make -d:nimFpRoundtrips work consistently in vm vs rt, fix #18400, etc (#18531)

* compiler/vmhooks: add getVar to allow vmops with var params
* addFloat vmops with var param
* cgen now renders float32 literals in c backend using roundtrip float to string

6 files changed, 117 insertions, 42 deletions

diff --git a/tests/config.nims b/tests/config.nims
index 539de5e8d..12b303318 100644
--- a/tests/config.nims
+++ b/tests/config.nims
@@ -34,3 +34,5 @@ hint("Processing", off)
 switch("define", "nimExperimentalAsyncjsThen")
 switch("define", "nimExperimentalJsfetch")
 switch("define", "nimExperimentalLinenoiseExtra")
+
+switch("define", "nimFpRoundtrips")
diff --git a/tests/errmsgs/treportunused.nim b/tests/errmsgs/treportunused.nim
index f9b7c3d11..3105b35ea 100644
--- a/tests/errmsgs/treportunused.nim
+++ b/tests/errmsgs/treportunused.nim
@@ -13,12 +13,12 @@ treportunused.nim(30, 5) Hint: 's8' is declared but not used [XDeclaredButNotUse
 treportunused.nim(31, 5) Hint: 's9' is declared but not used [XDeclaredButNotUsed]
 treportunused.nim(32, 6) Hint: 's10' is declared but not used [XDeclaredButNotUsed]
 treportunused.nim(33, 6) Hint: 's11' is declared but not used [XDeclaredButNotUsed]
+treportunused.nim(37, 3) Hint: 'v0.99' is declared but not used [XDeclaredButNotUsed]
+treportunused.nim(38, 3) Hint: 'v0.99.99' is declared but not used [XDeclaredButNotUsed]
 '''
 action: compile
 """
 
-#treportunused.nim(37, 3) Hint: 'v0.99' is declared but not used [XDeclaredButNotUsed]
-#treportunused.nim(38, 3) Hint: 'v0.99.99' is declared but not used [XDeclaredButNotUsed]
 # bug #9764
 iterator s1(a:string): int = discard
 iterator s2(): int = discard
@@ -32,9 +32,7 @@ var s9: int
 type s10 = object
 type s11 = type(1.2)
 
-when false:
-  # enabled again when Nim bootstraps with -d:nimFpRoundtrips
-  # https://github.com/nim-lang/Nim/issues/14407
-  let
-    `v0.99` = "0.99"
-    `v0.99.99` = "0.99.99"
+# bug #14407 (requires `compiler/nim.cfg` containing define:nimFpRoundtrips)
+let
+  `v0.99` = "0.99"
+  `v0.99.99` = "0.99.99"
diff --git a/tests/float/nim.cfg b/tests/float/nim.cfg
deleted file mode 100644
index d27bbf43b..000000000
--- a/tests/float/nim.cfg
+++ /dev/null
@@ -1 +0,0 @@
--d:nimFpRoundtrips
diff --git a/tests/float/tfloats.nim b/tests/float/tfloats.nim
index 30d9c50d6..63987bb8d 100644
--- a/tests/float/tfloats.nim
+++ b/tests/float/tfloats.nim
@@ -1,13 +1,14 @@
 discard """
+  matrix: "-d:nimFpRoundtrips; -u:nimFpRoundtrips"
   targets: "c cpp js"
 """
-# disabled: "windows"
 
 #[
 xxx merge all or most float tests into this file
 ]#
 
 import std/[fenv, math, strutils]
+import stdtest/testutils
 
 proc equalsOrNaNs(a, b: float): bool =
   if isNaN(a): isNaN(b)
@@ -62,27 +63,103 @@ template main =
     reject "1_.0"
     reject "1.0_"
 
