refs #9880 show index and bound in lots of `index out of bounds` errors

4 files changed, 19 insertions, 5 deletions

diff --git a/lib/pure/collections/sharedstrings.nim b/lib/pure/collections/sharedstrings.nim
index 7e9de4b73..b283cd4b1 100644
--- a/lib/pure/collections/sharedstrings.nim
+++ b/lib/pure/collections/sharedstrings.nim
@@ -12,6 +12,8 @@
 type
   UncheckedCharArray = UncheckedArray[char]
 
+import system/helpers2
+
 type
   Buffer = ptr object
     refcount: int
@@ -49,11 +51,11 @@ proc len*(s: SharedString): int = s.len
 
 proc `[]`*(s: SharedString; i: Natural): char =
   if i < s.len: result = s.buffer.data[i+s.first]
-  else: raise newException(IndexError, "index out of bounds")
+  else: raise newException(IndexError, formatErrorIndexBound(i, s.len-1))
 
 proc `[]=`*(s: var SharedString; i: Natural; value: char) =
   if i < s.len: s.buffer.data[i+s.first] = value
-  else: raise newException(IndexError, "index out of bounds")
+  else: raise newException(IndexError, formatErrorIndexBound(i, s.len-1))
 
 proc `[]`*(s: SharedString; ab: HSlice[int, int]): SharedString =
   #incRef(src.buffer)
diff --git a/lib/pure/subexes.nim b/lib/pure/subexes.nim
index d103af710..638e71f04 100644
--- a/lib/pure/subexes.nim
+++ b/lib/pure/subexes.nim
@@ -17,7 +17,7 @@
 
 from strutils import parseInt, cmpIgnoreStyle, Digits
 include "system/inclrtl"
-
+import system/helpers2
 
 proc findNormalized(x: string, inArray: openarray[string]): int =
   var i = 0
@@ -85,7 +85,7 @@ proc getFormatArg(p: var FormatParser, a: openArray[string]): int =
     result = parseInt(a[result])-1
   else:
     raiseInvalidFormat("'#', '$', number or identifier expected")
-  if result >=% a.len: raiseInvalidFormat("index out of bounds: " & $result)
+  if result >=% a.len: raiseInvalidFormat(formatErrorIndexBound(result, a.len))
   p.i = i
 
 proc scanDollar(p: var FormatParser, a: openarray[string], s: var string) {.
diff --git a/lib/system/chcks.nim b/lib/system/chcks.nim
index d3651f659..6f4e8ce37 100644
--- a/lib/system/chcks.nim
+++ b/lib/system/chcks.nim
@@ -8,6 +8,7 @@
 #
 
 # Implementation of some runtime checks.
+import system/helpers2
 
 proc raiseRangeError(val: BiggestInt) {.compilerproc, noinline.} =
   when hostOS == "standalone":
@@ -15,6 +16,12 @@ proc raiseRangeError(val: BiggestInt) {.compilerproc, noinline.} =
   else:
     sysFatal(RangeError, "value out of range: ", $val)
 
+proc raiseIndexError3(i, a, b: int) {.compilerproc, noinline.} =
+  sysFatal(IndexError, formatErrorIndexBound(i, a, b))
+
+proc raiseIndexError2(i, n: int) {.compilerproc, noinline.} =
+  sysFatal(IndexError, formatErrorIndexBound(i, n))
+
 proc raiseIndexError() {.compilerproc, noinline.} =
   sysFatal(IndexError, "index out of bounds")
 
@@ -25,7 +32,7 @@ proc chckIndx(i, a, b: int): int =
   if i >= a and i <= b:
     return i
   else:
-    raiseIndexError()
+    raiseIndexError3(i, a, b)
 
 proc chckRange(i, a, b: int): int =
   if i >= a and i <= b:
diff --git a/lib/system/helpers2.nim b/lib/system/helpers2.nim
new file mode 100644
index 000000000..1c9e7c068
--- /dev/null
+++ b/lib/system/helpers2.nim
@@ -0,0 +1,5 @@
+template formatErrorIndexBound*[T](i, a, b: T): string =
+  "index out of bounds: (a:" & $a & ") <= (i:" & $i & ") <= (b:" & $b & ") "
+
+template formatErrorIndexBound*[T](i, n: T): string =
+  "index out of bounds: (i:" & $i & ") <= (n:" & $n & ") "