[clang] [analyzer] Suppress out of bounds reports after weak loop assumptions (PR #109804)

[Donát Nagy via cfe-commits]

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@@ -194,3 +199,99 @@ char test_comparison_with_extent_symbol(struct incomplete *p) {
   return ((char *)p)[-1]; // no-warning
 }
 
+// WeakLoopAssumption suppression
+///////////////////////////////////////////////////////////////////////
+
+int GlobalArray[100];
+int loop_suppress_after_zero_iterations(unsigned len) {
+  for (unsigned i = 0; i < len; i++)
+    if (GlobalArray[i] > 0)
+      return GlobalArray[i];
+  // Previously this would have produced an overflow warning because splitting
+  // the state on the loop condition introduced an execution path where the
+  // analyzer thinks that len == 0.
+  // There are very many situations where the programmer knows that an argument
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NagyDonat wrote:

I'd like to keep the "very" here -- that's the impression that I get when I browse through lots of `ArrayBoundV2` reports (without this patch).

https://github.com/llvm/llvm-project/pull/109804