Make cache CI limit configurable (#18721)

Author: majocha

azure-pipelines-PR.yml

@@ -457,11 +457,13 @@ stages:
                 _configuration: Release
                 _testKind: testFSharpQA
                 transparentCompiler:
+                FSHARP_CACHE_OVERRIDE: 256
               vs_release:
                 _configuration: Release
                 _testKind: testVs
                 setupVsHive: true
                 transparentCompiler:
+                FSHARP_CACHE_OVERRIDE: 256
               transparent_compiler_release:
                 _configuration: Release
                 _testKind: testCoreclr

src/Compiler/Facilities/LanguageFeatures.fs

@@ -224,7 +224,7 @@ type LanguageVersion(versionText) =
 
                 // F# preview
                 LanguageFeature.EnforceAttributeTargets, previewVersion // Not enabled due to a number of external library dependencies on unenforced attributes
-                LanguageFeature.UseTypeSubsumptionCache, previewVersion
+                LanguageFeature.UseTypeSubsumptionCache, languageVersion90
                 LanguageFeature.UnmanagedConstraintCsharpInterop, previewVersion // not enabled because: https://github.com/dotnet/fsharp/issues/17509
                 LanguageFeature.FromEndSlicing, previewVersion // Unfinished features --- needs work
                 LanguageFeature.AllowAccessModifiersToAutoPropertiesGettersAndSetters, previewVersion

src/Compiler/Utilities/Caches.fs

@@ -162,11 +162,11 @@ module Cache =
 
     /// Use for testing purposes to reduce memory consumption in testhost and its subprocesses.
     let OverrideCapacityForTesting () =
-        Environment.SetEnvironmentVariable(overrideVariable, "true", EnvironmentVariableTarget.Process)
+        Environment.SetEnvironmentVariable(overrideVariable, "4096", EnvironmentVariableTarget.Process)
 
     let applyOverride (capacity: int) =
-        match Environment.GetEnvironmentVariable(overrideVariable) with
-        | NonNull _ when capacity > 4096 -> 4096
+        match Int32.TryParse(Environment.GetEnvironmentVariable(overrideVariable)) with
+        | true, n when capacity > n -> n
         | _ -> capacity
 
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