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catchable defects (#13626)

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* allow defects to be caught even for --exceptions:goto (WIP)
* implemented the new --panics:on|off switch; refs https://github.com/nim-lang/RFCs/issues/180
* new implementation for integer overflow checking
* produce a warning if a user-defined exception type inherits from Exception directly
* applied Timothee's suggestions; improved the documentation and replace the term 'checked runtime check' by 'panic'
* fixes #13627
* don't inherit from Exception directly
This commit is contained in:
Andreas Rumpf 2020-03-12 23:44:33 +01:00 • committed by GitHub
commit a6682de004
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35 changed files with 441 additions and 142 deletions
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63
compiler/ccgstmts.nim
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@ -706,6 +706,22 @@ proc finallyActions(p: BProc) =
if finallyBlock != nil:
genSimpleBlock(p, finallyBlock[0])
proc raiseInstr(p: BProc): Rope =
if p.config.exc == excGoto:
let L = p.nestedTryStmts.len
if L == 0:
p.flags.incl beforeRetNeeded
# easy case, simply goto 'ret':
result = ropecg(p.module, "goto BeforeRet_;$n", [])
else:
# raise inside an 'except' must go to the finally block,
# raise outside an 'except' block must go to the 'except' list.
result = ropecg(p.module, "goto LA$1_;$n",
[p.nestedTryStmts[L-1].label])
# + ord(p.nestedTryStmts[L-1].inExcept)])
else:
result = nil
proc genRaiseStmt(p: BProc, t: PNode) =
if p.config.exc == excCpp:
discard cgsym(p.module, "popCurrentExceptionEx")
@ -733,18 +749,9 @@ proc genRaiseStmt(p: BProc, t: PNode) =
line(p, cpsStmts, ~"throw;$n")
else:
linefmt(p, cpsStmts, "#reraiseException();$n", [])
if p.config.exc == excGoto:
let L = p.nestedTryStmts.len
if L == 0:
p.flags.incl beforeRetNeeded
# easy case, simply goto 'ret':
lineCg(p, cpsStmts, "goto BeforeRet_;$n", [])
else:
# raise inside an 'except' must go to the finally block,
# raise outside an 'except' block must go to the 'except' list.
lineCg(p, cpsStmts, "goto LA$1_;$n",
[p.nestedTryStmts[L-1].label])
# + ord(p.nestedTryStmts[L-1].inExcept)])
let gotoInstr = raiseInstr(p)
if gotoInstr != nil:
line(p, cpsStmts, gotoInstr)
template genCaseGenericBranch(p: BProc, b: PNode, e: TLoc,
rangeFormat, eqFormat: FormatStr, labl: TLabel) =
@ -1009,14 +1016,14 @@ proc genTryCpp(p: BProc, t: PNode, d: var TLoc) =
genSimpleBlock(p, t[^1][0])
proc bodyCanRaise(n: PNode): bool =
proc bodyCanRaise(p: BProc; n: PNode): bool =
case n.kind
of nkCallKinds:
result = canRaise(n[0])
result = canRaiseDisp(p, n[0])
if not result:
# also check the arguments:
for i in 1 ..< n.len:
if bodyCanRaise(n[i]): return true
if bodyCanRaise(p, n[i]): return true
of nkRaiseStmt:
result = true
of nkTypeSection, nkProcDef, nkConverterDef, nkMethodDef, nkIteratorDef,
@ -1024,22 +1031,24 @@ proc bodyCanRaise(n: PNode): bool =
result = false
else:
for i in 0 ..< safeLen(n):
if bodyCanRaise(n[i]): return true
if bodyCanRaise(p, n[i]): return true
result = false
proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
if not bodyCanRaise(t):
let fin = if t[^1].kind == nkFinally: t[^1] else: nil
inc p.labels
let lab = p.labels
p.nestedTryStmts.add((fin, false, Natural lab))
if not bodyCanRaise(p, t):
# optimize away the 'try' block:
expr(p, t[0], d)
if t.len > 1 and t[^1].kind == nkFinally:
genStmts(p, t[^1][0])
linefmt(p, cpsStmts, "LA$1_: ;$n", [lab])
if fin != nil:
genStmts(p, fin[0])
discard pop(p.nestedTryStmts)
return
let fin = if t[^1].kind == nkFinally: t[^1] else: nil
inc p.labels, 2
let lab = p.labels-1
p.nestedTryStmts.add((fin, false, Natural lab))
p.flags.incl nimErrorFlagAccessed
p.procSec(cpsLocals).add(ropecg(p.module, "NI oldNimErr$1_;$n", [lab]))
linefmt(p, cpsStmts, "oldNimErr$1_ = *nimErr_; *nimErr_ = 0;;$n", [lab])
@ -1099,7 +1108,7 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
#linefmt(p, cpsStmts, "LA$1_:;$n", [lab+1])
if i < t.len and t[i].kind == nkFinally:
startBlock(p)
if not bodyCanRaise(t[i][0]):
if not bodyCanRaise(p, t[i][0]):
# this is an important optimization; most destroy blocks are detected not to raise an
# exception and so we help the C optimizer by not mutating nimErr_ pointlessly:
genStmts(p, t[i][0])
@ -1380,8 +1389,8 @@ proc asgnFieldDiscriminant(p: BProc, e: PNode) =
genCaseObjDiscMapping(p, e[0], t, field, oldVal)
genCaseObjDiscMapping(p, e[1], t, field, newVal)
lineCg(p, cpsStmts,
"#nimFieldDiscriminantCheckV2($1, $2);$n",
[rdLoc(oldVal), rdLoc(newVal)])
"if ($1 != $2) { #raiseObjectCaseTransition(); $3}$n",
[rdLoc(oldVal), rdLoc(newVal), raiseInstr(p)])
else:
genDiscriminantCheck(p, a, tmp, dotExpr[0].typ, field)
genAssignment(p, a, tmp, {})