[Lldb-commits] [lldb] [lldb] Fix compile Python f-strings to improved `@fmt` (PR #232997)

[Dave Lee via lldb-commits]

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@@ -97,9 +97,66 @@ std::string toString(const FormatterBytecode::DataStack &data) {
 
 namespace FormatterBytecode {
 
+/// Check a version 2 format string, and remove the layout and options of each
+/// replacement. The format string may contain literal text, escaped braces
+/// ("{{"), and automatically indexed replacements:
+///
+///   "{" [ "," layout ] [ ":" options ] "}"
+///
+/// Explicit indexes are not supported. Layouts and options are accepted, so
+/// that support for them can be added without changing the ABI, but they are
+/// currently ignored. The result contains only literal text, escaped braces,
+/// and "{}", so malformed format strings never reach formatv.
+static llvm::Expected<std::string> SanitizeFormatString(llvm::StringRef fmt) {
+  std::string result;
+  size_t i = 0;
+  while (i < fmt.size()) {
+    if (fmt[i] != '{') {
+      result += fmt[i++];
+      continue;
+    }
+    if (fmt.drop_front(i).starts_with("{{")) {
+      result += "{{";
+      i += 2;
+      continue;
+    }
+    size_t start = i++;
+    // Skip the layout, which ends at the options or the closing brace.
+    if (i < fmt.size() && fmt[i] == ',') {
+      ++i;
+      while (i < fmt.size() && !llvm::StringRef("{}:").contains(fmt[i]))
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kastiglione wrote:

Updated this code to no longer use an index.

https://github.com/llvm/llvm-project/pull/232997