Commit f8d448d5 authored by Aaron Ballman's avatar Aaron Ballman
Browse files

Correct behavior of VLA extension diagnostic in C89 mode 

Post-commit feedback (https://reviews.llvm.org/D156565#4654773) found
that the changes in 84a3aadf caused us
to diagnose use of VLAs in C89 mode by default which was an unintended
change.

This adds -Wvla-cxx-extension as a warning group and adds the C++-
specific warnings to it while leaving the C warnings under
-Wvla-extension. -Wvla-cxx-extension is then added to -Wall.
parent b507509f

clang/include/clang/Basic/DiagnosticGroups.td

+4 −2
Original line number Diff line number Diff line
@@ -849,7 +849,8 @@ def VariadicMacros : DiagGroup<"variadic-macros">; 
def VectorConversion : DiagGroup<"vector-conversion">;      // clang specific

def VexingParse : DiagGroup<"vexing-parse">;

def VLAUseStaticAssert : DiagGroup<"vla-extension-static-assert">;

def VLAExtension : DiagGroup<"vla-extension", [VLAUseStaticAssert]>;

def VLACxxExtension : DiagGroup<"vla-cxx-extension", [VLAUseStaticAssert]>;

def VLAExtension : DiagGroup<"vla-extension", [VLACxxExtension]>;

def VLA : DiagGroup<"vla", [VLAExtension]>;

def VolatileRegisterVar : DiagGroup<"volatile-register-var">;

def Visibility : DiagGroup<"visibility">;
@@ -1086,7 +1087,8 @@ def Consumed : DiagGroup<"consumed">; 
// warning should be active _only_ when -Wall is passed in, mark it as

// DefaultIgnore in addition to putting it here.

def All : DiagGroup<"all", [Most, Parentheses, Switch, SwitchBool,

                            MisleadingIndentation, PackedNonPod, VLAExtension]>;

                            MisleadingIndentation, PackedNonPod,

                            VLACxxExtension]>;



// Warnings that should be in clang-cl /w4.

def : DiagGroup<"CL4", [All, Extra]>;

clang/include/clang/Basic/DiagnosticSemaKinds.td

+2 −2
Original line number Diff line number Diff line
@@ -141,9 +141,9 @@ def ext_vla : Extension<"variable length arrays are a C99 feature">, 
// language modes, we warn as an extension but add the warning group to -Wall.

def ext_vla_cxx : ExtWarn<

  "variable length arrays in C++ are a Clang extension">,

  InGroup<VLAExtension>;

  InGroup<VLACxxExtension>;

def ext_vla_cxx_in_gnu_mode : Extension<ext_vla_cxx.Summary>,

  InGroup<VLAExtension>;

  InGroup<VLACxxExtension>;

def ext_vla_cxx_static_assert : ExtWarn<

  "variable length arrays in C++ are a Clang extension; did you mean to use "

  "'static_assert'?">, InGroup<VLAUseStaticAssert>;

clang/test/Misc/warning-wall.c

+1 −1
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ CHECK-NEXT: -Wswitch 
CHECK-NEXT:  -Wswitch-bool

CHECK-NEXT:  -Wmisleading-indentation

CHECK-NEXT:  -Wpacked-non-pod

CHECK-NEXT:  -Wvla-extension

CHECK-NEXT:  -Wvla-cxx-extension

CHECK-NEXT:    -Wvla-extension-static-assert



CHECK-NOT:-W

clang/test/Sema/vla-ext.c

0 → 100644
+24 −0
Original line number Diff line number Diff line 
/* RUN: %clang_cc1 -verify=off -std=c89 %s

 * RUN: %clang_cc1 -verify=off -Wall -std=c89 %s

 * RUN: %clang_cc1 -verify -pedantic -std=c89 %s

 * RUN: %clang_cc1 -verify -Wvla-extension -std=c89 %s

 * RUN: %clang_cc1 -verify=off -Wvla-cxx-extension -std=c89 %s

 * RUN: %clang_cc1 -verify=off -pedantic -std=c99 %s

 * RUN: %clang_cc1 -verify=off -Wall -std=c99 %s

 * RUN: %clang_cc1 -verify=off -std=c99 -Wvla-extension %s

 * The next run line still issues the extension warning because VLAs are an

 * extension in C89, but the line after it will issue the congratulatory

 * diagnostic.

 * RUN: %clang_cc1 -verify -Wvla -std=c89 %s

 * RUN: %clang_cc1 -verify=wvla -Wvla -std=c99 %s

 */



/* off-no-diagnostics */



void func(int n) {

  int array[n]; /* expected-warning {{variable length arrays are a C99 feature}}

                   wvla-warning {{variable length array used}}

                 */

  (void)array;

}