Insert Dredd declarations at very start of file

src/libdredd/include_private/include/libdredd/mutate_visitor.h

@@ -101,11 +101,6 @@ class MutateVisitor : public clang::RecursiveASTVisitor<MutateVisitor> {
     return mutation_tree_root_;
   }
 
-  [[nodiscard]] clang::SourceLocation GetStartLocationOfFirstDeclInSourceFile()
-      const {
-    return start_location_of_first_decl_in_source_file_;
-  }
-
  private:
   // Helper class that uses the RAII pattern to support pushing a new mutation
   // tree node on to the stack of mutation tree nodes used during visitation,
@@ -170,10 +165,6 @@ class MutateVisitor : public clang::RecursiveASTVisitor<MutateVisitor> {
   const clang::CompilerInstance* compiler_instance_;
   bool optimise_mutations_;
 
-  // Records the start locat of the very first declaration in the source file,
-  // before which Dredd's prelude can be placed.
-  clang::SourceLocation start_location_of_first_decl_in_source_file_;
-
   // Tracks the nest of declarations currently being traversed. Any new Dredd
   // functions will be put before the start of the current nest, which avoids
   // e.g. putting a Dredd function inside a class or function.

src/libdredd/src/mutate_ast_consumer.cc

@@ -92,20 +92,21 @@ void MutateAstConsumer::HandleTranslationUnit(clang::ASTContext& ast_context) {
 
   *mutation_info_->add_info_for_files() = mutation_info_for_file;
 
-  const clang::SourceLocation start_location_of_first_decl_in_source_file =
-      visitor_->GetStartLocationOfFirstDeclInSourceFile();
-  assert(start_location_of_first_decl_in_source_file.isValid() &&
-         "There is at least one mutation, therefore there must be at least one "
-         "declaration.");
+  auto& source_manager = ast_context.getSourceManager();
+  const clang::SourceLocation start_of_source_file =
+      source_manager.translateLineCol(source_manager.getMainFileID(), 1, 1);
+  assert(start_of_source_file.isValid() &&
+         "There is at least one mutation, therefore the file must have some "
+         "content.");
 
   // Convert the unordered set Dredd declarations into an ordered set and add
   // them to the source file before the first declaration.
   std::set<std::string> sorted_dredd_declarations;
   sorted_dredd_declarations.insert(dredd_declarations.begin(),
                                    dredd_declarations.end());
   for (const auto& decl : sorted_dredd_declarations) {
-    const bool rewriter_result = rewriter_.InsertTextBefore(
-        start_location_of_first_decl_in_source_file, decl);
+    const bool rewriter_result =
+        rewriter_.InsertTextBefore(start_of_source_file, decl);
     (void)rewriter_result;  // Keep release-mode compilers happy.
     assert(!rewriter_result && "Rewrite failed.\n");
   }
@@ -115,8 +116,8 @@ void MutateAstConsumer::HandleTranslationUnit(clang::ASTContext& ast_context) {
           ? GetDreddPreludeCpp(initial_mutation_id)
           : GetDreddPreludeC(initial_mutation_id);
 
-  bool rewriter_result = rewriter_.InsertTextBefore(
-      visitor_->GetStartLocationOfFirstDeclInSourceFile(), dredd_prelude);
+  bool rewriter_result =
+      rewriter_.InsertTextBefore(start_of_source_file, dredd_prelude);
   (void)rewriter_result;  // Keep release-mode compilers happy.
   assert(!rewriter_result && "Rewrite failed.\n");
 
@@ -270,6 +271,7 @@ std::string MutateAstConsumer::GetRegularDreddPreludeC(
 
   std::stringstream result;
   result << "#include <inttypes.h>\n";
+  result << "#include <stdbool.h>\n";
   result << "#include <stdlib.h>\n";
   result << "#include <string.h>\n";
   result << "\n";
@@ -327,6 +329,7 @@ std::string MutateAstConsumer::GetMutantTrackingDreddPreludeC(
   std::stringstream result;
   result << "#include <inttypes.h>\n";
   result << "#include <stdatomic.h>\n";
+  result << "#include <stdbool.h>\n";
   result << "#include <stdio.h>\n";
   result << "#include <stdlib.h>\n";
   result << "\n";

src/libdredd/src/mutate_visitor.cc

@@ -35,7 +35,6 @@
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/SourceLocation.h"
-#include "clang/Basic/SourceManager.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "libdredd/mutation.h"
 #include "libdredd/mutation_remove_stmt.h"
@@ -109,23 +108,6 @@ bool MutateVisitor::TraverseDecl(clang::Decl* decl) {
     // consider it for mutation.
     return true;
   }
-  const clang::BeforeThanCompare<clang::SourceLocation> comparator(
-      compiler_instance_->getSourceManager());
-  if (start_location_of_first_decl_in_source_file_.isInvalid() ||
-      comparator(source_range_in_main_file.getBegin(),
-                 start_location_of_first_decl_in_source_file_)) {
-    // This is the first declaration wholly contained in the main file that has
-    // been encountered so far: record it so that the dredd prelude can be
-    // inserted before it.
-    //
-    // The order in which declarations appear in the source file may not exactly
-    // match the order they are visited in the AST (for example, a typedef
-    // declaration is visited after the associated type declaration, even though
-    // the 'typedef' keyword occurs first in the AST), thus this location is
-    // updated each time a declaration that appears earlier is encountered.
-    start_location_of_first_decl_in_source_file_ =
-        source_range_in_main_file.getBegin();
-  }
   if (llvm::dyn_cast<clang::StaticAssertDecl>(decl) != nullptr) {
     // It does not make sense to mutate static assertions, as (a) this will
     // very likely lead to compile-time failures due to the assertion not

test/single_file/add.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add_float.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add_float.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add_mul.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add_mul.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/add_type_aliases.c.noopt.expected

