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This patch implements a warning for uninitialized elements in fixed-size arrays.
Without warnings a 'gap' in an array can go unnoticed when the size increases.
Consider what happens with the array `const char *err_msg[ERR_TYPE_COUNT]` when
a new `ERR_..` enum value is added.
Note: There is most likely a better way of doing this (first encounter with
llvm internals), but I hope it will get some eyes on the problem such that it
can be merged soon-ish.
Related: https://github.com/llvm/llvm-project/issues/22692
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D152083
Files:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaInit.cpp
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -980,6 +980,22 @@
if (RequiresSecondPass && !hadError)
FillInEmptyInitializations(Entity, FullyStructuredList,
RequiresSecondPass, nullptr, 0);
+
+ if (const ConstantArrayType *CAType = dyn_cast<ConstantArrayType>(T)) {
+ if (FullyStructuredList->getNumInits() <
CAType->getSize().getZExtValue()) {
+ S.Diag(IL->getBeginLoc(), diag::warn_uninit_fixed_size_array)
+ << IL->getSourceRange();
+ } else {
+ Expr **inits = FullyStructuredList->getInits();
+ for (unsigned i = 0, e = FullyStructuredList->getNumInits(); i != e;
++i) {
+ if (inits[i] == nullptr) {
+ S.Diag(IL->getBeginLoc(), diag::warn_uninit_fixed_size_array)
+ << IL->getSourceRange();
+ break;
+ }
+ }
+ }
+ }
}
if (hadError && FullyStructuredList)
FullyStructuredList->markError();
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2214,6 +2214,9 @@
"reference %0 is not yet bound to a value when used within its own"
" initialization">,
InGroup<Uninitialized>;
+def warn_uninit_fixed_size_array : Warning<
+ "fixed-size array contains uninitialized elements">,
+ InGroup<Uninitialized>, DefaultIgnore;
def warn_uninit_var : Warning<
"variable %0 is uninitialized when %select{used here|captured by block}1">,
InGroup<Uninitialized>, DefaultIgnore;
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -980,6 +980,22 @@
if (RequiresSecondPass && !hadError)
FillInEmptyInitializations(Entity, FullyStructuredList,
RequiresSecondPass, nullptr, 0);
+
+ if (const ConstantArrayType *CAType = dyn_cast<ConstantArrayType>(T)) {
+ if (FullyStructuredList->getNumInits() < CAType->getSize().getZExtValue()) {
+ S.Diag(IL->getBeginLoc(), diag::warn_uninit_fixed_size_array)
+ << IL->getSourceRange();
+ } else {
+ Expr **inits = FullyStructuredList->getInits();
+ for (unsigned i = 0, e = FullyStructuredList->getNumInits(); i != e; ++i) {
+ if (inits[i] == nullptr) {
+ S.Diag(IL->getBeginLoc(), diag::warn_uninit_fixed_size_array)
+ << IL->getSourceRange();
+ break;
+ }
+ }
+ }
+ }
}
if (hadError && FullyStructuredList)
FullyStructuredList->markError();
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2214,6 +2214,9 @@
"reference %0 is not yet bound to a value when used within its own"
" initialization">,
InGroup<Uninitialized>;
+def warn_uninit_fixed_size_array : Warning<
+ "fixed-size array contains uninitialized elements">,
+ InGroup<Uninitialized>, DefaultIgnore;
def warn_uninit_var : Warning<
"variable %0 is uninitialized when %select{used here|captured by block}1">,
InGroup<Uninitialized>, DefaultIgnore;
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