Bug 1591493 - Clang plugin should work with distributed builds. r=andi

sccache-dist / icecream preprocess the file and then send it to a builder.

That means that the file contains #line directives or equivalents in order for
diagnostics and such to work correctly.

Unfortunately our clang-plugin build fails catastrophically if you include a
third-party header, as it doesn't account for them.

Use SourceManager::getPresumedLoc to get filenames, as it accounts for them,
unlike just getFilename.

Differential Revision: https://phabricator.services.mozilla.com/D50633

--HG--
extra : moz-landing-system : lando

build/clang-plugin/CustomMatchers.h

@@ -137,9 +137,8 @@ AST_MATCHER(BinaryOperator, isInWhitelistForNaNExpr) {
   const char *whitelist[] = {"SkScalar.h", "json_writer.cpp", "State.cpp"};
 
   SourceLocation Loc = Node.getOperatorLoc();
-  auto &SourceManager = Finder->getASTContext().getSourceManager();
-  SmallString<1024> FileName = SourceManager.getFilename(Loc);
-
+  StringRef FileName =
+      getFilename(Finder->getASTContext().getSourceManager(), Loc);
   for (auto itr = std::begin(whitelist); itr != std::end(whitelist); itr++) {
     if (llvm::sys::path::rbegin(FileName)->equals(*itr)) {
       return true;

build/clang-plugin/MozCheckAction.cpp

@@ -24,4 +24,4 @@ public:
 static FrontendPluginRegistry::Add<MozCheckAction> X("moz-check",
                                                      "check moz action");
 
-DenseMap<unsigned, bool> InThirdPartyPathCache;
+DenseMap<StringRef, bool> InThirdPartyPathCache;

build/clang-plugin/Utils.h

@@ -9,6 +9,16 @@
 #include "ThirdPartyPaths.h"
 #include "plugin.h"
 
+inline StringRef getFilename(const SourceManager &SM, SourceLocation Loc) {
+  // We use the presumed location to handle #line directives and such, so the
+  // plugin is friendly to icecc / sccache users.
+  auto PL = SM.getPresumedLoc(Loc);
+  if (PL.isValid()) {
+    return StringRef(PL.getFilename());
+  }
+  return SM.getFilename(Loc);
+}
+
 // Check if the given expression contains an assignment expression.
 // This can either take the form of a Binary Operator or a
 // Overloaded Operator Call.
@@ -181,7 +191,7 @@ inline bool isIgnoredPathForImplicitConversion(const Decl *Declaration) {
   Declaration = Declaration->getCanonicalDecl();
   SourceLocation Loc = Declaration->getLocation();
   const SourceManager &SM = Declaration->getASTContext().getSourceManager();
-  SmallString<1024> FileName = SM.getFilename(Loc);
+  SmallString<1024> FileName = getFilename(SM, Loc);
   llvm::sys::fs::make_absolute(FileName);
   llvm::sys::path::reverse_iterator Begin = llvm::sys::path::rbegin(FileName),
                                     End = llvm::sys::path::rend(FileName);
@@ -201,7 +211,7 @@ inline bool isIgnoredPathForImplicitConversion(const Decl *Declaration) {
 inline bool isIgnoredPathForSprintfLiteral(const CallExpr *Call,
                                            const SourceManager &SM) {
   SourceLocation Loc = Call->getBeginLoc();
-  SmallString<1024> FileName = SM.getFilename(Loc);
+  SmallString<1024> FileName = getFilename(SM, Loc);
   llvm::sys::fs::make_absolute(FileName);
   llvm::sys::path::reverse_iterator Begin = llvm::sys::path::rbegin(FileName),
                                     End = llvm::sys::path::rend(FileName);
@@ -362,18 +372,16 @@ inline bool isPlacementNew(const CXXNewExpr *Expression) {
   return true;
 }
 
-extern DenseMap<unsigned, bool> InThirdPartyPathCache;
+extern DenseMap<StringRef, bool> InThirdPartyPathCache;
 
 inline bool inThirdPartyPath(SourceLocation Loc, const SourceManager &SM) {
-  Loc = SM.getFileLoc(Loc);
-
-  unsigned id = SM.getFileID(Loc).getHashValue();
-  auto pair = InThirdPartyPathCache.find(id);
+  StringRef OriginalFileName = getFilename(SM, Loc);
+  auto pair = InThirdPartyPathCache.find(OriginalFileName);
   if (pair != InThirdPartyPathCache.end()) {
     return pair->second;
   }
 
-  SmallString<1024> FileName = SM.getFilename(Loc);
+  SmallString<1024> FileName = OriginalFileName;
   llvm::sys::fs::make_absolute(FileName);
 
   for (uint32_t i = 0; i < MOZ_THIRD_PARTY_PATHS_COUNT; ++i) {
@@ -397,13 +405,13 @@ inline bool inThirdPartyPath(SourceLocation Loc, const SourceManager &SM) {
 
       // We found a match!
       if (IThirdPartyB == ThirdPartyE) {
-        InThirdPartyPathCache.insert(std::make_pair(id, true));
+        InThirdPartyPathCache.insert(std::make_pair(OriginalFileName, true));
         return true;
       }
     }
   }
 
-  InThirdPartyPathCache.insert(std::make_pair(id, false));
+  InThirdPartyPathCache.insert(std::make_pair(OriginalFileName, false));
   return false;
 }
 

build/clang-plugin/tests/TestNANTestingExpr.cpp

@@ -1,3 +1,11 @@
+#line 1 "tests/SkScalar.h"
+// This checks that the whitelist accounts for #line directives and such. If you
+// remove SkScalar from the whitelist, please change the filename here instead
+// of adding expected diagnostics.
+inline int headerSays(double x) {
+  return x != x;
+}
+#line 9 "TestNANTestingExpr.cpp"
 void test(bool x);
 void foo() {
   float f, f2;