Combining struct field with units of measure will result managed type…

… instead of unmanaged type

fixes dotnet#276
closes dotnet#289

commit 843272178d4369d1fc028ea46956fb669242c212
Author: latkin <latkin@microsoft.com>
Date:   Tue Mar 10 11:19:54 2015 -0700

    Add test covering original bug

commit 4d194c4
Author: andrewjkennedy <akenn@microsoft.com>
Date:   Mon Mar 2 13:13:27 2015 +0000

    Fix for dotnet#276:
    Combining struct field with units of measure will result managed type instead of unmanaged type

    (Regression test to follow)

src/fsharp/csolve.fs

@@ -1740,8 +1740,7 @@ and SolveTypIsUnmanaged (csenv:ConstraintSolverEnv) ndeep m2 trace ty =
     if isTyparTy g ty then 
         AddConstraint csenv ndeep m2 trace (destTyparTy g ty) (TyparConstraint.IsUnmanaged(m))
     else
-        let underlyingTy = stripTyEqnsAndMeasureEqns g ty
-        if isUnmanagedTy g underlyingTy then
+        if isUnmanagedTy g ty then
             CompleteD
         else
             ErrorD (ConstraintSolverError(FSComp.SR.csGenericConstructRequiresUnmanagedType(NicePrint.minimalStringOfType denv ty),m,m2))

src/fsharp/tastops.fs

@@ -1562,6 +1562,7 @@ let isStructTy g ty =
 // - Any non-generic user-defined struct-type that contains fields of unmanaged-types only.
 // [Note: Constructed types and type-parameters are never unmanaged-types. end note]
 let rec isUnmanagedTy g ty =
+    let ty = stripTyEqnsAndMeasureEqns g ty
     if isAppTy g ty then
         let tcref = tcrefOfAppTy g ty
         let isEq tcref2  = tyconRefEq g tcref tcref2 

tests/fsharp/typecheck/sigs/build.bat

@@ -8,6 +8,15 @@ call %~d0%~p0..\..\..\config.bat
 call ..\..\single-neg-test.bat neg91
 @if ERRORLEVEL 1 goto Error
 
+"%FSC%" %fsc_flags% --target:exe -o:pos20.exe  pos20.fs 
+@if ERRORLEVEL 1 goto Error
+
+"%PEVERIFY%" pos20.exe
+@if ERRORLEVEL 1 goto Error
+
+pos20.exe
+@if ERRORLEVEL 1 goto Error
+
 "%FSC%" %fsc_flags% --target:exe -o:pos19.exe  pos19.fs 
 @if ERRORLEVEL 1 goto Error
 

tests/fsharp/typecheck/sigs/pos20.fs

@@ -0,0 +1,16 @@
+// test covering https://github.com/Microsoft/visualfsharp/issues/276
+
+open FSharp.Data.UnitSystems.SI.UnitSymbols 
+
+[<Struct>]
+type S1 =
+  val X: int
+
+[<Struct>]
+type S2 =
+  val X: int<m> 
+
+let f (x : 'T when 'T: unmanaged and 'T: struct) = printfn "%A" x
+
+f (S1())
+f (S2())  // previously had error FS0001: A generic construct requires that the type 'S2' is an unmanaged type