diff options
| -rw-r--r-- | compiler/sem.nim | 23 | ||||
| -rw-r--r-- | compiler/semstmts.nim | 10 | ||||
| -rw-r--r-- | tests/controlflow/tunreachable.nim | 45 |
3 files changed, 64 insertions, 14 deletions
diff --git a/compiler/sem.nim b/compiler/sem.nim index 0dcc66432..2bdb1284f 100644 --- a/compiler/sem.nim +++ b/compiler/sem.nim @@ -210,6 +210,18 @@ proc commonType*(c: PContext; x, y: PType): PType = result = newType(k, c.idgen, r.owner) result.addSonSkipIntLit(r, c.idgen) +const shouldChckCovered = {tyInt..tyInt64, tyChar, tyEnum, tyUInt..tyUInt64, tyBool} +proc shouldCheckCaseCovered(caseTyp: PType): bool = + result = false + case caseTyp.kind + of shouldChckCovered: + result = true + of tyRange: + if skipTypes(caseTyp[0], abstractInst).kind in shouldChckCovered: + result = true + 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 @@ -239,6 +251,12 @@ proc endsInNoReturn(n: PNode): bool = # 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: @@ -248,11 +266,12 @@ proc endsInNoReturn(n: PNode): bool = of nkElifBranch: branch[1] of nkElse: + hasElse = true branch[0] else: raiseAssert "Malformed `case` statement in endsInNoReturn" - # none of the branches returned - result = true + # 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: diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim index 48447c0eb..dcf270a22 100644 --- a/compiler/semstmts.nim +++ b/compiler/semstmts.nim @@ -1146,20 +1146,14 @@ proc semCase(c: PContext, n: PNode; flags: TExprFlags; expectedType: PType = nil openScope(c) pushCaseContext(c, n) n[0] = semExprWithType(c, n[0]) - var chckCovered = false var covered: Int128 = toInt128(0) var typ = commonTypeBegin var expectedType = expectedType var hasElse = false let caseTyp = skipTypes(n[0].typ, abstractVar-{tyTypeDesc}) - const shouldChckCovered = {tyInt..tyInt64, tyChar, tyEnum, tyUInt..tyUInt64, tyBool} + var chckCovered = caseTyp.shouldCheckCaseCovered() case caseTyp.kind - of shouldChckCovered: - chckCovered = true - of tyRange: - if skipTypes(caseTyp[0], abstractInst).kind in shouldChckCovered: - chckCovered = true - of tyFloat..tyFloat128, tyString, tyCstring, tyError: + of tyFloat..tyFloat128, tyString, tyCstring, tyError, shouldChckCovered, tyRange: discard else: popCaseContext(c) diff --git a/tests/controlflow/tunreachable.nim b/tests/controlflow/tunreachable.nim index 64e199e17..06321ce8a 100644 --- a/tests/controlflow/tunreachable.nim +++ b/tests/controlflow/tunreachable.nim @@ -2,9 +2,11 @@ discard """ cmd: "nim check --warningAsError:UnreachableCode $file" action: "reject" nimout: ''' -tunreachable.nim(24, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] -tunreachable.nim(31, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] -tunreachable.nim(40, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] +tunreachable.nim(26, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] +tunreachable.nim(33, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] +tunreachable.nim(42, 3) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] +tunreachable.nim(65, 5) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] +tunreachable.nim(77, 5) Error: unreachable code after 'return' statement or '{.noReturn.}' proc [UnreachableCode] ''' """ @@ -39,4 +41,39 @@ proc main3() = return echo "after" -main3() \ No newline at end of file +main3() + + +block: + # Cases like strings are not checked for exhaustiveness unless they have an else + proc main4(x: string) = + case x + of "a": + return + # reachable + echo "after" + + main4("a") + + proc main5(x: string) = + case x + of "a": + return + else: + return + # unreachable + echo "after" + + main5("a") + +block: + # In this case no else is needed because it's exhaustive + proc exhaustive(x: bool) = + case x + of true: + return + of false: + return + echo "after" + + exhaustive(true) |