[PATCH] D132952: [Sema] disable -Wvla for function array parameters

[YingChi Long via Phabricator via cfe-commits]

inclyc created this revision.
inclyc added a reviewer: aaron.ballman.
Herald added a project: All.
inclyc added reviewers: rsmith, clang-language-wg.
inclyc published this revision for review.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Fixes: https://github.com/llvm/llvm-project/issues/57098


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132952

Files:
  clang/include/clang/Sema/Sema.h
  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
@@ -5,8 +5,18 @@
   int v[n]; // expected-warning {{variable length array}}
 }
 
-void test2(int n, int v[n]) { // expected-warning {{variable length array}}
+void test2(int n, int v[n]) { // c99 no-warning
+#if __STDC_VERSION__ < 199901L
+// expected-warning at -2{{variable length arrays are a C99 feature}}
+#endif
 }
 
-void test3(int n, int v[n]); // expected-warning {{variable length array}}
+void test3(int n, int v[n]); // c99 no-warning
+#if __STDC_VERSION__ < 199901L
+// expected-warning at -2{{variable length arrays are a C99 feature}}
+#endif
 
+void test4(int n, int v[][*]); // c99 no-warning
+#if __STDC_VERSION__ < 199901L
+// expected-warning at -2{{variable length arrays are a C99 feature}}
+#endif
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -2367,9 +2367,11 @@
     unsigned VLADiag;
     bool VLAIsError;
     bool IsVLA = false;
+    bool SuppressNotICEVLA = false;
 
-    VLADiagnoser(unsigned VLADiag, bool VLAIsError)
-        : VLADiag(VLADiag), VLAIsError(VLAIsError) {}
+    VLADiagnoser(unsigned VLADiag, bool VLAIsError, bool SuppressNotICEVLA)
+        : VLADiag(VLADiag), VLAIsError(VLAIsError),
+          SuppressNotICEVLA(SuppressNotICEVLA) {}
 
     Sema::SemaDiagnosticBuilder diagnoseNotICEType(Sema &S, SourceLocation Loc,
                                                    QualType T) override {
@@ -2379,14 +2381,18 @@
     Sema::SemaDiagnosticBuilder diagnoseNotICE(Sema &S,
                                                SourceLocation Loc) override {
       IsVLA = !VLAIsError;
-      return S.Diag(Loc, VLADiag);
+      if (!SuppressNotICEVLA)
+        return S.Diag(Loc, VLADiag);
+      return Sema::SemaDiagnosticBuilder(S);
     }
 
     Sema::SemaDiagnosticBuilder diagnoseFold(Sema &S,
                                              SourceLocation Loc) override {
       return S.Diag(Loc, diag::ext_vla_folded_to_constant);
     }
-  } Diagnoser(VLADiag, VLAIsError);
+  } Diagnoser(VLADiag, VLAIsError,
+              S.getCurScope()->isFunctionPrototypeScope() &&
+                  VLADiag == diag::warn_vla_used);
 
   ExprResult R =
       S.VerifyIntegerConstantExpression(ArraySize, &SizeVal, Diagnoser);
@@ -2528,7 +2534,9 @@
   llvm::APSInt ConstVal(Context.getTypeSize(Context.getSizeType()));
   if (!ArraySize) {
     if (ASM == ArrayType::Star) {
-      Diag(Loc, VLADiag);
+      if (!(getCurScope()->isFunctionPrototypeScope() &&
+            VLADiag == diag::warn_vla_used))
+        Diag(Loc, VLADiag);
       if (VLAIsError)
         return QualType();
 
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -1756,6 +1756,8 @@
       K_Deferred
     };
 
+    // Special builder emitting no diagnostics
+    SemaDiagnosticBuilder(Sema &S) : S(S) {}
     SemaDiagnosticBuilder(Kind K, SourceLocation Loc, unsigned DiagID,
                           FunctionDecl *Fn, Sema &S);
     SemaDiagnosticBuilder(SemaDiagnosticBuilder &&D);


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