From c57da0cf5945cfb45eed06f1fd820435cda3ee3a Mon Sep 17 00:00:00 2001
From: Walter Bright <WalterBright@users.noreply.github.com>
Date: Tue, 31 Dec 2024 01:00:03 -0800
Subject: [PATCH] fix #20621 Comparing addresses of rvalue reference parameters
 not correct (#20622)

---
 compiler/src/dmd/backend/inliner.d | 15 ++++++++++++++-
 compiler/src/dmd/constfold.d       | 13 ++++++++++++-
 compiler/src/dmd/e2ir.d            | 10 ++++++++++
 compiler/test/runnable/rvalue1.d   |  2 ++
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/compiler/src/dmd/backend/inliner.d b/compiler/src/dmd/backend/inliner.d
index cf24050e4b3b..e4bac8fa56f6 100644
--- a/compiler/src/dmd/backend/inliner.d
+++ b/compiler/src/dmd/backend/inliner.d
@@ -516,7 +516,20 @@ private elem* initializeParamsWithArgs(elem* eargs, SYMIDX sistart, SYMIDX siend
         {
             if (log) printf("detected slice with %s\n", s.Sident.ptr);
             auto s2 = nextSymbol(si);
-            if (!s2) { symbol_print(*s); elem_print(e); assert(0); }
+            if (!s2)
+            {
+		for (size_t m = args.length; m; --m)
+		{
+		    elem* ex = args[m - 1];
+		    printf("arg[%d]\n", cast(int) m);
+		    elem_print(ex);
+		}
+
+                printf("function: %s\n", funcsym_p.Sident.ptr);
+		printf("szs: %d sze: %d\n", cast(int)szs, cast(int)sze);
+                printf("detected slice with %s\n", s.Sident.ptr);
+                symbol_print(*s); elem_print(e); assert(0);
+            }
             assert(szs == type_size(s2.Stype));
             const ty = s.Stype.Tty;
 
diff --git a/compiler/src/dmd/constfold.d b/compiler/src/dmd/constfold.d
index 1578ef770a09..9d5aa96416b5 100644
--- a/compiler/src/dmd/constfold.d
+++ b/compiler/src/dmd/constfold.d
@@ -806,6 +806,7 @@ UnionExp Equal(EXP op, const ref Loc loc, Type type, Expression e1, Expression e
 
 UnionExp Identity(EXP op, const ref Loc loc, Type type, Expression e1, Expression e2)
 {
+    //printf("Identity %s %s\n", e1.toChars(), e2.toChars());
     UnionExp ue = void;
     int cmp;
     if (e1.op == EXP.null_)
@@ -820,7 +821,17 @@ UnionExp Identity(EXP op, const ref Loc loc, Type type, Expression e1, Expressio
     {
         SymOffExp es1 = e1.isSymOffExp();
         SymOffExp es2 = e2.isSymOffExp();
-        cmp = (es1.var == es2.var && es1.offset == es2.offset);
+        cmp = es1.offset == es2.offset;
+        if (cmp)
+        {
+            cmp = es1.var == es2.var;
+            if (!cmp && (es1.var.isParameter() || es2.var.isParameter()))
+            {
+                // because of ref's, they may still be the same, we cannot tell
+                cantExp(ue);
+                return ue;
+            }
+        }
     }
     else
     {
diff --git a/compiler/src/dmd/e2ir.d b/compiler/src/dmd/e2ir.d
index e120df28d3a7..e2a2ad09a3ad 100644
--- a/compiler/src/dmd/e2ir.d
+++ b/compiler/src/dmd/e2ir.d
@@ -113,6 +113,11 @@ bool ISX64REF(Declaration var)
                 || (var.storage_class & STC.lazy_)
                 || (var.type.isTypeStruct() && var.type.isTypeStruct().sym.hasCopyConstruction());
         }
+        else if (target.os & Target.OS.Windows)
+        {
+            auto ts = var.type.isTypeStruct();
+            return !(var.storage_class & STC.lazy_) && ts && ts.sym.hasMoveCtor && ts.sym.hasCopyCtor;
+        }
         else if (target.os & Target.OS.Posix)
         {
             return !(var.storage_class & STC.lazy_) && var.type.isTypeStruct() && !var.type.isTypeStruct().sym.isPOD();
@@ -131,6 +136,11 @@ bool ISX64REF(ref IRState irs, Expression exp)
         return exp.type.size(Loc.initial) > registerSize
                || (exp.type.isTypeStruct() && exp.type.isTypeStruct().sym.hasCopyConstruction());
     }
+    else if (irs.target.os & Target.OS.Windows)
+    {
+        auto ts = exp.type.isTypeStruct();
+        return ts && ts.sym.hasMoveCtor && ts.sym.hasCopyCtor;
+    }
     else if (irs.target.os & Target.OS.Posix)
     {
         return exp.type.isTypeStruct() && !exp.type.isTypeStruct().sym.isPOD();
diff --git a/compiler/test/runnable/rvalue1.d b/compiler/test/runnable/rvalue1.d
index 07ea4270b881..f8134f718a9f 100644
--- a/compiler/test/runnable/rvalue1.d
+++ b/compiler/test/runnable/rvalue1.d
@@ -55,6 +55,8 @@ struct S4
 {
     void* p;
 
+    this(ref S4) { }
+
     this(S4 s)
     {
         assert(&s is &x); // confirm the rvalue reference