@@ -1,7 +1,5 @@
 #include <inttypes.h>
-#include <stddef.h>
-
-#include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -154,6 +152,9 @@ static int __dredd_replace_binary_operator_Add_arg1_int_arg2_int(int arg1, int a
   return arg1 + arg2;
 }
 
+#include <inttypes.h>
+#include <stddef.h>
+
 int main() {
   unsigned a;
   uint32_t b;

test/single_file/add_type_aliases.cc.noopt.expected

@@ -1,6 +1,3 @@
-#include <cinttypes>
-#include <cstddef>
-
 #include <cinttypes>
 #include <cstddef>
 #include <functional>
@@ -157,6 +154,9 @@ static int __dredd_replace_binary_operator_Add_arg1_int_arg2_int(int arg1, int a
   return arg1 + arg2;
 }
 
+#include <cinttypes>
+#include <cstddef>
+
 int main() {
   unsigned a;
   uint32_t b;

test/single_file/assign.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/assign.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/basic.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/basic.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/binary_long_long_and_long_name_clash.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/binary_operands_both_zero.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/binary_operands_both_zero.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/bitfield.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/bitfield.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/boolean_not_insertion_optimisation.c.expected

@@ -1,6 +1,5 @@
-#include <stdbool.h>
-
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -72,6 +71,8 @@ static int __dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_rhs_zero_lhs_o
   if (__dredd_enabled_mutation(local_mutation_id + 2)) return 1;
   return arg;
 }
+#include <stdbool.h>
+
 int main() {
   int x = __dredd_replace_expr_int_zero(__dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_rhs_zero_lhs_one_outer(__dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_rhs_zero_lhs_one_lhs(__dredd_replace_expr_int_one(1, 0), 5) && __dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_rhs_zero_lhs_one_rhs(__dredd_replace_expr_int_zero(0, 3), 5), 5), 8);
 }

test/single_file/boolean_not_insertion_optimisation.c.noopt.expected

@@ -1,6 +1,5 @@
-#include <stdbool.h>
-
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -68,6 +67,8 @@ static int __dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_lhs(int arg, i
   if (__dredd_enabled_mutation(local_mutation_id + 2)) return 1;
   return arg;
 }
+#include <stdbool.h>
+
 int main() {
   int x = __dredd_replace_expr_int(__dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_outer(__dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_lhs(__dredd_replace_expr_int(1, 0), 12) && __dredd_replace_binary_operator_LAnd_arg1_int_arg2_int_rhs(__dredd_replace_expr_int(0, 6), 12), 12), 15);
 }

test/single_file/comma.c.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/comma.c.noopt.expected

@@ -1,4 +1,5 @@
 #include <inttypes.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 

test/single_file/comment_at_start_of_file.cc

@@ -0,0 +1,5 @@
+// Hello
+
+int main() {
+  return 42;
+}

test/single_file/comment_at_start_of_file.cc.expected

@@ -0,0 +1,59 @@
+#include <cinttypes>
+#include <cstddef>
+#include <functional>
+#include <string>
+
+
+#ifdef _MSC_VER
+#define thread_local __declspec(thread)
+#elif __APPLE__
+#define thread_local __thread
+#endif
+
+static thread_local bool __dredd_some_mutation_enabled = true;
+static bool __dredd_enabled_mutation(int local_mutation_id) {
+  static thread_local bool initialized = false;
+  static thread_local uint64_t enabled_bitset[1];
+  if (!initialized) {
+    bool some_mutation_enabled = false;
+    const char* dredd_environment_variable = std::getenv("DREDD_ENABLED_MUTATION");
+    if (dredd_environment_variable != nullptr) {
+      std::string contents(dredd_environment_variable);
+      while (true) {
+        size_t pos = contents.find(",");
+        std::string token = (pos == std::string::npos ? contents : contents.substr(0, pos));
+        if (!token.empty()) {
+          int value = std::stoi(token);
+          int local_value = value - 0;
+          if (local_value >= 0 && local_value < 6) {
+            enabled_bitset[local_value / 64] |= (1 << (local_value % 64));
+            some_mutation_enabled = true;
+          }
+        }
+        if (pos == std::string::npos) {
+          break;
+        }
+        contents.erase(0, pos + 1);
+      }
+    }
+    initialized = true;
+    __dredd_some_mutation_enabled = some_mutation_enabled;
+  }
+  return (enabled_bitset[local_mutation_id / 64] & (1 << (local_mutation_id % 64))) != 0;
+}
+
+static int __dredd_replace_expr_int_constant(int arg, int local_mutation_id) {
+  if (!__dredd_some_mutation_enabled) return arg;
+  if (__dredd_enabled_mutation(local_mutation_id + 0)) return ~(arg);
+  if (__dredd_enabled_mutation(local_mutation_id + 1)) return -(arg);
+  if (__dredd_enabled_mutation(local_mutation_id + 2)) return 0;
+  if (__dredd_enabled_mutation(local_mutation_id + 3)) return 1;
+  if (__dredd_enabled_mutation(local_mutation_id + 4)) return -1;
+  return arg;
+}
+
+// Hello
+
+int main() {
+  if (!__dredd_enabled_mutation(5)) { return __dredd_replace_expr_int_constant(42, 0); }
+}