fix #8242, fix #12586: fix 'formatFloat' with 'precision = 0' (#12592)

* fix #8242, fix #12586: fix 'formatFloat' with 'precision = 0'

'formatFloat' with 'precision = 0' now gives the same result
(a number without a decimal point) in all backends.
This is compatible with Python's formatters, too.

* fix failing tests

* add changelog entry

* add version switch

changelog.md

@@ -7,29 +7,47 @@
 
 ### Breaking changes in the standard library
 
-- `base64.encode` no longer supports `lineLen` and `newLine` use `base64.encodeMIME` instead.
-- `os.splitPath()` behavior synchronized with `os.splitFile()` to return "/" as the dir component of "/root_sub_dir" instead of the empty string.
-- `sequtils.zip` now returns a sequence of anonymous tuples i.e. those tuples now do not have fields named "a" and "b".
+- `base64.encode` no longer supports `lineLen` and `newLine`.
+  Use `base64.encodeMIME` instead.
+- `os.splitPath()` behavior synchronized with `os.splitFile()` to return "/"
+   as the dir component of "/root_sub_dir" instead of the empty string.
+- `sequtils.zip` now returns a sequence of anonymous tuples i.e. those tuples
+  now do not have fields named "a" and "b".
+- `strutils.formatFloat` with `precision = 0` has the same behavior in all
+  backends, and it is compatible with Python's behavior,
+  e.g. `formatFloat(3.14159, precision = 0)` is now `3`, not `3.`.
+
 
 ### Breaking changes in the compiler
 
-- Implicit conversions for `const` behave correctly now, meaning that code like `const SOMECONST = 0.int; procThatTakesInt32(SOMECONST)` will be illegal now.
+- Implicit conversions for `const` behave correctly now, meaning that code like
+  `const SOMECONST = 0.int; procThatTakesInt32(SOMECONST)` will be illegal now.
   Simply write `const SOMECONST = 0` instead.
 
 
+
 ## Library additions
 
 - `macros.newLit` now works for ref object types.
 - `system.writeFile` has been overloaded to also support `openarray[byte]`.
-- Added overloaded `strformat.fmt` macro that use specified characters as delimiter instead of '{' and '}'.
+- Added overloaded `strformat.fmt` macro that use specified characters as
+  delimiter instead of '{' and '}'.
+
+
 
 ## Library changes
 
-- `asyncdispatch.drain` now properly takes into account `selector.hasPendingOperations` and only returns once all pending async operations are guaranteed to have completed.
-- `asyncdispatch.drain` now consistently uses the passed timeout value for all iterations of the event loop, and not just the first iteration. This is more consistent with the other asyncdispatch apis, and allows `asyncdispatch.drain` to be more efficient.
+- `asyncdispatch.drain` now properly takes into account `selector.hasPendingOperations`
+  and only returns once all pending async operations are guaranteed to have completed.
+- `asyncdispatch.drain` now consistently uses the passed timeout value for all
+  iterations of the event loop, and not just the first iteration.
+  This is more consistent with the other asyncdispatch apis, and allows
+  `asyncdispatch.drain` to be more efficient.
 - `base64.encode` and `base64.decode` was made faster by about 50%.
 - `htmlgen` adds [MathML](https://wikipedia.org/wiki/MathML) support (ISO 40314).
 
+
+
 ## Language additions
 
 
@@ -45,9 +63,12 @@
 
 ### Compiler changes
 
-- JS target indent is all spaces, instead of mixed spaces and tabs, for generated JavaScript.
+- JS target indent is all spaces, instead of mixed spaces and tabs, for
+  generated JavaScript.
+
 
 
 ## Bugfixes
 
-- The `FD` variant of `selector.unregister` for `ioselector_epoll` and `ioselector_select` now properly handle the `Event.User` select event type.
+- The `FD` variant of `selector.unregister` for `ioselector_epoll` and
+  `ioselector_select` now properly handle the `Event.User` select event type.

