[clang] [dataflow] Parse formulas from text (PR #66424)

[via cfe-commits]

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@@ -95,4 +98,94 @@ BoolValue &Arena::makeBoolValue(const Formula &F) {
   return *It->second;
 }
 
+namespace {
+const Formula *parse(Arena &A, llvm::StringRef &In) {
+  auto EatWhitespace = [&] { In = In.ltrim(' '); };
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martinboehme wrote:

```suggestion
  auto EatWhitespace = [&] { In = In.ltrim(); };
```

I think you initially thought you shouldn't eat newlines here, but AFAICT, this isn't an issue because `parseAll()` below splits lines before it ever calls this.

Alternatively, if you really do want to eat only spaces here, I'd suggest renaming this `EatSpaces`.

https://github.com/llvm/llvm-project/pull/66424