include-what-you-use 0.12 (new formula)

Closes #39565.

Signed-off-by: Izaak Beekman <zbeekman@gmail.com>

Aliases/iwyu

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+../Formula/include-what-you-use.rb

Formula/include-what-you-use.rb

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+class IncludeWhatYouUse < Formula
+  desc "Tool to analyze #includes in C and C++ source files"
+  homepage "https://include-what-you-use.org/"
+  url "https://include-what-you-use.org/downloads/include-what-you-use-0.12.src.tar.gz"
+  sha256 "a5892fb0abccb820c394e4e245c00ef30fc94e4ae58a048b23f94047c0816025"
+
+  depends_on "cmake" => :build
+  depends_on "llvm" # include-what-you-use 0.12 is compatible with llvm 8.0
+
+  def install
+    # We do not want to symlink clang headers into HOMEBREW_PREFIX, so install
+    # to libexec to ensure that the resource path, which is always computed
+    # relative to the location of the include-what-you-use executable and is
+    # not configurable, is also located under libexec.
+    args = std_cmake_args + %W[
+      -DCMAKE_INSTALL_PREFIX=#{libexec}
+      -DCMAKE_PREFIX_PATH=#{Formula["llvm"].opt_lib}
+    ]
+
+    mkdir "build" do
+      system "cmake", *args, ".."
+      system "make"
+      system "make", "install"
+    end
+
+    bin.write_exec_script Dir["#{libexec}/bin/*"]
+
+    # include-what-you-use needs a copy of the clang headers to be located
+    # in a specific folder under its resource path. These may need to be
+    # updated when new major versions of llvm are released, i.e., by
+    # incrementing the version of include-what-you-use or the revision of this
+    # formula. This would be indicated by include-what-you-use failing to
+    # locate stddef.h when running the test block below.
+    # https://clang.llvm.org/docs/LibTooling.html#libtooling-builtin-includes
+    mkdir_p libexec/"lib/clang/#{Formula["llvm"].version}/include"
+    cp_r Dir["#{Formula["llvm"].opt_lib}/clang/#{Formula["llvm"].version}/include/*"],
+      libexec/"lib/clang/#{Formula["llvm"].version}/include"
+  end
+
+  test do
+    (testpath/"direct.h").write <<~EOS
+      #include <stddef.h>
+      size_t function() { return (size_t)0; }
+    EOS
+    (testpath/"indirect.h").write <<~EOS
+      #include "direct.h"
+    EOS
+    (testpath/"main.c").write <<~EOS
+      #include "indirect.h"
+      int main() {
+        return (int)function();
+      }
+    EOS
+    expected_output = <<~EOS
+      main.c should add these lines:
+      #include "direct.h"  // for function
+
+      main.c should remove these lines:
+      - #include "indirect.h"  // lines 1-1
+
+      The full include-list for main.c:
+      #include "direct.h"  // for function
+      ---
+    EOS
+    assert_match expected_output,
+      shell_output("#{bin}/include-what-you-use main.c 2>&1", 4)
+  end
+end