Add diagnostic for cyclic #include. (#8679)

2 files changed, 27 insertions, 8 deletions

diff --git a/source/slang/slang-diagnostic-defs.h b/source/slang/slang-diagnostic-defs.h
index d31247623..840192a50 100644
--- a/source/slang/slang-diagnostic-defs.h
+++ b/source/slang/slang-diagnostic-defs.h
@@ -383,6 +383,7 @@ DIAGNOSTIC(-1, Note, seeOpeningToken, "see opening '$0'")
 // 153xx - #include
 DIAGNOSTIC(15300, Error, includeFailed, "failed to find include file '$0'")
 DIAGNOSTIC(15301, Error, importFailed, "failed to find imported file '$0'")
+DIAGNOSTIC(15302, Error, cyclicInclude, "cyclic `#include` of file '$0'")
 DIAGNOSTIC(-1, Error, noIncludeHandlerSpecified, "no `#include` handler was specified")
 DIAGNOSTIC(
     15302,
diff --git a/source/slang/slang-preprocessor.cpp b/source/slang/slang-preprocessor.cpp
index a0e80473d..ff3e5294e 100644
--- a/source/slang/slang-preprocessor.cpp
+++ b/source/slang/slang-preprocessor.cpp
@@ -1288,6 +1288,10 @@ struct Preprocessor
     /// stop them from being included again.
     HashSet<String> pragmaOnceUniqueIdentities;
 
+    /// The unique identities of any paths that have been included already.
+    /// This is used to detect cycles in #includes.
+    HashSet<String> includedFiles;
+
     WarningStateTracker* warningStateTracker = nullptr;
 
     /// Name pool to use when creating `Name`s from strings
@@ -1316,7 +1320,7 @@ struct Preprocessor
     SourceLoc::RawValue absoluteSourceLocCounter = 0;
 
     /// Push a new input file onto the input stack of the preprocessor
-    void pushInputFile(InputFile* inputFile, SourceLoc location);
+    void pushInputFile(InputFile* inputFile, SourceLoc location, String fileIdentity);
 
     /// Pop the inner-most input file from the stack of input files
     void popInputFile();
@@ -3479,7 +3483,7 @@ static SlangResult readFile(
     return SLANG_OK;
 }
 
-void Preprocessor::pushInputFile(InputFile* inputFile, SourceLoc loc)
+void Preprocessor::pushInputFile(InputFile* inputFile, SourceLoc loc, String fileIdentity)
 {
     if (m_currentInputFile)
     {
@@ -3488,13 +3492,12 @@ void Preprocessor::pushInputFile(InputFile* inputFile, SourceLoc loc)
         absoluteSourceLocCounter += offset;
     }
 
-    {
-        SourceView* sourceView = inputFile->getLexer()->m_sourceView;
-        sourceView->setAbsoluteLocationBase(absoluteSourceLocCounter);
-    }
+    SourceView* sourceView = inputFile->getLexer()->m_sourceView;
+    sourceView->setAbsoluteLocationBase(absoluteSourceLocCounter);
 
     inputFile->m_parent = m_currentInputFile;
     m_currentInputFile = inputFile;
+    includedFiles.add(fileIdentity);
 }
 
 // Handle a `#include` directive
@@ -3600,6 +3603,17 @@ static void HandleIncludeDirective(PreprocessorDirectiveContext* context)
         sourceManager->addSourceFile(filePathInfo.uniqueIdentity, sourceFile);
     }
 
+    auto fileIdentity = sourceFile->getPathInfo().getMostUniqueIdentity();
+    if (context->m_preprocessor->includedFiles.contains(fileIdentity))
+    {
+        // This file has already been included, we should diagnose an error and return.
+        GetSink(context)->diagnose(
+            pathToken.loc,
+            Diagnostics::cyclicInclude,
+            pathToken.getContent());
+        return;
+    }
+
     // If we are running the preprocessor as part of compiling a
     // specific module, then we must keep track of the file we've
     // read as yet another file that the module will depend on.
@@ -3615,7 +3629,7 @@ static void HandleIncludeDirective(PreprocessorDirectiveContext* context)
 
     InputFile* inputFile = new InputFile(context->m_preprocessor, sourceView);
 
-    context->m_preprocessor->pushInputFile(inputFile, directiveLoc);
+    context->m_preprocessor->pushInputFile(inputFile, directiveLoc, fileIdentity);
 }
 
 static void _parseMacroOps(
@@ -4624,6 +4638,7 @@ void Preprocessor::popInputFile()
         auto lastSegment = sourceView->getLastSegment();
         absoluteSourceLocCounter +=
             SourceRange(lastSegment.begin, sourceView->getRange().end).getSize();
+        includedFiles.remove(sourceView->getSourceFile()->getPathInfo().getMostUniqueIdentity());
     }
 
     // We will update the current file to the parent of whatever
@@ -4957,7 +4972,10 @@ TokenList preprocessSource(
 
         // create an initial input stream based on the provided buffer
         InputFile* primaryInputFile = new InputFile(&preprocessor, sourceView);
-        preprocessor.pushInputFile(primaryInputFile, sourceView->getRange().begin);
+        preprocessor.pushInputFile(
+            primaryInputFile,
+            sourceView->getRange().begin,
+            file->getPathInfo().getMostUniqueIdentity());
     }
 
     TokenList tokens = ReadAllTokens(&preprocessor);