================
@@ -4522,6 +4523,38 @@ static CompleteObject findCompleteObject(EvalInfo &Info,
const Expr *E,
BaseVal = MTE->getOrCreateValue(false);
assert(BaseVal && "got reference to unevaluated temporary");
+ } else if (const CompoundLiteralExpr *CLE =
+ dyn_cast_or_null<CompoundLiteralExpr>(Base)) {
+ // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating
+ // the initializer until now for such expressions. Such an expression
+ // can't be an ICE in C, so this only matters for fold.
+ if (LValType.isVolatileQualified()) {
+ Info.FFDiag(E);
+ return CompleteObject();
+ }
+
+ // According to GCC info page:
+ //
+ // 6.28 Compound Literals
+ //
+ // As an optimization, G++ sometimes gives array compound literals
+ // longer lifetimes: when the array either appears outside a function
or
+ // has a const-qualified type. If foo and its initializer had elements
+ // of type char *const rather than char *, or if foo were a global
+ // variable, the array would have static storage duration. But it is
+ // probably safest just to avoid the use of array compound literals in
+ // C++ code.
+ //
+ // Obey that rule by checking constness for converted array types.
+ if (QualType CLETy = CLE->getType(); CLETy->isArrayType() &&
+ !LValType->isArrayType() &&
----------------
kadircet wrote:
oops, I was looking at the wrong terminal, we do have failures without this:
```
********************
FAIL: Clang :: SemaCXX/constant-expression-cxx11.cpp (3207 of 22469)
******************** TEST 'Clang :: SemaCXX/constant-expression-cxx11.cpp'
FAILED ********************
Exit Code: 1
Command Output (stderr):
--
/usr/local/google/home/kadircet/repos/llvm/build/bin/clang -cc1
-internal-isystem
/usr/local/google/home/kadircet/repos/llvm/build/lib/clang/21/include
-nostdsysteminc -std=c++23 -isystem
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/Inputs
-fsyntax-only -verify=expected,cxx20_23,cxx23 -triple x86_64-linux
-Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array
-Wno-c99-designator -fcxx-exceptions -pedantic
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
-Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion # RUN: at
line 1
+ /usr/local/google/home/kadircet/repos/llvm/build/bin/clang -cc1
-internal-isystem
/usr/local/google/home/kadircet/repos/llvm/build/lib/clang/21/include
-nostdsysteminc -std=c++23 -isystem
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/Inputs
-fsyntax-only -verify=expected,cxx20_23,cxx23 -triple x86_64-linux
-Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array
-Wno-c99-designator -fcxx-exceptions -pedantic
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
-Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
error: diagnostics with 'error' severity expected but not seen:
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1670 'expected-error': static assertion expression is not an integral
constant expression
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1673 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp:1674)
'expected-error': static assertion expression is not an integral constant
expression
error: diagnostics with 'note' severity expected but not seen:
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1670 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp:1671)
'expected-note': subexpression not valid
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1669 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp:1672)
'expected-note': declared here
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1673 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp:1675)
'expected-note': subexpression not valid
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp
Line 1673 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaCXX/constant-expression-cxx11.cpp:1676)
'expected-note': declared here
6 errors generated.
--
********************
FAIL: Clang :: SemaTemplate/constexpr-instantiate.cpp (13593 of 22469)
******************** TEST 'Clang :: SemaTemplate/constexpr-instantiate.cpp'
FAILED ********************
Exit Code: 1
Command Output (stderr):
--
/usr/local/google/home/kadircet/repos/llvm/build/bin/clang -cc1
-internal-isystem
/usr/local/google/home/kadircet/repos/llvm/build/lib/clang/21/include
-nostdsysteminc -std=c++11 -verify
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
# RUN: at line 1
+ /usr/local/google/home/kadircet/repos/llvm/build/bin/clang -cc1
-internal-isystem
/usr/local/google/home/kadircet/repos/llvm/build/lib/clang/21/include
-nostdsysteminc -std=c++11 -verify
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
error: 'expected-error' diagnostics expected but not seen:
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 222 (directive at
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp:223):
must be initialized by a constant expression
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 236: narrow
error: 'expected-note' diagnostics expected but not seen:
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 222: not valid in a constant expression
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 222: declared here
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 236: instantiation of
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 236: cast
File
/usr/local/google/home/kadircet/repos/llvm/clang/test/SemaTemplate/constexpr-instantiate.cpp
Line 237: instantiation of
7 errors generated.
--
********************
```
https://github.com/llvm/llvm-project/pull/137163
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