diff --git a/compiler/sem.nim b/compiler/sem.nim index a4552beee856f..760b83941d109 100644 --- a/compiler/sem.nim +++ b/compiler/sem.nim @@ -222,66 +222,7 @@ proc shouldCheckCaseCovered(caseTyp: PType): bool = else: discard -proc endsInNoReturn(n: PNode): bool = - ## check if expr ends the block like raising or call of noreturn procs do - result = false # assume it does return - - template checkBranch(branch) = - if not endsInNoReturn(branch): - # proved a branch returns - return false - - var it = n - # skip these beforehand, no special handling needed - while it.kind in {nkStmtList, nkStmtListExpr} and it.len > 0: - it = it.lastSon - - case it.kind - of nkIfStmt: - var hasElse = false - for branch in it: - checkBranch: - if branch.len == 2: - branch[1] - elif branch.len == 1: - hasElse = true - branch[0] - else: - raiseAssert "Malformed `if` statement during endsInNoReturn" - # none of the branches returned - result = hasElse # Only truly a no-return when it's exhaustive - of nkCaseStmt: - let caseTyp = skipTypes(it[0].typ, abstractVar-{tyTypeDesc}) - # semCase should already have checked for exhaustiveness in this case - # effectively the same as having an else - var hasElse = caseTyp.shouldCheckCaseCovered() - - # actual noreturn checks - for i in 1 ..< it.len: - let branch = it[i] - checkBranch: - case branch.kind - of nkOfBranch: - branch[^1] - of nkElifBranch: - branch[1] - of nkElse: - hasElse = true - branch[0] - else: - raiseAssert "Malformed `case` statement in endsInNoReturn" - # Can only guarantee a noreturn if there is an else or it's exhaustive - result = hasElse - of nkTryStmt: - checkBranch(it[0]) - for i in 1 ..< it.len: - let branch = it[i] - checkBranch(branch[^1]) - # none of the branches returned - result = true - else: - result = it.kind in nkLastBlockStmts or - it.kind in nkCallKinds and it[0].kind == nkSym and sfNoReturn in it[0].sym.flags +proc endsInNoReturn(n: PNode): bool proc commonType*(c: PContext; x: PType, y: PNode): PType = # ignore exception raising branches in case/if expressions diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim index a29b07d927c33..8c7dda4e7c2c2 100644 --- a/compiler/semstmts.nim +++ b/compiler/semstmts.nim @@ -132,17 +132,140 @@ proc semExprBranchScope(c: PContext, n: PNode; expectedType: PType = nil): PNode closeScope(c) const - skipForDiscardable = {nkIfStmt, nkIfExpr, nkCaseStmt, nkOfBranch, - nkElse, nkStmtListExpr, nkTryStmt, nkFinally, nkExceptBranch, + skipForDiscardable = {nkStmtList, nkStmtListExpr, + nkOfBranch, nkElse, nkFinally, nkExceptBranch, nkElifBranch, nkElifExpr, nkElseExpr, nkBlockStmt, nkBlockExpr, nkHiddenStdConv, nkHiddenDeref} proc implicitlyDiscardable(n: PNode): bool = - var n = n - while n.kind in skipForDiscardable: n = n.lastSon - result = n.kind in nkLastBlockStmts or - (isCallExpr(n) and n[0].kind == nkSym and - sfDiscardable in n[0].sym.flags) + # same traversal as endsInNoReturn + template checkBranch(branch) = + if not implicitlyDiscardable(branch): + return false + + var it = n + # skip these beforehand, no special handling needed + while it.kind in skipForDiscardable and it.len > 0: + it = it.lastSon + + case it.kind + of nkIfExpr, nkIfStmt: + for branch in it: + checkBranch: + if branch.len == 2: + branch[1] + elif branch.len == 1: + branch[0] + else: + raiseAssert "Malformed `if` statement during implicitlyDiscardable" + # all branches are discardable + result = true + of nkCaseStmt: + for i in 1 ..< it.len: + let branch = it[i] + checkBranch: + case branch.kind + of nkOfBranch: + branch[^1] + of nkElifBranch: + branch[1] + of nkElse: + branch[0] + else: + raiseAssert "Malformed `case` statement in endsInNoReturn" + # all branches are discardable + result = true + of nkTryStmt: + checkBranch(it[0]) + for i in 1 ..< it.len: + let branch = it[i] + if branch.kind != nkFinally: + checkBranch(branch[^1]) + # all branches are discardable + result = true + of nkCallKinds: + result = it[0].kind == nkSym and {sfDiscardable, sfNoReturn} * it[0].sym.flags != {} + of nkLastBlockStmts: + result = true + else: + result = false + +proc endsInNoReturn(n: PNode, returningNode: var PNode): bool = + ## check if expr ends the block like raising or call of noreturn procs do + result = false # assume it does return + + template checkBranch(branch) = + if not endsInNoReturn(branch, returningNode): + # proved a branch returns + return false + + var it = n + # skip these beforehand, no special handling needed + while it.kind in skipForDiscardable and it.len > 0: + it = it.lastSon + + case it.kind + of nkIfExpr, nkIfStmt: + var hasElse = false + for branch in it: + checkBranch: + if branch.len == 2: + branch[1] + elif branch.len == 1: + hasElse = true + branch[0] + else: + raiseAssert "Malformed `if` statement during endsInNoReturn" + # none of the branches returned + result = hasElse # Only truly a no-return when it's exhaustive + of nkCaseStmt: + let caseTyp = skipTypes(it[0].typ, abstractVar-{tyTypeDesc}) + # semCase should already have checked for exhaustiveness in this case + # effectively the same as having an else + var hasElse = caseTyp.shouldCheckCaseCovered() + + # actual noreturn checks + for i in 1 ..