[PATCH] D138321: [-Wunsafe-buffer-usage] Ignore array subscript on literal zero

[Ziqing Luo via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGf6c54cdbc439: [-Wunsafe-buffer-usage] Ignore array subscript on literal zero (authored by ziqingluo-90).

Changed prior to commit:
  https://reviews.llvm.org/D138321?vs=476581&id=483718#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138321/new/

https://reviews.llvm.org/D138321

Files:
  clang/lib/Analysis/UnsafeBufferUsage.cpp
  clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp


Index: clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
@@ -29,10 +29,10 @@
 char * charPtrCall(void);
 
 void testArraySubscripts(int *p, int **pp) {
-  foo(p[0],             // expected-warning{{unchecked operation on raw buffer in expression}}
-      pp[0][0],         // expected-warning2{{unchecked operation on raw buffer in expression}}
-      0[0[pp]],         // expected-warning2{{unchecked operation on raw buffer in expression}}
-      0[pp][0]          // expected-warning2{{unchecked operation on raw buffer in expression}}
+  foo(p[1],             // expected-warning{{unchecked operation on raw buffer in expression}}
+      pp[1][1],         // expected-warning2{{unchecked operation on raw buffer in expression}}
+      1[1[pp]],         // expected-warning2{{unchecked operation on raw buffer in expression}}
+      1[pp][1]          // expected-warning2{{unchecked operation on raw buffer in expression}}
       );
 
   if (p[3]) {           // expected-warning{{unchecked operation on raw buffer in expression}}
@@ -50,11 +50,18 @@
   int a[10], b[10][10];
 
   // Not to warn subscripts on arrays
-  foo(a[0], a[1],
-      0[a], 1[a],
+  foo(a[1], 1[a],
       b[3][4],
       4[b][3],
       4[3[b]]);
+
+  // Not to warn when index is zero
+  foo(p[0], pp[0][0], 0[0[pp]], 0[pp][0],
+      ((int*)voidPtrCall())[0],
+      0[(int*)voidPtrCall()],
+      charPtrCall()[0],
+      0[charPtrCall()]
+      );
 }
 
 void testArraySubscriptsWithAuto(int *p, int **pp) {
@@ -62,19 +69,19 @@
 
   auto ap1 = a;
 
-  foo(ap1[0]);  // expected-warning{{unchecked operation on raw buffer in expression}}
+  foo(ap1[1]);  // expected-warning{{unchecked operation on raw buffer in expression}}
 
   auto ap2 = p;
 
-  foo(ap2[0]);  // expected-warning{{unchecked operation on raw buffer in expression}}
+  foo(ap2[1]);  // expected-warning{{unchecked operation on raw buffer in expression}}
 
   auto ap3 = pp;
 
-  foo(ap3[0][0]); // expected-warning2{{unchecked operation on raw buffer in expression}}
+  foo(ap3[1][1]); // expected-warning2{{unchecked operation on raw buffer in expression}}
 
   auto ap4 = *pp;
 
-  foo(ap4[0]);  // expected-warning{{unchecked operation on raw buffer in expression}}
+  foo(ap4[1]);  // expected-warning{{unchecked operation on raw buffer in expression}}
 }
 
 void testUnevaluatedContext(int * p) {
Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -189,9 +189,9 @@
   static Matcher matcher() {
     // FIXME: What if the index is integer literal 0? Should this be
     // a safe gadget in this case?
-    return stmt(
-        arraySubscriptExpr(hasBase(ignoringParenImpCasts(hasPointerType())))
-            .bind(ArraySubscrTag));
+    return stmt(arraySubscriptExpr(hasBase(ignoringParenImpCasts(hasPointerType())),
+                                   unless(hasIndex(integerLiteral(equals(0)))))
+                .bind(ArraySubscrTag));
   }
 
   const ArraySubscriptExpr *getBaseStmt() const override { return ASE; }


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