restructure rustc options relating to incr. comp.

You can now pass `-Z incremental=dir` as well as saying `-Z
query-dep-graph` if you want to enable queries for some other
purpose. Accessor functions take the place of computed boolean flags.

Author: nikomatsakis

src/librustc/session/config.rs

@@ -139,11 +139,9 @@ pub struct Options {
     pub continue_parse_after_error: bool,
     pub mir_opt_level: usize,
 
-    /// if true, build up the dep-graph
-    pub build_dep_graph: bool,
-
-    /// if true, -Z dump-dep-graph was passed to dump out the dep-graph
-    pub dump_dep_graph: bool,
+    /// if Some, enable incremental compilation, using the given
+    /// directory to store intermediate results
+    pub incremental: Option<PathBuf>,
 
     pub no_analysis: bool,
     pub debugging_opts: DebuggingOptions,
@@ -260,8 +258,7 @@ pub fn basic_options() -> Options {
         treat_err_as_bug: false,
         continue_parse_after_error: false,
         mir_opt_level: 1,
-        build_dep_graph: false,
-        dump_dep_graph: false,
+        incremental: None,
         no_analysis: false,
         debugging_opts: basic_debugging_options(),
         prints: Vec::new(),
@@ -276,6 +273,15 @@ pub fn basic_options() -> Options {
     }
 }
 
+impl Options {
+    /// True if there is a reason to build the dep graph.
+    pub fn build_dep_graph(&self) -> bool {
+        self.incremental.is_some() ||
+            self.debugging_opts.dump_dep_graph ||
+            self.debugging_opts.query_dep_graph
+    }
+}
+
 // The type of entry function, so
 // users can have their own entry
 // functions that don't start a
@@ -635,10 +641,12 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "treat all errors that occur as bugs"),
     continue_parse_after_error: bool = (false, parse_bool,
           "attempt to recover from parse errors (experimental)"),
-    incr_comp: bool = (false, parse_bool,
+    incremental: Option<String> = (None, parse_opt_string,
           "enable incremental compilation (experimental)"),
     dump_dep_graph: bool = (false, parse_bool,
           "dump the dependency graph to $RUST_DEP_GRAPH (default: /tmp/dep_graph.gv)"),
+    query_dep_graph: bool = (false, parse_bool,
+          "enable queries of the dependency graph for regression testing"),
     no_analysis: bool = (false, parse_bool,
           "parse and expand the source, but run no analysis"),
     extra_plugins: Vec<String> = (Vec::new(), parse_list,
@@ -1051,8 +1059,6 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let treat_err_as_bug = debugging_opts.treat_err_as_bug;
     let continue_parse_after_error = debugging_opts.continue_parse_after_error;
     let mir_opt_level = debugging_opts.mir_opt_level.unwrap_or(1);
-    let incremental_compilation = debugging_opts.incr_comp;
-    let dump_dep_graph = debugging_opts.dump_dep_graph;
     let no_analysis = debugging_opts.no_analysis;
 
     let mut output_types = HashMap::new();
@@ -1212,6 +1218,8 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let crate_name = matches.opt_str("crate-name");
 
+    let incremental = debugging_opts.incremental.as_ref().map(|m| PathBuf::from(m));
+
     Options {
         crate_types: crate_types,
         gc: gc,
@@ -1231,8 +1239,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         treat_err_as_bug: treat_err_as_bug,
         continue_parse_after_error: continue_parse_after_error,
         mir_opt_level: mir_opt_level,
-        build_dep_graph: incremental_compilation || dump_dep_graph,
-        dump_dep_graph: dump_dep_graph,
+        incremental: incremental,
         no_analysis: no_analysis,
         debugging_opts: debugging_opts,
         prints: prints,

src/librustc_driver/driver.rs

@@ -121,7 +121,7 @@ pub fn compile_input(sess: &Session,
         let expanded_crate = assign_node_ids(sess, expanded_crate);
         // Lower ast -> hir.
         let lcx = LoweringContext::new(sess, Some(&expanded_crate));
-        let dep_graph = DepGraph::new(sess.opts.build_dep_graph);
+        let dep_graph = DepGraph::new(sess.opts.build_dep_graph());
         let mut hir_forest = time(sess.time_passes(),
                                   "lowering ast -> hir",
                                   || hir_map::Forest::new(lower_crate(&lcx, &expanded_crate),

src/test/compile-fail/dep-graph-assoc-type-trans.rs

@@ -11,7 +11,7 @@
 // Test that when a trait impl changes, fns whose body uses that trait
 // must also be recompiled.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(warnings)]

src/test/compile-fail/dep-graph-caller-callee.rs

@@ -11,7 +11,7 @@
 // Test that immediate callers have to change when callee changes, but
 // not callers' callers.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(dead_code)]

src/test/compile-fail/dep-graph-struct-signature.rs

@@ -11,7 +11,7 @@
 // Test cases where a changing struct appears in the signature of fns
 // and methods.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(dead_code)]

src/test/compile-fail/dep-graph-trait-impl-two-traits-same-method.rs

@@ -11,7 +11,7 @@
 // Test that adding an impl to a trait `Foo` DOES affect functions
 // that only use `Bar` if they have methods in common.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(dead_code)]

src/test/compile-fail/dep-graph-trait-impl-two-traits.rs

@@ -11,7 +11,7 @@
 // Test that adding an impl to a trait `Foo` does not affect functions
 // that only use `Bar`, so long as they do not have methods in common.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(warnings)]

src/test/compile-fail/dep-graph-trait-impl.rs

@@ -11,7 +11,7 @@
 // Test that when a trait impl changes, fns whose body uses that trait
 // must also be recompiled.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(warnings)]

src/test/compile-fail/dep-graph-unrelated.rs

@@ -10,7 +10,7 @@
 
 // Test that two unrelated functions have no trans dependency.
 
-// compile-flags: -Z incr-comp
+// compile-flags: -Z query-dep-graph
 
 #![feature(rustc_attrs)]
 #![allow(dead_code)]

src/test/run-make/execution-engine/test.rs

@@ -239,7 +239,7 @@ fn compile_program(input: &str, sysroot: PathBuf)
 
         let krate = driver::assign_node_ids(&sess, krate);
         let lcx = LoweringContext::new(&sess, Some(&krate));
-        let dep_graph = DepGraph::new(sess.opts.build_dep_graph);
+        let dep_graph = DepGraph::new(sess.opts.build_dep_graph());
         let mut hir_forest = ast_map::Forest::new(lower_crate(&lcx, &krate), dep_graph);
         let arenas = ty::CtxtArenas::new();
         let ast_map = driver::make_map(&sess, &mut hir_forest);