ref: 49aac2961d01a395d60b6eeeb7467021b43498f6
parent: 3741bd46171a143c5549422e8f55a2933b59eb97
author: Rangi <remy.oukaour+rangi42@gmail.com>
date: Wed Mar 31 06:00:21 EDT 2021
Warn about backwards FOR loops with -Wbackwards-for (-Wall) Fixes #816
--- a/include/asm/warning.h
+++ b/include/asm/warning.h
@@ -15,6 +15,7 @@
enum WarningID {WARNING_ASSERT, /* Assertions */
+ WARNING_BACKWARDS_FOR, /* `for` loop with backwards range */
WARNING_BUILTIN_ARG, /* Invalid args to builtins */
WARNING_CHARMAP_REDEF, /* Charmap entry re-definition */
WARNING_DIV, /* Division undefined behavior */
--- a/src/asm/fstack.c
+++ b/src/asm/fstack.c
@@ -487,6 +487,10 @@
else if (step == 0)
error("FOR cannot have a step value of 0\n");+ if ((step > 0 && start > stop) || (step < 0 && start < stop))
+ warning(WARNING_BACKWARDS_FOR, "FOR goes backwards from %d to %d by %d\n",
+ start, stop, step);
+
if (count == 0)
return;
if (!newReptContext(reptLineNo, body, size))
--- a/src/asm/rgbasm.1
+++ b/src/asm/rgbasm.1
@@ -189,7 +189,7 @@
prefix, entries are listed alphabetically.
.Bl -tag -width Ds
.It Fl Wno-assert
-Warns when
+Warn when
.Ic WARN Ns No -type
assertions fail. (See
.Dq Aborting the assembly process
@@ -197,6 +197,12 @@
.Xr rgbasm 5
for
.Ic ASSERT ) .
+.It Fl Wbackwards-for
+Warn when
+.Ic FOR
+loops have their start and stop values switched according to the step value.
+This warning is enabled by
+.Fl Wall .
.It Fl Wbuiltin-args
Warn about incorrect arguments to built-in functions, such as
.Fn STRSUB
@@ -239,7 +245,7 @@
directive are encountered.
.It Fl Wshift
Warn when shifting right a negative value.
-Use a division by 2^N instead.
+Use a division by 2**N instead.
.It Fl Wshift-amount
Warn when a shift's operand is negative or greater than 32.
.It Fl Wno-truncation
--- a/src/asm/warning.c
+++ b/src/asm/warning.c
@@ -30,6 +30,7 @@
static enum WarningState const defaultWarnings[NB_WARNINGS] = {[WARNING_ASSERT] = WARNING_ENABLED,
+ [WARNING_BACKWARDS_FOR] = WARNING_DISABLED,
[WARNING_BUILTIN_ARG] = WARNING_DISABLED,
[WARNING_CHARMAP_REDEF] = WARNING_DISABLED,
[WARNING_DIV] = WARNING_DISABLED,
@@ -72,6 +73,7 @@
static char const *warningFlags[NB_WARNINGS_ALL] = {"assert",
+ "backwards-for",
"builtin-args",
"charmap-redef",
"div",
@@ -100,6 +102,7 @@
/* Warnings that probably indicate an error */
static uint8_t const _wallCommands[] = {+ WARNING_BACKWARDS_FOR,
WARNING_BUILTIN_ARG,
WARNING_CHARMAP_REDEF,
WARNING_EMPTY_DATA_DIRECTIVE,
@@ -119,6 +122,7 @@
/* Literally everything. Notably useful for testing */
static uint8_t const _weverythingCommands[] = {+ WARNING_BACKWARDS_FOR,
WARNING_BUILTIN_ARG,
WARNING_DIV,
WARNING_EMPTY_DATA_DIRECTIVE,
--- a/test/asm/for.asm
+++ b/test/asm/for.asm
@@ -8,11 +8,15 @@
endr
for v, 2, 1
- print "unreached"
+ print "backwards"
endr
for v, 1, 2, 0
print "unreached"
+endr
+
+for v, 1, 2, -1
+ print "backwards"
endr
for x, 1, 5+1
--- a/test/asm/for.err
+++ b/test/asm/for.err
@@ -1,6 +1,10 @@
+warning: for.asm(12): [-Wbackwards-for]
+ FOR goes backwards from 2 to 1 by 1
ERROR: for.asm(16):
FOR cannot have a step value of 0
-ERROR: for.asm(41) -> for.asm::REPT~4(47):
- 'v' already defined as constant at for.asm(41) -> for.asm::REPT~4(45)
-FATAL: for.asm(41) -> for.asm::REPT~4(47):
+warning: for.asm(20): [-Wbackwards-for]
+ FOR goes backwards from 1 to 2 by -1
+ERROR: for.asm(45) -> for.asm::REPT~4(51):
+ 'v' already defined as constant at for.asm(45) -> for.asm::REPT~4(49)
+FATAL: for.asm(45) -> for.asm::REPT~4(51):
Failed to update FOR symbol value