If "p4include" is in the path, treat the file as system file.

frontends/common/parser_options.cpp

@@ -494,12 +494,11 @@ void ParserOptions::dumpPass(const char *manager, unsigned seq, const char *pass
             std::unique_ptr<std::ostream> stream{openFile(fileName, true)};
             if (stream != nullptr) {
                 if (Log::verbose()) std::cerr << "Writing program to " << fileName << std::endl;
-                // FIXME: Accept path here
-                P4::ToP4 toP4(stream.get(), Log::verbose(), cstring(file));
+                P4::ToP4 toP4(stream.get(), Log::verbose(), file);
                 if (noIncludes) {
                     toP4.setnoIncludesArg(true);
                 }
-                if (node) {
+                if (node != nullptr) {
                     node->apply(toP4);
                 } else {
                     *stream << "No P4 program returned by the pass" << std::endl;

frontends/p4/frontend.cpp

@@ -104,8 +104,7 @@ class PrettyPrint : public Inspector {
     bool preorder(const IR::P4Program *program) override {
         if (!ppfile.empty()) {
             std::ostream *ppStream = openFile(ppfile, true);
-            // FIXME: ToP4 should accept PathName
-            P4::ToP4 top4(ppStream, false, cstring(inputfile));
+            P4::ToP4 top4(ppStream, false, inputfile);
             (void)program->apply(top4);
         }
         return false;  // prune

frontends/p4/toP4/toP4.cpp

@@ -17,10 +17,12 @@ limitations under the License.
 #include "toP4.h"
 
 #include <deque>
+#include <filesystem>
 #include <sstream>
 #include <string>
 
 #include "frontends/common/options.h"
+#include "frontends/common/parser_options.h"
 #include "frontends/p4/fromv1.0/v1model.h"
 #include "frontends/parsers/p4/p4parser.hpp"
 #include "ir/dump.h"
@@ -46,10 +48,12 @@ void ToP4::end_apply(const IR::Node *) {
               "inconsistent vectorSeparator");
 }
 
-// Try to guess whether a file is a "system" file
+// Try to guess whether a file is an included file.
 bool ToP4::isSystemFile(cstring file) {
     if (noIncludes) return false;
-    if (file.startsWith(p4includePath)) return true;
+    if (file != mainFile) {
+        return true;
+    }
     return false;
 }
 
@@ -148,9 +152,20 @@ void ToP4::dump(unsigned depth, const IR::Node *node, unsigned adjDepth) {
 
 bool ToP4::preorder(const IR::P4Program *program) {
     std::set<cstring> includesEmitted;
-
     bool first = true;
     dump(2);
+
+    // Try to initialize the mainFile from the program source info or the parser options.
+    if (mainFile.empty()) {
+        if (program->getSourceInfo().isValid()) {
+            mainFile = program->getSourceInfo().getSourceFile().c_str();
+        } else if (!P4CContext::get().options().file.empty()) {
+            mainFile = P4CContext::get().options().file;
+        } else {
+            ::warning("No program base file specified. ToP4 might generate incorrect includes.");
+        }
+    }
+
     for (auto a : program->objects) {
         // Check where this declaration originates
         cstring sourceFile = ifSystemFile(a);
@@ -180,8 +195,9 @@ bool ToP4::preorder(const IR::P4Program *program) {
                     builder.append(">");
                     builder.newline();
                 } else {
+                    auto relativPath = std::filesystem::relative(sourceFile.c_str(), mainFile);
                     builder.append("#include \"");
-                    builder.append(sourceFile);
+                    builder.append(relativPath);
                     builder.append("\"");
                     builder.newline();
                 }

frontends/p4/toP4/toP4.h

@@ -17,6 +17,8 @@ limitations under the License.
 #ifndef P4_TOP4_TOP4_H_
 #define P4_TOP4_TOP4_H_
 
+#include <filesystem>
+
 #include "ir/ir.h"
 #include "ir/visitor.h"
 #include "lib/sourceCodeBuilder.h"
@@ -88,9 +90,9 @@ class ToP4 : public Inspector {
     /** If this is set to non-nullptr, some declarations
         that come from libraries and models are not
         emitted. */
-    cstring mainFile;
+    std::filesystem::path mainFile;
 
-    ToP4(Util::SourceCodeBuilder &builder, bool showIR, cstring mainFile = nullptr)
+    ToP4(Util::SourceCodeBuilder &builder, bool showIR, const std::filesystem::path &mainFile = {})
         : expressionPrecedence(DBPrint::Prec_Low),
           isDeclaration(true),
           showIR(showIR),
@@ -101,7 +103,7 @@ class ToP4 : public Inspector {
         visitDagOnce = false;
         setName("ToP4");
     }
-    ToP4(std::ostream *outStream, bool showIR, cstring mainFile = nullptr)
+    ToP4(std::ostream *outStream, bool showIR, const std::filesystem::path &mainFile = {})
         : expressionPrecedence(DBPrint::Prec_Low),
           isDeclaration(true),
           showIR(showIR),