strict effects (#18777)

* fixes #17369
* megatest is green for --cpu:arm64
* docgen output includes more tags/raises
* implemented 'effectsOf' 
* algorithm.nim: uses new effectsOf annotation
* closes #18376
* closes #17475
* closes #13905
* allow effectsOf: [a, b]
* added a test case
* parameters that are not ours cannot be declared as .effectsOf
* documentation
* manual: added the 'sort' example
* bootstrap with the new better options

tests/effects/teffects1.nim

@@ -6,7 +6,7 @@ teffects1.nim(22, 29) Hint: 'lier' cannot raise 'IO2Error' [XCannotRaiseY]
 teffects1.nim(38, 21) Error: type mismatch: got <proc (x: int): string{.noSideEffect, gcsafe, locks: 0.}> but expected 'MyProcType = proc (x: int): string{.closure.}'
 .raise effects differ'''
 """
-
+{.push warningAsError[Effect]: on.}
 type
   TObj {.pure, inheritable.} = object
   TObjB = object of TObj
@@ -41,3 +41,4 @@ type mismatch: got <proc (x: int): string{.noSideEffect, gcsafe, locks: 0.}> but
 
 ]#
 {.pop.}
+{.pop.}

tests/effects/teffects2.nim

@@ -2,7 +2,7 @@ discard """
   errormsg: "can raise an unlisted exception: ref IOError"
   line: 19
 """
-
+{.push warningAsError[Effect]: on.}
 type
   TObj = object {.pure, inheritable.}
   TObjB = object of TObj
@@ -17,3 +17,4 @@ proc lier(): int {.raises: [IOError].} =
 
 proc forw: int =
   raise newException(IOError, "arg")
+{.pop.}

tests/effects/teffects7.nim

@@ -2,7 +2,7 @@ discard """
   errormsg: "can raise an unlisted exception: ref ValueError"
   line: 10
 """
-
+{.push warningAsError[Effect]: on.}
 proc foo() {.raises: [].} =
   try:
     discard
@@ -12,3 +12,5 @@ proc foo() {.raises: [].} =
     discard
 
 foo()
+
+{.pop.}

tests/effects/teffects8.nim

@@ -2,7 +2,7 @@ discard """
   errormsg: "can raise an unlisted exception: Exception"
   line: 10
 """
-
+{.push warningAsError[Effect]: on.}
 proc foo() {.raises: [].} =
   try:
     discard
@@ -10,3 +10,4 @@ proc foo() {.raises: [].} =
     raise
 
 foo()
+{.pop.}

tests/effects/tstrict_effects.nim

@@ -0,0 +1,27 @@
+discard """
+  errormsg: "s1 can raise an unlisted exception: CatchableError"
+  line: 27
+"""
+
+{.push warningAsError[Effect]: on.}
+{.experimental: "strictEffects".}
+
+# bug #18376
+
+{.push raises: [Defect].}
+type Call = proc (x: int): int {.gcsafe, raises: [Defect, CatchableError].}
+
+type Bar* = object
+  foo*: Call
+
+proc passOn*(x: Call) = discard
+
+proc barCal(b: var Bar, s: string, s1: Call) =
+  #compiler complains that his line can throw CatchableError
+  passOn s1
+
+
+proc passOnB*(x: Call) {.effectsOf: x.} = discard
+
+proc barCal2(b: var Bar, s: string, s1: Call) =
+  passOnB s1

tests/effects/tstrict_effects2.nim

@@ -0,0 +1,28 @@
+discard """
+  errormsg: "can raise an unlisted exception: Exception"
+  line: 23
+"""
+
+{.push warningAsError[Effect]: on.}
+{.experimental: "strictEffects".}
+
+# bug #13905
+
+proc atoi(v: cstring): cint {.importc: "atoi", cdecl, raises: [].}
+
+type Conv = proc(v: cstring): cint {.cdecl, raises: [].}
+
+var x: Conv = atoi
+
+# bug #17475
+
+type
+  Callback = proc()
+
+proc f(callback: Callback) {.raises: [].} =
+  callback()
+
+proc main =
+  f(proc () = raise newException(IOError, "IO"))
+
+main()

tests/effects/tstrict_effects3.nim

@@ -0,0 +1,17 @@
+discard """
+  action: compile
+"""
+
+{.push warningAsError[Effect]: on.}
+
+{.experimental: "strictEffects".}
+
+proc fn(a: int, p1, p2: proc()) {.effectsOf: p1.} =
+  if a == 7:
+    p1()
+  if a<0:
+    raise newException(ValueError, $a)
+
+proc main() {.raises: [ValueError].} =
+  fn(1, proc()=discard, proc() = raise newException(IOError, "foo"))
+main()

tests/effects/tstrict_effects_sort.nim

@@ -0,0 +1,27 @@
+discard """
+  errormsg: "cmpE can raise an unlisted exception: Exception"
+  line: 27
+"""
+
+{.push warningAsError[Effect]: on.}
+
+{.experimental: "strictEffects".}
+
+import algorithm
+
+type
+  MyInt = distinct int
+
+var toSort = @[MyInt 1, MyInt 2, MyInt 3]
+
+proc cmpN(a, b: MyInt): int =
+  cmp(a.int, b.int)
+
+proc harmless {.raises: [].} =
+  toSort.sort cmpN
+
+proc cmpE(a, b: MyInt): int {.raises: [Exception].} =
+  cmp(a.int, b.int)
+
+proc harmfull {.raises: [].} =
+  toSort.sort cmpE