[GHC] #9854: Literal overflow check is too aggressive
#9854: Literal overflow check is too aggressive -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The literal overflow check is too aggressive. Sometimes you want to give a literal as a hexadecimal value that does fit inside e.g. an `Int`, like so: {{{ Prelude> 0xdc36d1615b7400a4 :: Int <interactive>:2:1: Warning: Literal 15868100553162883236 is out of the Int range -9223372036854775808..9223372036854775807 -2578643520546668380 }}} However the compiler complains because of the wrap-around. I feel this is common enough and practice (and perfectly well-defined) that the compiler shouldn't warn. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9854 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9854: Literal overflow check is too aggressive -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by tibbe): According to @hvr gcc allows this kind of signed/unsigned overflow with -Woverflow. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9854#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9854: Literal overflow check is too aggressive -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: Incorrect | Blocked By: warning at compile-time | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by thomie): * failure: None/Unknown => Incorrect warning at compile-time Comment: For reference: `-fwarn-overflowed-literals` was added in #7895. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9854#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#9854: Literal overflow check is too aggressive -------------------------------------+------------------------------------- Reporter: tibbe | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by nh2): * cc: nh2 (added) Comment: I think we should always warn on literal integer overflow, and disabled only by explicit programmer annotation, not matter if it's common practice or not. Hex or not, you may just have misremembered what the range of your value is. Rust is also pushing people away from such common practice overflows into the, in my opinion very positive, direction of always warning on possible programmer errors and demanding explicit annotations. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9854#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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