already is
         }
-        res.t = XC_RESULT_TEMP;
         bc_vec_push(&G.prog.results, &res);
 
         bc_vec_pop(&G.prog.exestack);
 
         // We need to pop arguments as well, so this takes that into account.
-        f = xc_program_func(ip->func);
         a = (void*)f->autos.v;
         for (i = 0; i < f->autos.len; i++, a++) {
                 BcVec *v;
@@ -6568,7 +6605,7 @@ static BC_STATUS zxc_program_exec(void)
                 case XC_INST_PRINT:
                 case XC_INST_PRINT_POP:
                 case XC_INST_PRINT_STR:
-                        dbg_exec("XC_INST_PRINTxyz:");
+                        dbg_exec("XC_INST_PRINTxyz(%d):", inst - XC_INST_PRINT);
                         s = zxc_program_print(inst, 0);
                         break;
                 case XC_INST_STR:
diff --git a/testsuite/bc.tests b/testsuite/bc.tests
index 0a8222be6..3fde60a2c 100755
--- a/testsuite/bc.tests
+++ b/testsuite/bc.tests
@@ -123,6 +123,23 @@ testing "bc define with body on next line" \
         "8\n9\n" \
         "" "define w()\n{ auto z; return 8; }\nw()\n9"
 
+testing "bc void function" \
+        "bc" \
+        "void9\n" \
+        "" "define void w() {print \"void\"}\nw()\n9"
+
+# Extra POSIX compat - GNU bc does not allow this
+testing "bc function named 'void'" \
+        "bc" \
+        "void0\n9\n" \
+        "" "define void() {print \"void\"}\nvoid()\n9"
+
+# Extra POSIX compat - GNU bc does not allow this
+testing "bc variable named 'void'" \
+        "bc" \
+        "6\n9\n" \
+        "" "void=6\nvoid\n9"
+
 testing "bc if(cond)<NL>" \
         "bc" \
         "9\n" \