feat: Add Apple Framework header support for __has_include

Apple frameworks store headers under:
  <Pkg.framework/Headers/MyHdr.h>

This patch extends `openHeader(...)` so that
`__has_include(<Pkg/MyHdr.h>)` resolves to the framework
layout. A new test `appleFrameworkHasIncludeTest` verifies
the behavior.

Tests:
- Add dummy `Foundation.h` fixture under `testsuite/Foundation.framework/Headers/`.

Note: this applies only to `__has_include`; plain `#include`
still uses the existing lookup logic.

Co-authored-by: Jean-Christophe Fillion-Robin <jchris.fillionr@kitware.com>

Author: hjmjohnson

simplecpp.cpp

@@ -3005,6 +3005,30 @@ static std::string openHeader(std::ifstream &f, const simplecpp::DUI &dui, const
         if (!path.empty())
             return path;
     }
+
+    // a named lambda function to insert the ".framework/Headers" part for apple frameworks
+    auto get_apple_framework_relative_path= [](const std::string& appleFrameworkHeader) -> std::string {
+        // try the Framework path on apple OS, if there is a path in front
+        const size_t slashPos = appleFrameworkHeader.find('/');
+        if (slashPos == std::string::npos) {
+            return appleFrameworkHeader;
+        }
+        constexpr auto frameworkSuffix{ ".framework/Headers" };
+        return appleFrameworkHeader.substr(0, slashPos) + frameworkSuffix + appleFrameworkHeader.substr(slashPos);
+    };
+    // on Apple, try to find the header in the framework path
+    // Convert <includePath>/PKGNAME/myHeader -> <includePath>/PKGNAME.framework/Headers/myHeader
+    // Works on any platform, but only relevant when compiling against Apple SDKs.
+    const std::string appleFrameworkHeader = get_apple_framework_relative_path(header);
+    if (appleFrameworkHeader != header) {
+        for (const auto & includePath: dui.includePaths) {
+            const std::string frameworkCandidatePath = includePath + '/' + appleFrameworkHeader;
+            std::string simplePath = openHeaderDirect(f, simplecpp::simplifyPath(frameworkCandidatePath));
+            if (!simplePath.empty())
+                return simplePath;
+        }
+    }
+
     return "";
 }
 

test.cpp

@@ -2141,6 +2141,36 @@ static void circularInclude()
     ASSERT_EQUALS("", toString(outputList));
 }
 
+static void appleFrameworkHasIncludeTest()
+{
+    const char code[] =
+        "#ifdef __has_include\n"
+        "#if __has_include(<Foundation/Foundation.h>)\n"
+        "A\n"
+        "#else\n"
+        "B\n"
+        "#endif\n"
+        "#endif\n";
+
+    std::vector<std::string> files;
+    const simplecpp::TokenList rawtokens = makeTokenList(code, files, "sourcecode.cpp");
+
+    simplecpp::FileDataCache cache;
+    simplecpp::TokenList tokens2(files);
+    simplecpp::DUI dui;
+#ifdef SIMPLECPP_TEST_SOURCE_DIR
+    dui.includePaths.push_back(testSourceDir + "/testsuite");
+#else
+    dui.includePaths.push_back("./testsuite");
+#endif
+    dui.std = "c++17"; // enable __has_include
+
+    simplecpp::OutputList outputList;
+    simplecpp::preprocess(tokens2, rawtokens, files, cache, dui, &outputList);
+
+    ASSERT_EQUALS("\n\nA", tokens2.stringify()); // should take the "A" branch
+}
+
 static void multiline1()
 {
     const char code[] = "#define A \\\n"
@@ -3407,6 +3437,7 @@ int main(int argc, char **argv)
     TEST_CASE(nestedInclude);
     TEST_CASE(systemInclude);
     TEST_CASE(circularInclude);
+    TEST_CASE(appleFrameworkHasIncludeTest);
 
     TEST_CASE(nullDirective1);
     TEST_CASE(nullDirective2);

testsuite/Foundation.framework/Headers/Foundation.h

@@ -0,0 +1 @@
+// Dummy Foundation.h for appleFrameworkIncludeTest