Don't warn about FSharp.Core redirects for projects that inherit their framework

RELEASE_NOTES.md

@@ -2,6 +2,7 @@
 
 * `paket pack --symbols` no longer fails on a project with Compile entries without an `Include` or `Update` attribute, such as `<Compile Remove="..." />` or a Compile item definition in an `ItemDefinitionGroup`, and leaves out of the symbols package the files that a Remove names without wildcards - https://github.com/fsprojects/Paket/issues/4222
 * `paket update --no-install` no longer fails when a group has `generate_load_scripts: true` and the packages of the new paket.lock aren't all restored, as on a fresh checkout or for a package that the update adds: it leaves the load scripts to the next restore, which downloads the packages that they load - https://github.com/fsprojects/Paket/issues/2785
+* `paket install` no longer warns about missing "redirects: force" for FSharp.Core in SDK projects that take their target framework from Directory.Build.props, by inheriting it or through a property such as `$(DefaultTargetFramework)`. Paket, which doesn't read Directory.Build.props, also stops taking such a property for net10 (.NET Framework 1.0): where it needs the framework of the project, as for `framework: auto-detect` or `paket pack`, it falls back to net40, like for a project without framework - https://github.com/fsprojects/Paket/issues/4485
 
 #### 12.0.0-alpha005 - 2026-11-07
 

integrationtests/Paket.IntegrationTests/BindingRedirect.fs

@@ -222,4 +222,19 @@ let ``#1783 generates binding redirect when assembly with different version of m
 
     let config = File.ReadAllText(configPath) |> normalizeLineEndings
 
-    config |> shouldContainText ``Newtonsoft.Json``
+    config |> shouldContainText ``Newtonsoft.Json``
+
+[<Test>]
+let ``#4485 does not warn about FSharp.Core redirects when the framework comes from Directory.Build.props``() =
+    let scenario = "i004485-fsharp-core-warning-inherited-framework"
+    let cleanup, output = paket "install" scenario
+    use __ = cleanup
+    let warnsAbout (project: string) =
+        output.Split('\n')
+        |> Array.exists (fun line -> line.Contains "without specifying \"redirects: force\"" && line.Contains project)
+
+    // the project that declares net48 itself is warned, so that the checks below can't pass
+    // because the text of the warning changed
+    Assert.IsTrue(warnsAbout "Framework.fsproj", output)
+    Assert.IsFalse(warnsAbout "Inherited.fsproj", output)
+    Assert.IsFalse(warnsAbout "Property.fsproj", output)

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/Directory.Build.props

@@ -0,0 +1,6 @@
+<Project>
+  <PropertyGroup>
+    <DefaultTargetFramework>net10.0</DefaultTargetFramework>
+    <TargetFramework>$(DefaultTargetFramework)</TargetFramework>
+  </PropertyGroup>
+</Project>

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/framework/Framework.fsproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net48</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Lib.fs" />
+  </ItemGroup>
+</Project>

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/framework/Lib.fs

@@ -0,0 +1 @@
+module Lib

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/framework/paket.references

@@ -0,0 +1 @@
+FSharp.Core

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/inherited/Inherited.fsproj

@@ -0,0 +1,5 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <Compile Include="Lib.fs" />
+  </ItemGroup>
+</Project>

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/inherited/Lib.fs

@@ -0,0 +1 @@
+module Lib

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/inherited/paket.references

@@ -0,0 +1 @@
+FSharp.Core

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/paket.dependencies

@@ -0,0 +1,4 @@
+source https://api.nuget.org/v3/index.json
+storage: none
+
+nuget FSharp.Core 9.0.303

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/property/Lib.fs

@@ -0,0 +1 @@
+module Lib

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/property/Property.fsproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>$(DefaultTargetFramework)</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Lib.fs" />
+  </ItemGroup>
+</Project>

integrationtests/scenarios/i004485-fsharp-core-warning-inherited-framework/before/property/paket.references

@@ -0,0 +1 @@
+FSharp.Core

src/Paket.Core/Installation/InstallProcess.fs

@@ -343,6 +343,8 @@ let private applyBindingRedirects isFirstGroup createNewBindingFiles cleanBindin
 /// DotNetFramework V5+ but is not .NET Framework) - .NET Core/.NET 5+ and
 /// netstandard-only projects use assembly unification via deps.json instead, so the
 /// warning would be noise there.
+/// The profiles are the ones that the project file declares: without any, as when the
+/// framework comes from Directory.Build.props, Paket can't tell and doesn't warn.
 let shouldWarnAboutFSharpCoreRedirects (targetProfiles: TargetProfile list) (createBindingRedirects: BindingRedirectsSettings option) =
     let targetsDotNetFramework =
         targetProfiles
@@ -519,7 +521,7 @@ let InstallIntoProjects(options : InstallerOptions, forceTouch, dependenciesFile
                     traceWarnfn "F# project %s does not reference FSharp.Core." project.FileName
                 | Some kv ->
                     let _, settings = kv.Value
-                    if shouldWarnAboutFSharpCoreRedirects (project.GetTargetProfiles()) settings.CreateBindingRedirects then
+                    if shouldWarnAboutFSharpCoreRedirects (project.GetDeclaredTargetProfiles()) settings.CreateBindingRedirects then
                         traceWarnfn "F# project %s references FSharp.Core without specifying \"redirects: force\" in paket.dependencies. This can lead to \"Could not load file or assembly 'FSharp.Core'\" errors at runtime. See https://fsprojects.github.io/Paket/dependencies-file.html#Controlling-assembly-binding-redirects for details." project.FileName
 
