From 73d102b86a0df20aba266b1649637c354de1780d Mon Sep 17 00:00:00 2001
From: Stanislav Gromov <gromovstanislav@yandex.ru>
Date: Wed, 17 Jun 2020 19:06:26 +0800
Subject: [PATCH 1/3] Add a distinct error for division by zero

---
 source/compiler/sc3.c | 2 +-
 source/compiler/sc5.c | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/source/compiler/sc3.c b/source/compiler/sc3.c
index 46486997..0c69c595 100644
--- a/source/compiler/sc3.c
+++ b/source/compiler/sc3.c
@@ -644,7 +644,7 @@ static cell flooreddiv(cell a,cell b,int return_remainder)
   cell q,r;
 
   if (b==0) {
-    error(29);
+    error(94);  /* division by zero */
     return 0;
   } /* if */
   /* first implement truncated division in a portable way */
diff --git a/source/compiler/sc5.c b/source/compiler/sc5.c
index c5b31845..09c477ce 100644
--- a/source/compiler/sc5.c
+++ b/source/compiler/sc5.c
@@ -132,7 +132,8 @@ static char *errmsg[] = {
 /*090*/  "public functions may not return arrays (symbol \"%s\")\n",
 /*091*/  "ambiguous constant; tag override is required (symbol \"%s\")\n",
 /*092*/  "functions may not return arrays of unknown size (symbol \"%s\")\n",
-/*093*/  "\"__addressof\" operator is invalid in preprocessor expressions\n"
+/*093*/  "\"__addressof\" operator is invalid in preprocessor expressions\n",
+/*094*/  "division by zero\n"
 };
 
 static char *fatalmsg[] = {

From 8272c9fbb626aa9a27bb3b96bd9da23e92683a2c Mon Sep 17 00:00:00 2001
From: Stanislav Gromov <gromovstanislav@yandex.ru>
Date: Wed, 17 Jun 2020 19:24:32 +0800
Subject: [PATCH 2/3] Fix error 094 not being printed if the dividend is not a
 constant value

---
 source/compiler/sc3.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/source/compiler/sc3.c b/source/compiler/sc3.c
index 0c69c595..2ac50114 100644
--- a/source/compiler/sc3.c
+++ b/source/compiler/sc3.c
@@ -620,6 +620,10 @@ static void plnge2(void (*oper)(void),
     } /* if */
     /* ??? ^^^ should do same kind of error checking with functions */
 
+    /* If we're handling a division operation, make sure the divisor is not zero. */
+    if ((oper==os_div || oper==os_mod) && lval2->ident==iCONSTEXPR && lval2->constval==0)
+      error(94); /* division by zero */
+
     /* check whether an "operator" function is defined for the tag names
      * (a constant expression cannot be optimized in that case)
      */
@@ -643,10 +647,8 @@ static cell flooreddiv(cell a,cell b,int return_remainder)
 {
   cell q,r;
 
-  if (b==0) {
-    error(94);  /* division by zero */
+  if (b==0)
     return 0;
-  } /* if */
   /* first implement truncated division in a portable way */
   #define IABS(a)       ((a)>=0 ? (a) : (-a))
   q=IABS(a)/IABS(b);

From 313b071e3fb4a0c75bc3956112991151787af4e2 Mon Sep 17 00:00:00 2001
From: Stanislav Gromov <gromovstanislav@yandex.ru>
Date: Wed, 17 Jun 2020 19:59:59 +0800
Subject: [PATCH 3/3] Add tests

---
 source/compiler/tests/error_094.meta |  9 +++++++++
 source/compiler/tests/error_094.pwn  | 20 ++++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 source/compiler/tests/error_094.meta
 create mode 100644 source/compiler/tests/error_094.pwn

diff --git a/source/compiler/tests/error_094.meta b/source/compiler/tests/error_094.meta
new file mode 100644
index 00000000..fecd2763
--- /dev/null
+++ b/source/compiler/tests/error_094.meta
@@ -0,0 +1,9 @@
+{
+  'test_type': 'output_check',
+  'errors': """
+error_094.pwn(6) : error 094: division by zero
+error_094.pwn(7) : error 094: division by zero
+error_094.pwn(13) : error 094: division by zero
+error_094.pwn(14) : error 094: division by zero
+"""
+}
diff --git a/source/compiler/tests/error_094.pwn b/source/compiler/tests/error_094.pwn
new file mode 100644
index 00000000..81468763
--- /dev/null
+++ b/source/compiler/tests/error_094.pwn
@@ -0,0 +1,20 @@
+#include <console>
+
+main()
+{
+	// Case 1: Both operands are compile-time constants
+	printf("%d", 1 / 0); // error 094
+	printf("%d", 1 % 0); // error 094
+	printf("%d", 1 / 1);
+	printf("%d", 1 % 1);
+
+	// Case 2: Only the divisor is a constant
+	new var = 0;
+	printf("%d", var / 0); // error 094
+	printf("%d", var % 0); // error 094
+	printf("%d", var / 1);
+	printf("%d", var % 1);
+
+	printf("%d", 1 / var); // Just to make sure the error works only
+	printf("%d", 1 % var); // if the divisor is a constant value
+}