< it.len: + let branch = it[i] + checkBranch: + case branch.kind + of nkOfBranch: + branch[^1] + of nkElifBranch: + branch[1] + of nkElse: + hasElse = true + branch[0] + else: + raiseAssert "Malformed `case` statement in endsInNoReturn" + # Can only guarantee a noreturn if there is an else or it's exhaustive + result = hasElse + of nkTryStmt: + checkBranch(it[0]) + var lastIndex = it.len - 1 + if it[lastIndex].kind == nkFinally: + # if finally is noreturn, then the entire statement is noreturn + if endsInNoReturn(it[lastIndex][^1], returningNode): + return true + dec lastIndex + for i in 1 .. lastIndex: + let branch = it[i] + checkBranch(branch[^1]) + # none of the branches returned + result = true + of nkLastBlockStmts: + result = true + of nkCallKinds: + result = it[0].kind == nkSym and sfNoReturn in it[0].sym.flags + if not result: + returningNode = it + else: + result = false + returningNode = it + +proc endsInNoReturn(n: PNode): bool = + var dummy: PNode = nil + result = endsInNoReturn(n, dummy) proc fixNilType(c: PContext; n: PNode) = if isAtom(n): @@ -165,13 +288,9 @@ proc discardCheck(c: PContext, result: PNode, flags: TExprFlags) = localError(c.config, result.info, "expression has no type: " & renderTree(result, {renderNoComments})) else: - var n = result - while n.kind in skipForDiscardable: - if n.kind == nkTryStmt: n = n[0] - else: n = n.lastSon - # Ignore noreturn procs since they don't have a type - if n.endsInNoReturn: + var n = result + if result.endsInNoReturn(n): return var s = "expression '" & $n & "' is of type '" & diff --git a/lib/std/syncio.nim b/lib/std/syncio.nim index 2b39375eaf00a..c34a025af5c86 100644 --- a/lib/std/syncio.nim +++ b/lib/std/syncio.nim @@ -874,7 +874,7 @@ proc writeFile*(filename: string, content: openArray[byte]) {.since: (1, 1).} = var f: File = nil if open(f, filename, fmWrite): try: - f.writeBuffer(unsafeAddr content[0], content.len) + discard f.writeBuffer(unsafeAddr content[0], content.len) finally: close(f) else: diff --git a/tests/discard/t23677.nim b/tests/discard/t23677.nim new file mode 100644 index 0000000000000..1ed7386bde20e --- /dev/null +++ b/tests/discard/t23677.nim @@ -0,0 +1,12 @@ +discard """ + errormsg: "expression '0' is of type 'int literal(0)' and has to be used (or discarded); start of expression here: t23677.nim(1, 1)" + line: 10 + column: 3 +""" + +# issue #23677 + +if true: + 0 +else: + raise newException(ValueError, "err") diff --git a/tests/discard/tdiscardable.nim b/tests/discard/tdiscardable.nim index 69cb9f6a195f9..5988f59497d13 100644 --- a/tests/discard/tdiscardable.nim +++ b/tests/discard/tdiscardable.nim @@ -5,6 +5,7 @@ tdiscardable 1 something defered something defered +hi ''' """ @@ -110,3 +111,32 @@ block: doAssertRaises(ValueError): doAssert foo() == 12 + +block: # issue #10440 + proc x(): int {.discardable.} = discard + try: + x() + finally: + echo "hi" + +import macros + +block: # issue #14665 + macro test(): untyped = + let b = @[1, 2, 3, 4] + + result = nnkStmtList.newTree() + var i = 0 + while i < b.len: + if false: + # this quote do is mandatory, removing it fixes the problem + result.add quote do: + let testtest = 5 + else: + result.add quote do: + let test = 6 + inc i + # removing this continue fixes the problem too + continue + inc i + test() diff --git a/tests/discard/tfinallyerrmsg.nim b/tests/discard/tfinallyerrmsg.nim new file mode 100644 index 0000000000000..fbc8140aaf29a --- /dev/null +++ b/tests/discard/tfinallyerrmsg.nim @@ -0,0 +1,19 @@ +discard """ + cmd: "nim check $file" +""" + +block: # issue #19672 + try: + 10 #[tt.Error + ^ expression '10' is of type 'int literal(10)' and has to be used (or discarded); start of expression here: tfinallyerrmsg.nim(5, 1)]# + finally: + echo "Finally block" + +block: # issue #13871 + template t(body: int) = + try: + body + finally: + echo "expression" + t: 2 #[tt.Error + ^ expression '2' is of type 'int literal(2)' and has to be used (or discarded)]#