Fix debug line number info for macro expansions.

src/librustc/middle/region.rs

@@ -237,7 +237,7 @@ impl CodeExtent {
                         // (This is the special case aluded to in the
                         // doc-comment for this method)
                         let stmt_span = blk.stmts[r.first_statement_index as usize].span;
-                        Some(Span { lo: stmt_span.hi, ..blk.span })
+                        Some(Span { lo: stmt_span.hi, hi: blk.span.hi, expn_id: stmt_span.expn_id })
                     }
                 }
             }

src/librustc/session/config.rs

@@ -891,6 +891,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "force overflow checks on or off"),
     trace_macros: bool = (false, parse_bool, [UNTRACKED],
           "for every macro invocation, print its name and arguments"),
+    debug_macros: bool = (false, parse_bool, [TRACKED],
+          "emit line numbers debug info inside macros"),
     enable_nonzeroing_move_hints: bool = (false, parse_bool, [TRACKED],
           "force nonzeroing move optimization on"),
     keep_hygiene_data: bool = (false, parse_bool, [UNTRACKED],

src/librustc_llvm/ffi.rs

@@ -1796,6 +1796,11 @@ extern {
                                                Col: c_uint)
                                                -> DILexicalBlock;
 
+    pub fn LLVMRustDIBuilderCreateLexicalBlockFile(Builder: DIBuilderRef,
+                                                   Scope: DIScope,
+                                                   File: DIFile)
+                                                   -> DILexicalBlock;
+
     pub fn LLVMRustDIBuilderCreateStaticVariable(Builder: DIBuilderRef,
                                                  Context: DIScope,
                                                  Name: *const c_char,

src/librustc_trans/debuginfo/create_scope_map.rs

@@ -25,11 +25,33 @@ use syntax_pos::Pos;
 use rustc_data_structures::bitvec::BitVector;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 
+use syntax_pos::BytePos;
+
+#[derive(Clone, Copy, Debug)]
+pub struct MirDebugScope {
+    pub scope_metadata: DIScope,
+    // Start and end offsets of the file to which this DIScope belongs.
+    // These are used to quickly determine whether some span refers to the same file.
+    pub file_start_pos: BytePos,
+    pub file_end_pos: BytePos,
+}
+
+impl MirDebugScope {
+    pub fn is_valid(&self) -> bool {
+        !self.scope_metadata.is_null()
+    }
+}
+
 /// Produce DIScope DIEs for each MIR Scope which has variables defined in it.
 /// If debuginfo is disabled, the returned vector is empty.
-pub fn create_mir_scopes(fcx: &FunctionContext) -> IndexVec<VisibilityScope, DIScope> {
+pub fn create_mir_scopes(fcx: &FunctionContext) -> IndexVec<VisibilityScope, MirDebugScope> {
     let mir = fcx.mir.clone().expect("create_mir_scopes: missing MIR for fn");
-    let mut scopes = IndexVec::from_elem(ptr::null_mut(), &mir.visibility_scopes);
+    let null_scope = MirDebugScope {
+        scope_metadata: ptr::null_mut(),
+        file_start_pos: BytePos(0),
+        file_end_pos: BytePos(0)
+    };
+    let mut scopes = IndexVec::from_elem(null_scope, &mir.visibility_scopes);
 
     let fn_metadata = match fcx.debug_context {
         FunctionDebugContext::RegularContext(box ref data) => data.fn_metadata,
@@ -59,8 +81,8 @@ fn make_mir_scope(ccx: &CrateContext,
                   has_variables: &BitVector,
                   fn_metadata: DISubprogram,
                   scope: VisibilityScope,
-                  scopes: &mut IndexVec<VisibilityScope, DIScope>) {
-    if !scopes[scope].is_null() {
+                  scopes: &mut IndexVec<VisibilityScope, MirDebugScope>) {
+    if scopes[scope].is_valid() {
         return;
     }
 
