gcda1gcno

gcda1gcno is not an official standalone file format. It refers to the pair of coverage data files produced by GCC’s code coverage instrumentation: files with the extensions .gcda and .gcno. These files are used by coverage tools such as gcov, gcovr, and lcov to compute and report which parts of a program were executed during tests.

Generation and purpose: The compiler emits .gcno files when you build with coverage instrumentation (for example using -fprofile-arcs -ftest-coverage or the shorthand -coverage). When the instrumented program runs, it writes .gcda files containing runtime counters. The .gcno file stores the program’s static coverage graph, including information about basic blocks and control-flow arcs, while the .gcda file stores the dynamic data collected during execution.

Naming and location: Both files share the same base name as the source or object file and are placed in the same directory. For example, a source file foo.c may produce foo.gcno during compilation and, after a test run, foo.gcda in the same directory. They accompany the corresponding object file (or end up in the build output directory).

Usage and reporting: To generate a report, run a coverage tool such as gcov on the relevant source or object files. gcovr and lcov can also generate consolidated reports across multiple files and test runs by reading the .gcno and .gcda data. If tests are run multiple times, tools can merge or aggregate the results to provide a cumulative coverage view.

Notes: There is no standard single file named "gcda1gcno"; the conventional files are <name>.gcno and <name>.gcda. Coverage data is GCC-specific, and other toolchains may use different formats or workflows.