serge-sans-paille created this revision.
serge-sans-paille added reviewers: RKSimon, aaron.ballman, tstellar.
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This warning exist in GCC[0] and warns about re-declarations of functions
involving arguments of array or pointer types of inconsistent kinds or forms.
This is not the exact same implementation as GCC's : there's no warning level
and that flag has no effect on -Warray-bounds.
[0]
https://gcc.gnu.org/onlinedocs/gcc-12.1.0/gcc/Warning-Options.html#index-Wno-array-parameter
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D128449
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/test/Sema/array-parameter.c
Index: clang/test/Sema/array-parameter.c
===================================================================
--- /dev/null
+++ clang/test/Sema/array-parameter.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fsyntax-only -Wno-unused -verify %s
+
+void f0(int a[]);
+void f0(int *a); // no warning
+
+void f1(int a[]); // expected-note {{previously declared as int[] here}}
+void f1(int a[2]); // expected-warning {{argument 'a' of type 'int[2]' with mismatched bound}}
+
+void f2(int a[3]); // expected-note {{previously declared as int[3] here}}
+void f2(int a[2]); // expected-warning {{argument 'a' of type 'int[2]' with mismatched bound}}
+
+void f3(int a[const 2]); // expected-note {{previously declared as int[const 2] here}}
+void f3(int a[2]); // expected-warning {{argument 'a' of type 'int[2]' with mismatched bound}}
+
+void f4(int a[static 2]); // expected-note {{previously declared as int[static 2] here}}
+void f4(int a[2]); // expected-warning {{argument 'a' of type 'int[2]' with mismatched bound}}
+
+void f5(int a[restrict 2]); // expected-note {{previously declared as int[__restrict 2] here}}
+void f5(int a[2]); // expected-warning {{argument 'a' of type 'int[2]' with mismatched bound}}
+
+void f6(int a[*]); // expected-note {{previously declared as int[*] here}}
+void f6(int a[]); // expected-warning {{argument 'a' of type 'int[]' with mismatched bound}}
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -46,6 +46,7 @@
#include "clang/Sema/Template.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Triple.h"
+#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cstring>
#include <functional>
@@ -3209,6 +3210,19 @@
if (!foundAny) newDecl->dropAttrs();
}
+static bool EquivalentArrayTypes(QualType Old, QualType New) {
+ // type[] is equivalent to type *
+ if ((Old->isIncompleteArrayType() && New->isPointerType()) ||
+ (New->isIncompleteArrayType() && Old->isPointerType()))
+ return true;
+
+ // Don't try to compare VLA sizes
+ if (Old->isVariableArrayType() && New->isVariableArrayType())
+ return true;
+
+ return Old == New;
+}
+
static void mergeParamDeclTypes(ParmVarDecl *NewParam,
const ParmVarDecl *OldParam,
Sema &S) {
@@ -3234,6 +3248,22 @@
NewParam->setType(NewT);
}
}
+ const DecayedType *OldParamDT =
+ dyn_cast<const DecayedType>(OldParam->getType());
+ const DecayedType *NewParamDT =
+ dyn_cast<const DecayedType>(NewParam->getType());
+ if (OldParamDT && NewParamDT &&
+ OldParamDT->getPointeeType() == NewParamDT->getPointeeType()) {
+ QualType OldParamOT = OldParamDT->getOriginalType();
+ QualType NewParamOT = NewParamDT->getOriginalType();
+ if (!EquivalentArrayTypes(OldParamOT, NewParamOT)) {
+ S.Diag(NewParam->getLocation(), diag::warn_inconsistent_array_form)
+ << NewParam->getName()
+ << NewParamOT->getCanonicalTypeInternal().getAsString();
+ S.Diag(OldParam->getLocation(), diag::note_previous_declaration_as)
+ << OldParamOT->getCanonicalTypeInternal().getAsString();
+ }
+ }
}
namespace {
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9393,6 +9393,12 @@
def note_array_declared_here : Note<
"array %0 declared here">;
+def warn_inconsistent_array_form : Warning<
+ "argument '%0' of type '%1' with mismatched bound">,
+ InGroup<ArrayParameter>;
+def note_previous_declaration_as : Note<
+ "previously declared as %0 here">;
+
def warn_printf_insufficient_data_args : Warning<
"more '%%' conversions than data arguments">, InGroup<FormatInsufficientArgs>;
def warn_printf_data_arg_not_used : Warning<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -31,6 +31,7 @@
def GNUAutoType : DiagGroup<"gnu-auto-type">;
def ArrayBounds : DiagGroup<"array-bounds">;
def ArrayBoundsPointerArithmetic : DiagGroup<"array-bounds-pointer-arithmetic">;
+def ArrayParameter : DiagGroup<"array-parameter">;
def AutoDisableVptrSanitizer : DiagGroup<"auto-disable-vptr-sanitizer">;
def Availability : DiagGroup<"availability">;
def Section : DiagGroup<"section">;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -309,6 +309,9 @@
removed in the future once clang supports all such operations.
- Added the ``-print-diagnostic-options`` option, which prints a list of
warnings the compiler supports.
+- Added the ``-Warray-parameter`` warning. It detects function redefinition,
+ where different definition involve argument type that decay to the same
+ pointer type from different array types.
Deprecated Compiler Flags
-------------------------
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