Fix macOS build when building inside Homebrew environment

A brew build environment sets up a clang shim (fake clang ruby script
that sets up additional compiler flags), which passes all
brew formula dependency include paths as system include paths
(via -isystem). This also includes the Qt dependency.

Because our clang parser currently ignores system headers
(see Builder::visitLocation in clangbuilder.cpp) and
because Qt include statements inside header files would resolve
to the system header location, this would result in no Qt classes
being recognized by the API extractor, and thus fail the build.

Fix this by checking for an environment variable that brew sets
inside its build environment, to filter out the unnecessary
-isystem flags.

This way the Qt include path would be passed as a non-system include
path from CMake, and thus correctly complete the build.

Task-number: PYSIDE-731
Change-Id: I9b543eddc85270f1e8a90d9f30194b2a862e80d7
Reviewed-by: Christian Tismer <tismer@stackless.com>
Reviewed-by: Alberto Sottile <alby128@gmail.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
index 820909713..0d98999b1 100644
--- a/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
+++ b/sources/shiboken2/ApiExtractor/clangparser/compilersupport.cpp
@@ -95,6 +95,36 @@ static bool runProcess(const QString &program, const QStringList &arguments,
 
 static QByteArray frameworkPath() { return QByteArrayLiteral(" (framework directory)"); }
 
+#if defined(Q_OS_MACOS)
+static void filterHomebrewHeaderPaths(HeaderPaths &headerPaths)
+{
+    QByteArray homebrewPrefix = qgetenv("HOMEBREW_OPT");
+
+    // If HOMEBREW_OPT is found we assume that the build is happening
+    // inside a brew environment, which means we need to filter out
+    // the -isystem flags added by the brew clang shim. This is needed
+    // because brew passes the Qt include paths as system include paths
+    // and because our parser ignores system headers, Qt classes won't
+    // be found and thus compilation errors will occur.
+    if (homebrewPrefix.isEmpty())
+        return;
+
+    qCInfo(lcShiboken) << "Found HOMEBREW_OPT with value:" << homebrewPrefix
+                       << "Assuming homebrew build environment.";
+
+    HeaderPaths::iterator it = headerPaths.begin();
+    while (it != headerPaths.end()) {
+        if (it->path.startsWith(homebrewPrefix)) {
+            qCInfo(lcShiboken) << "Filtering out homebrew include path: "
+                               << it->path;
+            it = headerPaths.erase(it);
+        } else {
+            ++it;
+        }
+    }
+}
+#endif
+
 // Determine g++'s internal include paths from the output of
 // g++ -E -x c++ - -v </dev/null
 // Output looks like:
@@ -130,6 +160,10 @@ static HeaderPaths gppInternalIncludePaths(const QString &compiler)
             isIncludeDir = true;
         }
     }
+
+#if defined(Q_OS_MACOS)
+    filterHomebrewHeaderPaths(result);
+#endif
     return result;
 }
 #endif // Q_CC_MSVC