-  block: # bug #18148
-    var a = 1.1'f32
-    doAssert $a == "1.1", $a # was failing
+  block: # bugs mentioned in https://github.com/nim-lang/Nim/pull/18504#issuecomment-881635317
+    block: # example 1
+      let a = 0.1+0.2
+      doAssert a != 0.3
+      when defined(nimFpRoundtrips):
+        doAssert $a == "0.30000000000000004"
+      else:
+        whenRuntimeJs: discard
+        do: doAssert $a == "0.3"
+    block: # example 2
+      const a = 0.1+0.2
+      when defined(nimFpRoundtrips):
+        doAssert $($a, a) == """("0.30000000000000004", 0.30000000000000004)"""
+      else:
+        whenRuntimeJs: discard
+        do: doAssert $($a, a) == """("0.3", 0.3)"""
+    block: # example 3
+      const a1 = 0.1+0.2
+      let a2 = a1
+      doAssert a1 != 0.3
+      when defined(nimFpRoundtrips):
+        doAssert $[$a1, $a2] == """["0.30000000000000004", "0.30000000000000004"]"""
+      else:
+        whenRuntimeJs: discard
+        do: doAssert $[$a1, $a2] == """["0.3", "0.3"]"""
 
-proc runtimeOnlyTests =
-  # enable for 'static' once -d:nimFpRoundtrips became the default
-  block: # bug #7717
-    proc test(f: float) =
-      let f2 = $f
-      let f3 = parseFloat(f2)
-      doAssert equalsOrNaNs(f, f3), $(f, f2, f3)
+  when defined(nimFpRoundtrips):
+    block: # bug #18148
+      var a = 1.1'f32
+      doAssert $a == "1.1", $a # was failing
 
-    test 1.0 + epsilon(float64)
-    test 1000000.0000000123
-    test log2(100000.0)
-    test maximumPositiveValue(float32)
-    test maximumPositiveValue(float64)
-    test minimumPositiveValue(float32)
-    test minimumPositiveValue(float64)
+    block: # bug #18400
+      block:
+        let a1 = 0.1'f32
+        let a2 = 0.2'f32
+        let a3 = a1 + a2
+        var s = ""
+        s.addFloat(a3)
+        whenVMorJs: discard # xxx refs #12884
+        do:
+          doAssert a3 == 0.3'f32
+          doAssert $a3 == "0.3"
+
+      block:
+        let a1 = 0.1
+        let a2 = 0.2
+        let a3 = a1 + a2
+        var s = ""
+        s.addFloat(a3)
+        doAssert a3 != 0.3
+        doAssert $a3 == "0.30000000000000004"
+
+      block:
+        var s = [-13.888888'f32]
+        whenRuntimeJs: discard
+        do:
+          doAssert $s == "[-13.888888]"
+          doAssert $s[0] == "-13.888888"
+
+    block: # bug #7717
+      proc test(f: float) =
+        let f2 = $f
+        let f3 = parseFloat(f2)
+        doAssert equalsOrNaNs(f, f3), $(f, f2, f3)
+      test 1.0 + epsilon(float64)
+      test 1000000.0000000123
+      test log2(100000.0)
+      test maximumPositiveValue(float32)
+      test maximumPositiveValue(float64)
+      test minimumPositiveValue(float32)
+      test minimumPositiveValue(float64)
+
+    block: # bug #12884
+      block: # example 1
+        const x0: float32 = 1.32
+        let x1 = 1.32
+        let x2 = 1.32'f32
+        var x3: float32 = 1.32
+        doAssert $(x0, x1, x2, x3) == "(1.32, 1.32, 1.32, 1.32)"
+      block: # example https://github.com/nim-lang/Nim/issues/12884#issuecomment-564967962
+        let x = float(1.32'f32)
+        when nimvm: discard # xxx prints 1.3
+        else:
+          when not defined(js):
+            doAssert $x == "1.3200000524520874"
+        doAssert $1.32 == "1.32"
+        doAssert $1.32'f32 == "1.32"
+        let x2 = 1.32'f32
+        doAssert $x2 == "1.32"
+      block:
+        var x = 1.23456789012345'f32
+        when nimvm:
+          discard # xxx, refs #12884
+        else:
+          when not defined(js):
+            doAssert x == 1.2345679'f32
+            doAssert $x == "1.2345679"
 