         // if any errors have been found during the installation process thus far, fail and print all errors collected

src/Paket.Core/PaketConfigFiles/ProjectFile.fs

@@ -1099,7 +1099,10 @@ module ProjectFile =
             | true,  version -> adjustIfWeHaveSDK version
             | _         -> adjustIfWeHaveSDK 4.0
 
-    let getTargetProfiles (project:ProjectFile) =
+    /// The target profiles that the project file declares itself. Paket doesn't read the files that
+    /// it imports, so this is empty when the framework comes from one of them, as from
+    /// Directory.Build.props, or when the file declares no framework that Paket recognizes.
+    let getDeclaredTargetProfiles (project:ProjectFile) =
         let fallback () =
             let prefix() =
                 match getTargetFrameworkIdentifier project with
@@ -1114,9 +1117,12 @@ module ProjectFile =
 
                 | Some x -> [prefix() + (x.Replace("v",""))]
 
-            match frameworks |> List.choose (fun s -> FrameworkDetection.internalExtract s |> Option.map TargetProfile.SinglePlatform) |> List.filter (fun x -> match x with TargetProfile.SinglePlatform(Unsupported _) -> false | _ -> true)  with
-            | [] -> [TargetProfile.SinglePlatform (DotNetFramework FrameworkVersion.V4)]
-            | xs -> xs
+            frameworks
+            // a property defined outside of the project file, as in $(DefaultTargetFramework), expands
+            // to an empty string, which internalExtract would take for .NET Framework 1.0
+            |> List.filter (String.IsNullOrWhiteSpace >> not)
+            |> List.choose (fun s -> FrameworkDetection.internalExtract s |> Option.map TargetProfile.SinglePlatform)
+            |> List.filter (fun x -> match x with TargetProfile.SinglePlatform(Unsupported _) -> false | _ -> true)
 
 
         match getTargetFrameworkProfile project with
@@ -1136,6 +1142,13 @@ module ProjectFile =
                 fallback()
         | _ -> fallback()
 
+    /// The target profiles of the project: the ones that the project file declares, or net40 when
+    /// it declares none (see getDeclaredTargetProfiles).
+    let getTargetProfiles (project:ProjectFile) =
+        match getDeclaredTargetProfiles project with
+        | [] -> [TargetProfile.SinglePlatform (DotNetFramework FrameworkVersion.V4)]
+        | profiles -> profiles
+
     let updateReferences
             (completeModel: Map<GroupName*PackageName,_*InstallModel>)
             (directPackages : Map<GroupName*PackageName,_*InstallSettings>)
@@ -1813,6 +1826,8 @@ type ProjectFile with
 
     member this.GetTargetProfiles() =  ProjectFile.getTargetProfiles this
 
+    member this.GetDeclaredTargetProfiles() =  ProjectFile.getDeclaredTargetProfiles this
+
     member this.AddImportForPaketTargets relativeTargetsPath = ProjectFile.addImportForPaketTargets relativeTargetsPath this
 
     member this.RemoveImportForPaketTargets() =  ProjectFile.removeImportForPaketTargets this

tests/Paket.Tests/ProjectFile/TargetFrameworkSpecs.fs

@@ -48,3 +48,33 @@ let ``should detect the correct framework on test projects`` projectFile expecte
     p.GetTargetProfiles() |> shouldEqual [expectedProfile]
     p.GetTargetProfiles().Head.ToString() |> shouldEqual expectedProfileString
 
+
+let private sdkProject properties =
+    let content =
+        sprintf """<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>%s</PropertyGroup>
+</Project>""" properties
+    ProjectFile.LoadFromString("Project.fsproj", content)
+
+[<Test>]
+let ``declares no target profile when the framework comes from Directory.Build.props`` () =
+    let p = sdkProject ""
+    p.GetDeclaredTargetProfiles() |> shouldEqual []
+    p.GetTargetProfiles() |> shouldEqual [TargetProfile.SinglePlatform(DotNetFramework FrameworkVersion.V4)]
+
+[<Test>]
+let ``declares no target profile when the framework is a property defined outside of the project file`` () =
+    let p = sdkProject "<TargetFramework>$(DefaultTargetFramework)</TargetFramework>"
+    p.GetDeclaredTargetProfiles() |> shouldEqual []
+    p.GetTargetProfiles() |> shouldEqual [TargetProfile.SinglePlatform(DotNetFramework FrameworkVersion.V4)]
+
+[<Test>]
+let ``ignores an empty entry of TargetFrameworks`` () =
+    // the space after the last separator survives the split, and becomes "" once trimmed
+    let p = sdkProject "<TargetFrameworks>net8.0; </TargetFrameworks>"
+    p.GetDeclaredTargetProfiles() |> shouldEqual [TargetProfile.SinglePlatform(DotNetFramework FrameworkVersion.V8)]
+
+[<Test>]
+let ``declares the target profile of the framework in the project file`` () =
+    let p = sdkProject "<TargetFramework>net48</TargetFramework>"
+    p.GetDeclaredTargetProfiles() |> shouldEqual [TargetProfile.SinglePlatform(DotNetFramework FrameworkVersion.V4_8)]