Error -> Defect for defects (#13908)

* Error -> Defect for defects

The distinction between Error and Defect is subjective,
context-dependent and somewhat arbitrary, so when looking at an
exception, it's hard to guess what it is - this happens often when
looking at a `raises` list _without_ opening the corresponding
definition and digging through layers of inheritance.

With the help of a little consistency in naming, it's at least possible
to start disentangling the two error types and the standard lib can set
a good example here.

compiler/ast.nim

@@ -290,7 +290,7 @@ type
     sfTemplateParam   # symbol is a template parameter
     sfCursor          # variable/field is a cursor, see RFC 177 for details
     sfInjectDestructors # whether the proc needs the 'injectdestructors' transformation
-    sfNeverRaises     # proc can never raise an exception, not even OverflowError
+    sfNeverRaises     # proc can never raise an exception, not even OverflowDefect
                       # or out-of-memory
 
   TSymFlags* = set[TSymFlag]

compiler/ccgexprs.nim

@@ -821,7 +821,7 @@ proc genFieldCheck(p: BProc, e: PNode, obj: Rope, field: PSym) =
     v.r.add(".")
     v.r.add(disc.sym.loc.r)
     genInExprAux(p, it, u, v, test)
-    let msg = genFieldError(field, disc.sym)
+    let msg = genFieldDefect(field, disc.sym)
     let strLit = genStringLiteral(p.module, newStrNode(nkStrLit, msg))
     if op.magic == mNot:
       linefmt(p, cpsStmts,

compiler/jsgen.nim

@@ -1131,7 +1131,7 @@ proc genCheckedFieldOp(p: PProc, n: PNode, addrTyp: PType, r: var TCompRes) =
 
   useMagic(p, "raiseFieldError")
   useMagic(p, "makeNimstrLit")
-  let msg = genFieldError(field, disc)
+  let msg = genFieldDefect(field, disc)
   lineF(p, "if ($1[$2.$3]$4undefined) { raiseFieldError(makeNimstrLit($5)); }$n",
     setx.res, tmp, disc.loc.r, if negCheck: ~"!==" else: ~"===",
     makeJSString(msg))
@@ -2343,7 +2343,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
   if r.kind != resCallee: r.kind = resNone
   #r.address = nil
   r.res = nil
-  
+
   case n.kind
   of nkSym:
     genSym(p, n, r)
@@ -2398,7 +2398,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
         n.len >= 1:
       genInfixCall(p, n, r)
     else:
-      genCall(p, n, r)    
+      genCall(p, n, r)
   of nkClosure: gen(p, n[0], r)
   of nkCurly: genSetConstr(p, n, r)
   of nkBracket: genArrayConstr(p, n, r)
@@ -2602,7 +2602,7 @@ proc myClose(graph: ModuleGraph; b: PPassContext, n: PNode): PNode =
       (code, map) = genSourceMap($(code), outFile.string)
       writeFile(outFile.string & ".map", $(%map))
     discard writeRopeIfNotEqual(code, outFile)
-    
+
 proc myOpen(graph: ModuleGraph; s: PSym): PPassContext =
   result = newModule(graph, s)
 

compiler/lexer.nim

@@ -571,7 +571,7 @@ proc getNumber(L: var TLexer, result: var TToken) =
         try:
           len = parseBiggestUInt(result.literal, iNumber)
         except ValueError:
-          raise newException(OverflowError, "number out of range: " & $result.literal)
+          raise newException(OverflowDefect, "number out of range: " & $result.literal)
         if len != result.literal.len:
           raise newException(ValueError, "invalid integer: " & $result.literal)
         result.iNumber = cast[int64](iNumber)
@@ -581,7 +581,7 @@ proc getNumber(L: var TLexer, result: var TToken) =
         try:
           len = parseBiggestInt(result.literal, iNumber)
         except ValueError:
-          raise newException(OverflowError, "number out of range: " & $result.literal)
+          raise newException(OverflowDefect, "number out of range: " & $result.literal)
         if len != result.literal.len:
           raise newException(ValueError, "invalid integer: " & $result.literal)
         result.iNumber = iNumber
@@ -607,7 +607,7 @@ proc getNumber(L: var TLexer, result: var TToken) =
 
   except ValueError:
     lexMessageLitNum(L, "invalid number: '$1'", startpos)
-  except OverflowError, RangeError:
+  except OverflowDefect, RangeDefect:
     lexMessageLitNum(L, "number out of range: '$1'", startpos)
   tokenEnd(result, postPos-1)
   L.bufpos = postPos

compiler/renderer.nim

@@ -1599,9 +1599,9 @@ proc quoteExpr*(a: string): string {.inline.} =
   ## can be used for quoting expressions in error msgs.
   "'" & a & "'"
 
-proc genFieldError*(field: PSym, disc: PSym): string =
+proc genFieldDefect*(field: PSym, disc: PSym): string =
   ## this needs to be in a module accessible by jsgen, ccgexprs, and vm to
-  ## provide this error msg FieldError; msgs would be better but it does not
+  ## provide this error msg FieldDefect; msgs would be better but it does not
   ## import ast
   result = field.name.s.quoteExpr & " is not accessible using discriminant " &
     disc.name.s.quoteExpr & " of type " &

compiler/semfold.nim

@@ -645,9 +645,9 @@ proc getConstExpr(m: PSym, n: PNode; g: ModuleGraph): PNode =
         discard
       else:
         result = magicCall(m, n, g)
-    except OverflowError:
+    except OverflowDefect:
       localError(g.config, n.info, "over- or underflow")
-    except DivByZeroError:
+    except DivByZeroDefect:
       localError(g.config, n.info, "division by zero")
   of nkAddr:
     var a = getConstExpr(m, n[0], g)

compiler/sempass2.nim

@@ -752,7 +752,7 @@ proc track(tracked: PEffects, n: PNode) =
       createTypeBoundOps(tracked, n[0].typ, n.info)
     else:
       # A `raise` with no arguments means we're going to re-raise the exception
-      # being handled or, if outside of an `except` block, a `ReraiseError`.
+      # being handled or, if outside of an `except` block, a `ReraiseDefect`.
       # Here we add a `Exception` tag in order to cover both the cases.
       addEffect(tracked, createRaise(tracked.graph, n), nil)
   of nkCallKinds: