[clang] a9af8f8 - [clang][Interp] Implement IntegralAP::truncate() (#69912)

[via cfe-commits]

Author: Timm Baeder
Date: 2023-11-05T08:26:29+01:00
New Revision: a9af8f8882f9d64870d3b60adfbe07e59c63c523

URL: https://github.com/llvm/llvm-project/commit/a9af8f8882f9d64870d3b60adfbe07e59c63c523
DIFF: https://github.com/llvm/llvm-project/commit/a9af8f8882f9d64870d3b60adfbe07e59c63c523.diff

LOG: [clang][Interp] Implement IntegralAP::truncate() (#69912)

Added: 
    

Modified: 
    clang/lib/AST/Interp/IntegralAP.h
    clang/test/AST/Interp/intap.cpp

Removed: 
    


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diff  --git a/clang/lib/AST/Interp/IntegralAP.h b/clang/lib/AST/Interp/IntegralAP.h
index 9aefea6d0c47ed9..1f535d420bcd54b 100644
--- a/clang/lib/AST/Interp/IntegralAP.h
+++ b/clang/lib/AST/Interp/IntegralAP.h
@@ -140,9 +140,8 @@ template <bool Signed> class IntegralAP final {
     return NameStr;
   }
 
-  IntegralAP truncate(unsigned bitWidth) const {
-    assert(false);
-    return V;
+  IntegralAP truncate(unsigned BitWidth) const {
+    return IntegralAP(V.trunc(BitWidth));
   }
 
   IntegralAP<false> toUnsigned() const {

diff  --git a/clang/test/AST/Interp/intap.cpp b/clang/test/AST/Interp/intap.cpp
index 02a860eb0986c15..db9f516131af474 100644
--- a/clang/test/AST/Interp/intap.cpp
+++ b/clang/test/AST/Interp/intap.cpp
@@ -121,4 +121,20 @@ namespace AddSubOffset {
   static_assert(*P2 == 1,"");
 }
 
+namespace Bitfields {
+  struct S1 {
+    unsigned _BitInt(128) a : 2;
+  };
+  constexpr S1 s1{100}; // ref-warning {{changes value from 100 to 0}} \
+                        // expected-warning {{changes value from 100 to 0}}
+  constexpr S1 s12{3};
+  static_assert(s12.a == 3, "");
+
+  struct S2 {
+    unsigned __int128 a : 2;
+  };
+  constexpr S2 s2{100}; // ref-warning {{changes value from 100 to 0}} \
+                        // expected-warning {{changes value from 100 to 0}}
+}
+
 #endif