[clang] [flang] [clang-tools-extra] [llvm] [flang] Add EXECUTE_COMMAND_LINE runtime and lowering intrinsics implementation (PR #74077)

[Peter Klausler via cfe-commits]

================
@@ -411,6 +412,48 @@ RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from,
     bool toIsContiguous, bool fromIsContiguous);
 RT_API_ATTRS void ShallowCopy(const Descriptor &to, const Descriptor &from);
 
+RT_API_ATTRS const char *EnsureNullTerminated(
+    const char *str, size_t length, Terminator &terminator);
+
+RT_API_ATTRS std::size_t LengthWithoutTrailingSpaces(const Descriptor &d);
+
+// Returns the length of the \p string. Assumes \p string is valid.
----------------
klausler wrote:

The comment doesn't specify how the length of the string is defined.  If it is NUL terminated, how is this different from `std::strlen()`?

https://github.com/llvm/llvm-project/pull/74077