[flang] Add a warning for CDEFINED declarations that have initializers #159456
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CDEFINED declarations are similar to "extern" declarations in C. If
they have initializers, this could lead to linker errors. clang warns
about "extern" declarations with initializers. Add similar warning
to flang:
```
$ flang -c cdefined.f90 -pedantic
./cdefined.f90:3:57: warning: CDEFINED variable should not have an initializer [-Wcdefined-init]
integer(c_int), bind(C, name='c_global', CDEFINED) :: c = 4
^
```
llvmbot
added
flang
|
@llvm/pr-subscribers-flang-semantics Author: Eugene Epshteyn (eugeneepshteyn) ChangesCDEFINED declarations are similar to "extern" declarations in C. If they have initializers, this could lead to linker errors. clang warns about "extern" declarations with initializers. Add similar warning to flang: Full diff: https://github.com/llvm/llvm-project/pull/159456.diff 3 Files Affected:
diff --git a/flang/include/flang/Support/Fortran-features.h b/flang/include/flang/Support/Fortran-features.h
index 83a75b0efcb55..89d1dba7a2dc8 100644
--- a/flang/include/flang/Support/Fortran-features.h
+++ b/flang/include/flang/Support/Fortran-features.h
@@ -73,7 +73,7 @@ ENUM_CLASS(UsageWarning, Portability, PointerToUndefinable,
ZeroDoStep, UnusedForallIndex, OpenMPUsage, DataLength, IgnoredDirective,
HomonymousSpecific, HomonymousResult, IgnoredIntrinsicFunctionType,
PreviousScalarUse, RedeclaredInaccessibleComponent, ImplicitShared,
- IndexVarRedefinition, IncompatibleImplicitInterfaces,
+ IndexVarRedefinition, IncompatibleImplicitInterfaces, CdefinedInit,
VectorSubscriptFinalization, UndefinedFunctionResult, UselessIomsg,
MismatchingDummyProcedure, SubscriptedEmptyArray, UnsignedLiteralTruncation,
CompatibleDeclarationsFromDistinctModules,
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index d0d3b0e1caa5a..cdd8d6ff2f60e 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -9118,6 +9118,9 @@ void DeclarationVisitor::NonPointerInitialization(
if (details->init()) {
SayWithDecl(name, *name.symbol,
"'%s' has already been initialized"_err_en_US);
+ } else if (details->isCDefined()) {
+ context().Warn(common::UsageWarning::CdefinedInit, name.source,
+ "CDEFINED variable should not have an initializer"_warn_en_US);
} else if (IsAllocatable(ultimate)) {
Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
} else if (ultimate.owner().IsParameterizedDerivedType()) {
diff --git a/flang/test/Semantics/cdefined.f90 b/flang/test/Semantics/cdefined.f90
new file mode 100644
index 0000000000000..84103ce661d0b
--- /dev/null
+++ b/flang/test/Semantics/cdefined.f90
@@ -0,0 +1,6 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1 -pedantic -Werror
+module m
+ use iso_c_binding
+ !WARNING: CDEFINED variable should not have an initializer [-Wcdefined-init]
+ integer(c_int), bind(C, name='c_global', CDEFINED) :: c = 42
+end
|
klausler
approved these changes
Sep 17, 2025
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CDEFINED declarations are similar to "extern" declarations in C. If they have initializers, this could lead to linker errors. clang warns about "extern" declarations with initializers. Add similar warning to flang: