Bug 6431 – [RDMD] Modifying a library doesn't trigger a rebuild

Similar to issue 6102, but for libraries: 1. Build some program with RDMD 2. Modify a static library your program uses. 3. Run RDMD again. RDMD will use the cached executable instead of rebuilding it. I've made this a separate issue because it's more difficult to solve than issue 6102.

(In reply to comment #0) > 2. Modify a static library your program uses. I assume the library is linked in via pragma(lib, "libname")?

Ultimately, for this to work correctly all the time, rdmd would need to know where the linker will look for library files. This isn't really realistic as it depends on the linker implementation (e.g. it might consult its own configuration files or environment variables). It's possible to add some heuristics to rdmd, though, e.g. to search /usr/lib, %LIB% / $LIBRARY_PATH, and the current directory.

Commit pushed to master at https://github.com/D-Programming-Language/tools https://github.com/D-Programming-Language/tools/commit/d7d17858bd8525e1481d931b5a0fb3cf2a3aad76 rdmd: Add some heuristics for detecting updated libraries (issue 6431)

I'm marking this as fixed, as a set of heuristics has been implemented in Git master. If they don't adequately cover your use case, please open another more detailed bug report.

reopening as i just bumped on this issue rdmd build 20171126 DMD64 D Compiler v2.077.0 build_lib build_main edit bar/foo.d build_lib build_main => doesn't rebuild ./setup.sh: ## rdmd doesn't rebuild if a dependent library changes build_lib(){ dmd -of=libfoo.a -lib bar/foo.d } build_main(){ exe=./main rdmd --build-only -of$exe -Llibfoo.a --exclude=bar main.d $exe } ./main.d: import bar.foo; void main(){ fun(); } ./bar/foo.d: module bar.foo; import std.stdio; void fun(){writeln("ok4");}

also: * rdmd --makedepend doesn't mention the dependent libs (libfoo.a) * dmd -deps neither * dmd -v neither

also: when adding `pragma(lib, "foo");` in main.d: (and s/-Llibfoo.a/-lfoo -L./ to make the build succeed), the dependency on lib foo will appear in both --makedepend, -deps, -v, and the rebuild will happen. without `pragma(lib, "foo");` in main.d: the dependency is not caught even if command line mentions -Llibfoo.a or -lfoo -L. Is that desired behavior? requiring pragma(lib) seems less flexible

ok the existing behavior is definitely buggy: when the dependent library is in a directory not equal to ".", a change to that library will not trigger recompilation: ``` ./setup.sh: ## buggy behavior (correct behavior only with build_dir=.) build_dir=temp build_lib(){ mkdir -p temp dmd -of=$build_dir/libfoo.a -lib bar/foo.d } build_main(){ exe=./main rdmd -v --build-only -of$exe -L-lfoo -L-L$build_dir --exclude=bar main.d $exe } build_all(){ build_lib build_main touch $build_dir/libfoo.a build_main } ./main.d: pragma(msg, "compiling..."); import bar.foo; pragma(lib, "foo"); void main(){ fun(); } ./bar/foo.d: module bar.foo; void fun(){ import std.stdio; writeln("ok1"); } ```