lib/pure/strformat.nim

@@ -692,12 +692,11 @@ when isMainModule:
   check &"{-123.456:.3f}", "-123.456"
   check &"{123.456:1g}", "123.456"
   check &"{123.456:.1f}", "123.5"
-  check &"{123.456:.0f}", "123."
-  #check &"{123.456:.0f}", "123."
+  check &"{123.456:.0f}", "123"
   check &"{123.456:>9.3f}", "  123.456"
   check &"{123.456:9.3f}", "  123.456"
   check &"{123.456:>9.4f}", " 123.4560"
-  check &"{123.456:>9.0f}", "     123."
+  check &"{123.456:>9.0f}", "      123"
   check &"{123.456:<9.4f}", "123.4560 "
 
   # Float (scientific) tests

lib/pure/strutils.nim

@@ -2338,7 +2338,7 @@ proc formatBiggestFloat*(f: BiggestFloat, format: FloatFormatMode = ffDefault,
     for i in 0 ..< result.len:
       # Depending on the locale either dot or comma is produced,
       # but nothing else is possible:
-      if result[i] in {'.', ','}: result[i] = decimalsep
+      if result[i] in {'.', ','}: result[i] = decimalSep
   else:
     const floatFormatToChar: array[FloatFormatMode, char] = ['g', 'f', 'e']
     var
@@ -2369,6 +2369,10 @@ proc formatBiggestFloat*(f: BiggestFloat, format: FloatFormatMode = ffDefault,
       # but nothing else is possible:
       if buf[i] in {'.', ','}: result[i] = decimalSep
       else: result[i] = buf[i]
+    when (NimMajor, NimMinor) >= (1, 1):
+      # remove trailing dot, compatible with Python's formatter and JS backend
+      if result[^1] == decimalSep:
+        result.setLen(len(result)-1)
     when defined(windows):
       # VS pre 2015 violates the C standard: "The exponent always contains at
       # least two digits, and only as many more digits as necessary to
@@ -3135,8 +3139,7 @@ proc wordWrap*(s: string, maxLineWidth = 80,
 when isMainModule:
   proc nonStaticTests =
     doAssert formatBiggestFloat(1234.567, ffDecimal, -1) == "1234.567000"
-    when not defined(js):
-      doAssert formatBiggestFloat(1234.567, ffDecimal, 0) == "1235." # <=== bug 8242
+    doAssert formatBiggestFloat(1234.567, ffDecimal, 0) == "1235" # bugs 8242, 12586
     doAssert formatBiggestFloat(1234.567, ffDecimal, 1) == "1234.6"
     doAssert formatBiggestFloat(0.00000000001, ffDecimal, 11) == "0.00000000001"
     doAssert formatBiggestFloat(0.00000000001, ffScientific, 1, ',') in
@@ -3201,17 +3204,6 @@ when isMainModule:
     doAssert alignLeft("1232", 6) == "1232  "
     doAssert alignLeft("1232", 6, '#') == "1232##"
 
-    let
-      inp = """ this is a long text --  muchlongerthan10chars and here
-                 it goes"""
-      outp = " this is a\nlong text\n--\nmuchlongerthan10chars\nand here\nit goes"
-    doAssert wordWrap(inp, 10, false) == outp
-
-    let
-      longInp = """ThisIsOneVeryLongStringWhichWeWillSplitIntoEightSeparatePartsNow"""
-      longOutp = "ThisIsOn\neVeryLon\ngStringW\nhichWeWi\nllSplitI\nntoEight\nSeparate\nPartsNow"
-    doAssert wordWrap(longInp, 8, true) == longOutp
-
     doAssert "$animal eats $food." % ["animal", "The cat", "food", "fish"] ==
              "The cat eats fish."
 

tests/destructor/tnewruntime_strutils.nim

@@ -14,8 +14,7 @@ proc retTuple(): (seq[int], int) =
 
 proc nonStaticTests =
   doAssert formatBiggestFloat(1234.567, ffDecimal, -1) == "1234.567000"
-  when not defined(js):
-    doAssert formatBiggestFloat(1234.567, ffDecimal, 0) == "1235."           # <=== bug 8242
+  doAssert formatBiggestFloat(1234.567, ffDecimal, 0) == "1235" # bugs 8242, 12586
   doAssert formatBiggestFloat(1234.567, ffDecimal, 1) == "1234.6"
   doAssert formatBiggestFloat(0.00000000001, ffDecimal, 11) == "0.00000000001"
   doAssert formatBiggestFloat(0.00000000001, ffScientific, 1, ',') in