From 5a90fe012b72eb1485ca7ccefa1e817054acf764 Mon Sep 17 00:00:00 2001
From: Ryan McConnell <rammcconnell@gmail.com>
Date: Wed, 17 Sep 2025 11:50:49 -0400
Subject: [PATCH 1/4] fix temp

---
 compiler/sigmatch.nim | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index d3d99a355aa80..01ace6a72fc70 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -1891,6 +1891,21 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
             return isNone
         if doBind: put(c, f, a)
         return isGeneric
+      elif effectiveArgType.kind == tyOr:
+        let oldInheritancePenalty = c.inheritancePenalty
+        var
+          bestPenatly = maxInheritancePenalty
+          bestMatch = isNone
+        for kid in effectiveArgType.kids:
+          let x = typeRel(c, f, kid, flags)
+          if x > bestMatch:
+            bestMatch = x
+            bestPenatly = c.inheritancePenalty
+          c.inheritancePenalty = oldInheritancePenalty
+        c.inheritancePenalty = oldInheritancePenalty
+        if bestMatch > isNone:
+          c.inheritancePenalty = bestPenatly
+          result = bestMatch
       else:
         return isNone
   of tyUserTypeClassInst, tyUserTypeClass:

From 8644fca5295456799a53cb16435eb87998ea107a Mon Sep 17 00:00:00 2001
From: Ryan McConnell <rammcconnell@gmail.com>
Date: Wed, 17 Sep 2025 11:59:53 -0400
Subject: [PATCH 2/4] add test

---
 tests/typerel/tsigmatch.nim | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/typerel/tsigmatch.nim b/tests/typerel/tsigmatch.nim
index 7541f2028d444..c92c1cc339649 100644
--- a/tests/typerel/tsigmatch.nim
+++ b/tests/typerel/tsigmatch.nim
@@ -4,3 +4,16 @@ block: # bug #13618
 
   doAssert test(^1) == 1
   doAssert test(1) == 1
+
+block: # #25174
+  type Foo = object
+  type Bar = object
+  type Quz = object
+
+  proc bar[T: Foo | Bar](x: T): string =
+    return $typeof(T)
+  proc bar[T: object](x: T): string =
+    return $typeof(T)
+  doAssert bar(Foo()) == "Foo"
+  doAssert bar(Bar()) == "Bar"
+  doAssert bar(Quz()) == "Quz"

From bc88a53ba3927c296959fdb323c64cbc594535d2 Mon Sep 17 00:00:00 2001
From: Ryan McConnell <rammcconnell@gmail.com>
Date: Wed, 17 Sep 2025 15:49:28 -0400
Subject: [PATCH 3/4] simplify

---
 compiler/sigmatch.nim | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 01ace6a72fc70..2eed7b55887a4 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -1892,20 +1892,11 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
         if doBind: put(c, f, a)
         return isGeneric
       elif effectiveArgType.kind == tyOr:
-        let oldInheritancePenalty = c.inheritancePenalty
-        var
-          bestPenatly = maxInheritancePenalty
-          bestMatch = isNone
         for kid in effectiveArgType.kids:
-          let x = typeRel(c, f, kid, flags)
-          if x > bestMatch:
-            bestMatch = x
-            bestPenatly = c.inheritancePenalty
-          c.inheritancePenalty = oldInheritancePenalty
-        c.inheritancePenalty = oldInheritancePenalty
-        if bestMatch > isNone:
-          c.inheritancePenalty = bestPenatly
-          result = bestMatch
+          if typeRel(c, f, kid, flags) >= isSubtype:
+            result = isGeneric
+            #if doBind: put(c, f, kid)
+            break
       else:
         return isNone
   of tyUserTypeClassInst, tyUserTypeClass:

From bbeeb4ebf7fbb353d6398b8e00f6d7f96b4adba9 Mon Sep 17 00:00:00 2001
From: Ryan McConnell <rammcconnell@gmail.com>
Date: Sat, 20 Sep 2025 14:00:15 -0400
Subject: [PATCH 4/4] adjust generic inv

---
 compiler/sigmatch.nim | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 2eed7b55887a4..21697f33d3438 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -1742,7 +1742,17 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
       if ff != nil:
         result = typeRel(c, ff, a, flags)
   of tyGenericInvocation:
-    var x = a.skipGenericAlias
+    var x = a
+    while x != nil:
+      if x.kind == tyAlias:
+        x = x.last
+      elif x.isGenericAlias:
+        if f[0] == x[0]:
+          break
+        else:
+          x = x.last
+      else:
+        break
     if x.kind == tyGenericParam and x.len > 0:
       x = x.last
     let concpt = f.reduceToBase
@@ -1751,7 +1761,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
       preventHack = true
       x = x.last
     # XXX: This is very hacky. It should be moved back into liftTypeParam
-    if x.kind in {tyGenericInst, tyArray} and
+    if x.kind in {tyArray} and
       c.calleeSym != nil and
       c.calleeSym.kind in {skProc, skFunc} and c.call != nil and not preventHack:
       let inst = prepareMetatypeForSigmatch(c.c, c.bindings, c.call.info, f)
@@ -1807,10 +1817,12 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
           else:
             let key = f[i]
             let old = lookup(c.bindings, key)
-            if old == nil:
+            if typeRel(c, key, x, flags) == isNone:
+              result = isNone
+            elif old == nil or typeRel(c, old, x, flags + {trDontBind}) > isNone:
               put(c, key, x)
-            elif typeRel(c, old, x, flags + {trDontBind}) == isNone:
-              return isNone
+            else:
+              result = isNone
       var depth = -1
       if fobj != nil and aobj != nil and askip == fskip:
         depth = isObjectSubtype(c, aobj, fobj, f)
@@ -1895,7 +1907,6 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
         for kid in effectiveArgType.kids:
           if typeRel(c, f, kid, flags) >= isSubtype:
             result = isGeneric
-            #if doBind: put(c, f, kid)
             break
       else:
         return isNone