Origami404 updated this revision to Diff 477482.
Origami404 added a comment.
Update release notes.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D137343/new/
https://reviews.llvm.org/D137343
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaType.cpp
clang/test/Sema/warn-vla.c
Index: clang/test/Sema/warn-vla.c
===================================================================
--- clang/test/Sema/warn-vla.c
+++ clang/test/Sema/warn-vla.c
@@ -1,12 +1,39 @@
-// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify -Wvla %s
-// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify -Wvla %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify=expected,no-fallback-c99 -Wvla -Wvla-stack-allocation %s
+// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify=expected,no-fallback-c89 -Wvla -Wvla-stack-allocation %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify=expected,fallback -Wvla %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify=expected,only-stack-allocation -Wvla-stack-allocation -Wno-vla %s
void test1(int n) {
- int v[n]; // expected-warning {{variable length array}}
+ int v[n]; /* no-fallback-c89-warning {{variable length arrays are a C99 feature}}
+ no-fallback-c99-warning {{variable length array that may require stack allocation used}}
+ fallback-warning {{variable length array used}}
+ only-stack-allocation-warning {{variable length array that may require stack allocation used}}
+ */
}
-void test2(int n, int v[n]) { // expected-warning {{variable length array}}
+void test2(int n, int v[n]) { /* no-fallback-c89-warning {{variable length arrays are a C99 feature}}
+ no-fallback-c99-warning {{variable length array used}}
+ fallback-warning {{variable length array used}}
+ */
}
-void test3(int n, int v[n]); // expected-warning {{variable length array}}
+void test3(int n, int v[n]); /* no-fallback-c89-warning {{variable length arrays are a C99 feature}}
+ no-fallback-c99-warning {{variable length array used}}
+ fallback-warning {{variable length array used}}
+ */
+int test4_num;
+typedef int Test4[test4_num]; /* no-fallback-c89-warning {{variable length arrays are a C99 feature}}
+ no-fallback-c99-warning {{variable length array used}}
+ fallback-warning {{variable length array used}}
+ expected-error {{variable length array declaration not allowed at file scope}}
+ */
+
+void test5() {
+ typedef int type[test4_num]; /* no-fallback-c89-warning {{variable length arrays are a C99 feature}}
+ no-fallback-c99-warning {{variable length array that may require stack allocation used}}
+ fallback-warning {{variable length array used}}
+ only-stack-allocation-warning {{variable length array that may require stack allocation used}}
+ */
+
+}
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -22,6 +22,7 @@
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeLocVisitor.h"
+#include "clang/Basic/DiagnosticSema.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
@@ -2530,7 +2531,8 @@
return QualType();
}
- // VLAs always produce at least a -Wvla diagnostic, sometimes an error.
+ // VLAs always produce at least a -Wvla-portability or -Wvla-stack-allocation
+ // diagnostic, sometimes an error.
unsigned VLADiag;
bool VLAIsError;
if (getLangOpts().OpenCL) {
@@ -2538,7 +2540,26 @@
VLADiag = diag::err_opencl_vla;
VLAIsError = true;
} else if (getLangOpts().C99) {
- VLADiag = diag::warn_vla_used;
+ // after C99, VLA is no longer an extension.
+ if (getCurScope()->getFlags() == Scope::ScopeFlags::DeclScope) {
+ // VLA in file scope typedef will have an error, and should not have a
+ // warning of portability. But for backward compatibility, we preform the
+ // exact same action like before (which will give an warning of "vla
+ // used").
+ VLADiag = diag::warn_vla_portability;
+ } else if (getCurScope()->isFunctionPrototypeScope()) {
+ // VLA in function prototype is acceptable by C2x standard
+ // so just give a protability warning
+ VLADiag = diag::warn_vla_portability;
+ } else {
+ // in other case, a VLA will cause stack allocation
+ // if -Wvla-stack-allocation is ignored, fallback to
+ // -Wvla-protability
+ if (getDiagnostics().isIgnored(diag::warn_vla_stack_allocation, Loc))
+ VLADiag = diag::warn_vla_portability;
+ else
+ VLADiag = diag::warn_vla_stack_allocation;
+ }
VLAIsError = false;
} else if (isSFINAEContext()) {
VLADiag = diag::err_vla_in_sfinae;
@@ -2547,6 +2568,7 @@
VLADiag = diag::err_openmp_vla_in_task_untied;
VLAIsError = true;
} else {
+ // Before C99 and in most of platform, VLA is an extension.
VLADiag = diag::ext_vla;
VLAIsError = false;
}
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -131,8 +131,10 @@
// C99 variable-length arrays
def ext_vla : Extension<"variable length arrays are a C99 feature">,
InGroup<VLAExtension>;
-def warn_vla_used : Warning<"variable length array used">,
+def warn_vla_portability : Warning<"variable length array used">,
InGroup<VLA>, DefaultIgnore;
+def warn_vla_stack_allocation : Warning<"variable length array that may require stack allocation used">,
+ InGroup<VLAStackAllocation>, DefaultIgnore;
def err_vla_in_sfinae : Error<
"variable length array cannot be formed during template argument deduction">;
def err_array_star_in_function_definition : Error<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -828,6 +828,7 @@
def VexingParse : DiagGroup<"vexing-parse">;
def VLAExtension : DiagGroup<"vla-extension">;
def VLA : DiagGroup<"vla", [VLAExtension]>;
+def VLAStackAllocation : DiagGroup<"vla-stack-allocation", [VLA]>;
def VolatileRegisterVar : DiagGroup<"volatile-register-var">;
def Visibility : DiagGroup<"visibility">;
def ZeroLengthArray : DiagGroup<"zero-length-array">;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -456,6 +456,17 @@
int b[0]; // NOT a flexible array member.
};
+- Added ``-Wvla-stack-allocation`` to only give warnings about VLA that need
+ stack allocation.
+
+ .. code-block:: C
+
+ void f(int n) {
+ int a[n]; // VLA that needs stack allocation
+ }
+
+ void g(int n, int a[n]) {} // VLA that don't need stack allocation
+
Deprecated Compiler Flags
-------------------------
- ``-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang``
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