 static: main()
 main()
-
-runtimeOnlyTests()
diff --git a/tests/stdlib/tjson.nim b/tests/stdlib/tjson.nim
index 000f72038..289ef9d05 100644
--- a/tests/stdlib/tjson.nim
+++ b/tests/stdlib/tjson.nim
@@ -303,7 +303,7 @@ let jsonNode = %*mynode
 doAssert $jsonNode == """{"kind":"P","pChildren":[{"kind":"Text","textStr":"mychild"},{"kind":"Br"}]}"""
 doAssert $jsonNode.to(ContentNode) == """(kind: P, pChildren: @[(kind: Text, textStr: "mychild"), (kind: Br)])"""
 
-when defined(nimFpRoundtrips): # bug #17383
+block: # bug #17383
   testRoundtrip(int32.high): "2147483647"
   testRoundtrip(uint32.high): "4294967295"
   when int.sizeof == 4:
@@ -316,7 +316,7 @@ when defined(nimFpRoundtrips): # bug #17383
     testRoundtrip(int64.high): "9223372036854775807"
     testRoundtrip(uint64.high): "18446744073709551615"
 
-when defined(nimFpRoundtrips): # bug #18007
+block: # bug #18007
   testRoundtrip([NaN, Inf, -Inf, 0.0, -0.0, 1.0]): """["nan","inf","-inf",0.0,-0.0,1.0]"""
   # pending https://github.com/nim-lang/Nim/issues/18025 use:
   # testRoundtrip([float32(NaN), Inf, -Inf, 0.0, -0.0, 1.0])
@@ -332,7 +332,7 @@ when defined(nimFpRoundtrips): # bug #18007
     testRoundtripVal(0.0): "0.0"
     testRoundtripVal(-0.0): "-0.0"
 
-when defined(nimFpRoundtrips): # bug #15397, bug #13196
+block: # bug #15397, bug #13196
   testRoundtripVal(1.0 + epsilon(float64)): "1.0000000000000002"
   testRoundtripVal(0.12345678901234567890123456789): "0.12345678901234568"
 
diff --git a/tests/stdlib/tjsonutils.nim b/tests/stdlib/tjsonutils.nim
index 3e9c422e0..205160471 100644
--- a/tests/stdlib/tjsonutils.nim
+++ b/tests/stdlib/tjsonutils.nim
@@ -161,16 +161,15 @@ template fn() =
     doAssert b[2].signbit
     doAssert not b[3].signbit
 
-  when defined(nimFpRoundtrips):
-    block: # bug #15397, bug #13196
-      let a = 0.1
-      let x = 0.12345678901234567890123456789
-      let b = (a + 0.2, 0.3, x)
-      testRoundtripVal(b): "[0.30000000000000004,0.3,0.12345678901234568]"
-
-      testRoundtripVal(0.12345678901234567890123456789): "0.12345678901234568"
-      testRoundtripVal(epsilon(float64)): "2.220446049250313e-16"
-      testRoundtripVal(1.0 + epsilon(float64)): "1.0000000000000002"
+  block: # bug #15397, bug #13196
+    let a = 0.1
+    let x = 0.12345678901234567890123456789
+    let b = (a + 0.2, 0.3, x)
+    testRoundtripVal(b): "[0.30000000000000004,0.3,0.12345678901234568]"
+
+    testRoundtripVal(0.12345678901234567890123456789): "0.12345678901234568"
+    testRoundtripVal(epsilon(float64)): "2.220446049250313e-16"
+    testRoundtripVal(1.0 + epsilon(float64)): "1.0000000000000002"
 
   block: # case object
     type Foo = object