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

[Peter Klausler via cfe-commits]

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@@ -411,6 +412,24 @@ 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 bool IsValidCharDescriptor(const Descriptor *value);
+
+RT_API_ATTRS bool IsValidIntDescriptor(const Descriptor *intVal);
+
+// Copy a null-terminated character array \p rawValue to descriptor \p value.
+// The copy starts at the given \p offset, if not present then start at 0.
+// If descriptor `errmsg` is provided, error messages will be stored to it.
+// Returns stats specified in standard.
+RT_API_ATTRS std::int32_t CopyCharsToDescriptor(const Descriptor &value,
+    const char *rawValue, std::int64_t rawValueLength,
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klausler wrote:

`rawValueLength` should probably be `std::size_t`.

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