Fix bugzilla 24680 - [dip1000] final auto class method infers scope b…

compiler/src/dmd/declaration.h

@@ -638,12 +638,10 @@ class FuncDeclaration : public Declaration
     bool nothrowInprocess(bool v);
     bool nogcInprocess() const;
     bool nogcInprocess(bool v);
-    bool returnInprocess() const;
-    bool returnInprocess(bool v);
+    bool scopeInprocess() const;
+    bool scopeInprocess(bool v);
     bool inlineScanned() const;
     bool inlineScanned(bool v);
-    bool inferScope() const;
-    bool inferScope(bool v);
     bool hasCatches() const;
     bool hasCatches(bool v);
     bool skipCodegen() const;

compiler/src/dmd/escape.d

@@ -1320,7 +1320,7 @@ private bool checkReturnEscapeImpl(ref Scope sc, Expression e, bool refs, bool g
                 return;
             }
             FuncDeclaration fd = p.isFuncDeclaration();
-            if (fd && sc.func.returnInprocess)
+            if (fd && sc.func.scopeInprocess)
             {
                 /* Code like:
                  *   int x;
@@ -1448,7 +1448,7 @@ private bool inferReturn(FuncDeclaration fd, VarDeclaration v, bool returnScope)
     if (!v.isParameter() || v.isTypesafeVariadicArray || (returnScope && v.doNotInferReturn))
         return false;
 
-    if (!fd.returnInprocess)
+    if (!fd.scopeInprocess)
         return false;
 
     if (returnScope && !(v.isScope() || v.maybeScope))
@@ -2073,24 +2073,20 @@ private void doNotInferScope(VarDeclaration v, RootObject o)
 public
 void finishScopeParamInference(FuncDeclaration funcdecl, ref TypeFunction f)
 {
+    if (!funcdecl.scopeInprocess)
+        return;
+    funcdecl.scopeInprocess = false;
 
-    if (funcdecl.returnInprocess)
+    if (funcdecl.storage_class & STC.return_)
     {
-        funcdecl.returnInprocess = false;
-        if (funcdecl.storage_class & STC.return_)
-        {
-            if (funcdecl.type == f)
-                f = cast(TypeFunction)f.copy();
-            f.isreturn = true;
-            f.isreturnscope = cast(bool) (funcdecl.storage_class & STC.returnScope);
-            if (funcdecl.storage_class & STC.returninferred)
-                f.isreturninferred = true;
-        }
+        if (funcdecl.type == f)
+            f = cast(TypeFunction)f.copy();
+        f.isreturn = true;
+        f.isreturnscope = cast(bool) (funcdecl.storage_class & STC.returnScope);
+        if (funcdecl.storage_class & STC.returninferred)
+            f.isreturninferred = true;
     }
 
-    if (!funcdecl.inferScope)
-        return;
-    funcdecl.inferScope = false;
 
     // Infer STC.scope_
     if (funcdecl.parameters && !funcdecl.errors)

compiler/src/dmd/frontend.h

@@ -3698,12 +3698,10 @@ class FuncDeclaration : public Declaration
     bool nothrowInprocess(bool v);
     bool nogcInprocess() const;
     bool nogcInprocess(bool v);
-    bool returnInprocess() const;
-    bool returnInprocess(bool v);
+    bool scopeInprocess() const;
+    bool scopeInprocess(bool v);
     bool inlineScanned() const;
     bool inlineScanned(bool v);
-    bool inferScope() const;
-    bool inferScope(bool v);
     bool hasCatches() const;
     bool hasCatches(bool v);
     bool skipCodegen() const;

compiler/src/dmd/func.d

@@ -119,9 +119,8 @@ private struct FUNCFLAG
     bool safetyInprocess;    /// working on determining safety
     bool nothrowInprocess;   /// working on determining nothrow
     bool nogcInprocess;      /// working on determining @nogc
-    bool returnInprocess;    /// working on inferring 'return' for parameters
+    bool scopeInprocess;     /// infer `return` and `scope` for parameters
     bool inlineScanned;      /// function has been scanned for inline possibilities
-    bool inferScope;         /// infer 'scope' for parameters
     bool hasCatches;         /// function has try-catch statements
     bool skipCodegen;        /// do not generate code for this function.
     bool printf;             /// is a printf-like function
@@ -722,11 +721,8 @@ extern (C++) class FuncDeclaration : Declaration
         if (!tf.isnogc)
             nogcInprocess = true;
 
-        if (!isVirtual() || this.isIntroducing())
-            returnInprocess = true;
-
         // Initialize for inferring STC.scope_
-        inferScope = true;
+        scopeInprocess = true;
     }
 
     extern (D) final uint saveFlags()
@@ -1674,7 +1670,7 @@ extern (C++) final class FuncLiteralDeclaration : FuncDeclaration
         this.fes = fes;
         // Always infer scope for function literals
         // See https://issues.dlang.org/show_bug.cgi?id=20362
-        this.inferScope = true;
+        this.scopeInprocess = true;
         //printf("FuncLiteralDeclaration() id = '%s', type = '%s'\n", this.ident.toChars(), type.toChars());
     }
 

compiler/test/fail_compilation/test24680.d

@@ -0,0 +1,20 @@
+/**
+REQUIRED_ARGS: -preview=dip1000
+TEST_OUTPUT:
+---
+fail_compilation/test24680.d(19): Error: returning `c.peek(buf[])` escapes a reference to local variable `buf`
+---
+*/
+
+// https://issues.dlang.org/show_bug.cgi?id=24680
+
+class C
+{
+    final auto peek(ubyte[] buf) { return buf; }
+}
+
+@safe escape(C c)
+{
+    ubyte[5] buf;
+    return c.peek(buf[]);
+}