Report floating streams (#711)

Author: mattiamanzati

.changeset/calm-hounds-tease.md

@@ -0,0 +1,5 @@
+---
+"@effect/language-service": patch
+---
+
+Report floating `Stream` values in Effect projects by parsing `Stream` types in the diagnostic type parser and checking them in `floatingEffect` for both v3 and v4 harnesses.

packages/harness-effect-v4/__snapshots__/diagnostics/floatingEffect_stream.ts.codefixes

@@ -1 +1,2 @@
-no codefixes
+floatingEffect_skipNextLine from 134 to 152
+floatingEffect_skipFile from 134 to 152

packages/harness-effect-v4/__snapshots__/diagnostics/floatingEffect_stream.ts.output

@@ -1 +1,2 @@
-// no diagnostics
+Stream.succeed(42)
+5:2 - 5:20 | 1 | Effect-able Stream<number, never, never> must be yielded or assigned to a variable.    effect(floatingEffect)

packages/language-service/src/core/TypeParser.ts

@@ -60,6 +60,10 @@ export interface TypeParser {
     type: ts.Type,
     atLocation: ts.Node
   ) => Nano.Nano<{ A: ts.Type; E: ts.Type; R: ts.Type }, TypeParserIssue>
+  streamType: (
+    type: ts.Type,
+    atLocation: ts.Node
+  ) => Nano.Nano<{ A: ts.Type; E: ts.Type; R: ts.Type }, TypeParserIssue>
   strictEffectType: (
     type: ts.Type,
     atLocation: ts.Node
@@ -764,6 +768,19 @@ export function make(
       ([A, E, R]) => ({ A, E, R })
     )
 
+  const streamVarianceStruct = (
+    type: ts.Type,
+    atLocation: ts.Node
+  ) =>
+    Nano.map(
+      Nano.all(
+        varianceStructCovariantType(type, atLocation, "_A"),
+        varianceStructCovariantType(type, atLocation, "_E"),
+        varianceStructCovariantType(type, atLocation, "_R")
+      ),
+      ([A, E, R]) => ({ A, E, R })
+    )
+
   const layerVarianceStruct = (
     type: ts.Type,
     atLocation: ts.Node
@@ -830,6 +847,27 @@ export function make(
     (type) => type
   )
 
+  const streamType = Nano.cachedBy(
+    Nano.fn("TypeParser.streamType")(function*(
+      type: ts.Type,
+      atLocation: ts.Node
+    ) {
+      if (supportedEffect() === "v3") {
+        return yield* effectType(type, atLocation)
+      }
+
+      const typeIdSymbol = typeChecker.getPropertyOfType(type, "~effect/Stream")
+      if (!typeIdSymbol) {
+        return yield* typeParserIssue("Type is not a stream", type, atLocation)
+      }
+
+      const typeIdType = typeChecker.getTypeOfSymbolAtLocation(typeIdSymbol, atLocation)
+      return yield* streamVarianceStruct(typeIdType, atLocation)
+    }),
+    "TypeParser.streamType",
+    (type) => type
+  )
+
   const isEffectTypeSourceFile = Nano.cachedBy(
     Nano.fn("TypeParser.isEffectTypeSourceFile")(function*(
       sourceFile: ts.SourceFile
@@ -3124,6 +3162,7 @@ export function make(
     isServiceMapTypeSourceFile,
     isNodeReferenceToServiceMapModuleApi,
     effectType,
+    streamType,
     strictEffectType,
     layerType,
     fiberType,

packages/language-service/src/diagnostics/floatingEffect.ts

@@ -55,7 +55,12 @@ export const floatingEffect = LSP.createDiagnostic({
       const type = typeCheckerUtils.getTypeAtLocation(node.expression)
       if (!type) continue
       // if type is an effect
-      const effect = yield* Nano.option(typeParser.effectType(type, node.expression))
+      const effect = yield* Nano.option(
+        pipe(
+          typeParser.effectType(type, node.expression),
+          Nano.orElse(() => typeParser.streamType(type, node.expression))
+        )
+      )
       if (Option.isSome(effect)) {
         // and not a fiber (we consider that a valid operation)
         const allowedFloatingEffects = yield* pipe(