[llvm] [llvm] Add a tool to check mustache compliance against the public spec (PR #142813)

[Nikita Popov via llvm-commits]

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+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Simple drivers to test the mustache spec found at:
+// https://github.com/mustache/spec
+//
+// It is used to verify that the current implementation conforms to the spec.
+// Simply download the spec and pass the test JSON files to the driver. Each
+// spec file should have a list of tests for compliance with the spec. These
+// are loaded as test cases, and rendered with our Mustache implementation,
+// which is then compared against the expected output from the spec.
+//
+// The current implementation only supports non-optional parts of the spec, so
+// we do not expect any of the dynamic-names, inheritance, or lambda tests to
+// pass. Additionally, Triple Mustache is not supported. Unsupported tests are
+// marked as XFail and are removed from the XFail list as they are fixed.
+//
+// Usage:
+//  llvm-test-mustache-spec path/to/test/file.json path/to/test/file2.json ...
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringSet.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Mustache.h"
+#include "llvm/Support/Path.h"
+#include <string>
+
+using namespace llvm;
+using namespace llvm::json;
+using namespace llvm::mustache;
+
+#define DEBUG_TYPE "llvm-test-mustache-spec"
+
+static cl::OptionCategory Cat("llvm-test-mustache-spec Options");
+
+static cl::list<std::string>
+    InputFiles(cl::Positional, cl::desc("<input files>"), cl::OneOrMore);
+
+static cl::opt<bool> ReportErrors("report-errors",
+                                  cl::desc("Report errors in spec tests"),
+                                  cl::cat(Cat));
+
+static ExitOnError ExitOnErr;
+
+static int NumXFail = 0;
+static int NumSuccess = 0;
+
+static const StringMap<StringSet<>> XFailTestNames = {{
+    {"delimiters.json",
+     {
+         "Pair Behavior",
+         "Special Characters",
+         "Sections",
+         "Inverted Sections",
+         "Partial Inheritence",
+         "Post-Partial Behavior",
+         "Standalone Tag",
+         "Indented Standalone Tag",
+         "Standalone Line Endings",
+         "Standalone Without Previous Line",
+         "Standalone Without Newline",
+     }},
+    {"~dynamic-names.json",
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nikic wrote:

Wondering if we should just skip the optional `~` tests entirely...

https://github.com/llvm/llvm-project/pull/142813