From ce238dd878038bf857968931773cc9b10f3b225d Mon Sep 17 00:00:00 2001
From: Julius Ikkala <julius.ikkala@gmail.com>
Date: Thu, 22 May 2025 22:10:42 +0300
Subject: Make sizeof(T) & alignof(T) of generic types work as compile-time
 constants (#7213)

* Make sizeof(generic) work as compile-time constant

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
---
 source/slang/slang-check-expr.cpp | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

(limited to 'source/slang/slang-check-expr.cpp')

diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index ad36a7e4a..db507c060 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -2060,13 +2060,25 @@ IntVal* SemanticsVisitor::tryConstantFoldExpr(
         }
     }
 
-    if (auto countOfExpr = expr.as<CountOfExpr>())
+    if (auto sizeOfLikeExpr = expr.as<SizeOfLikeExpr>())
     {
-        auto type =
-            as<Type>(countOfExpr.getExpr()->sizedType->substitute(m_astBuilder, expr.getSubsts()));
-        if (type)
+        auto type = as<Type>(
+            sizeOfLikeExpr.getExpr()->sizedType->substitute(m_astBuilder, expr.getSubsts()));
+
+        if (auto sizeOfExpr = expr.as<SizeOfExpr>())
+        {
+            return as<IntVal>(SizeOfIntVal::tryFold(m_astBuilder, expr.getExpr()->type.type, type));
+        }
+        else if (auto alignOfExpr = expr.as<AlignOfExpr>())
+        {
+            return as<IntVal>(
+                AlignOfIntVal::tryFold(m_astBuilder, expr.getExpr()->type.type, type));
+        }
+        else if (auto countOfExpr = expr.as<CountOfExpr>())
+        {
             return as<IntVal>(
                 CountOfIntVal::tryFold(m_astBuilder, expr.getExpr()->type.type, type));
+        }
     }
 
     // it is possible that we are referring to a generic value param
@@ -2159,20 +2171,6 @@ IntVal* SemanticsVisitor::tryConstantFoldExpr(
         if (val)
             return val;
     }
-    else if (auto sizeOfLikeExpr = as<SizeOfLikeExpr>(expr.getExpr()))
-    {
-        ASTNaturalLayoutContext context(getASTBuilder(), nullptr);
-        const auto size = context.calcSize(sizeOfLikeExpr->sizedType);
-        if (!size)
-        {
-            return nullptr;
-        }
-
-        auto value = as<AlignOfExpr>(sizeOfLikeExpr) ? size.alignment : size.size;
-
-        // We can return as an IntVal
-        return getASTBuilder()->getIntVal(expr.getExpr()->type, value);
-    }
     else if (auto indexExpr = expr.as<IndexExpr>())
     {
         return tryFoldIndexExpr(indexExpr.getExpr(), kind, circularityInfo);
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