@@ -70,7 +92,12 @@ fn make_mir_scope(ccx: &CrateContext,
         scopes[parent]
     } else {
         // The root is the function itself.
-        scopes[scope] = fn_metadata;
+        let loc = span_start(ccx, mir.span);
+        scopes[scope] = MirDebugScope {
+            scope_metadata: fn_metadata,
+            file_start_pos: loc.file.start_pos,
+            file_end_pos: loc.file.end_pos,
+        };
         return;
     };
 
@@ -81,20 +108,25 @@ fn make_mir_scope(ccx: &CrateContext,
         // However, we don't skip creating a nested scope if
         // our parent is the root, because we might want to
         // put arguments in the root and not have shadowing.
-        if parent_scope != fn_metadata {
+        if parent_scope.scope_metadata != fn_metadata {
             scopes[scope] = parent_scope;
             return;
         }
     }
 
     let loc = span_start(ccx, scope_data.span);
-    scopes[scope] = unsafe {
     let file_metadata = file_metadata(ccx, &loc.file.name, &loc.file.abs_path);
+    let scope_metadata = unsafe {
         llvm::LLVMRustDIBuilderCreateLexicalBlock(
             DIB(ccx),
-            parent_scope,
+            parent_scope.scope_metadata,
             file_metadata,
             loc.line as c_uint,
             loc.col.to_usize() as c_uint)
     };
+    scopes[scope] = MirDebugScope {
+        scope_metadata: scope_metadata,
+        file_start_pos: loc.file.start_pos,
+        file_end_pos: loc.file.end_pos,
+    };
 }

src/librustc_trans/debuginfo/metadata.rs

@@ -22,7 +22,7 @@ use context::SharedCrateContext;
 use session::Session;
 
 use llvm::{self, ValueRef};
-use llvm::debuginfo::{DIType, DIFile, DIScope, DIDescriptor, DICompositeType};
+use llvm::debuginfo::{DIType, DIFile, DIScope, DIDescriptor, DICompositeType, DILexicalBlock};
 
 use rustc::hir::def_id::DefId;
 use rustc::ty::subst::Substs;
@@ -1839,3 +1839,17 @@ pub fn create_global_var_metadata(cx: &CrateContext,
                                                     ptr::null_mut());
     }
 }
+
+// Creates an "extension" of an existing DIScope into another file.
+pub fn extend_scope_to_file(ccx: &CrateContext,
+                            scope_metadata: DIScope,
+                            file: &syntax_pos::FileMap)
+                            -> DILexicalBlock {
+    let file_metadata = file_metadata(ccx, &file.name, &file.abs_path);
+    unsafe {
+        llvm::LLVMRustDIBuilderCreateLexicalBlockFile(
+            DIB(ccx),
+            scope_metadata,
+            file_metadata)
+    }
+}

src/librustc_trans/debuginfo/mod.rs

@@ -53,9 +53,10 @@ pub mod metadata;
 mod create_scope_map;
 mod source_loc;
 
-pub use self::create_scope_map::create_mir_scopes;
+pub use self::create_scope_map::{create_mir_scopes, MirDebugScope};
 pub use self::source_loc::start_emitting_source_locations;
 pub use self::metadata::create_global_var_metadata;
+pub use self::metadata::extend_scope_to_file;
 
 #[allow(non_upper_case_globals)]
 const DW_TAG_auto_variable: c_uint = 0x100;

src/librustc_trans/mir/mod.rs

@@ -10,18 +10,17 @@
 
 use libc::c_uint;
 use llvm::{self, ValueRef};
-use llvm::debuginfo::DIScope;
 use rustc::ty;
 use rustc::mir::repr as mir;
 use rustc::mir::tcx::LvalueTy;
 use session::config::FullDebugInfo;
 use base;
 use common::{self, Block, BlockAndBuilder, CrateContext, FunctionContext, C_null};
-use debuginfo::{self, declare_local, DebugLoc, VariableAccess, VariableKind};
+use debuginfo::{self, declare_local, DebugLoc, VariableAccess, VariableKind, FunctionDebugContext};
 use machine;
 use type_of;
 
-use syntax_pos::DUMMY_SP;
+use syntax_pos::{DUMMY_SP, NO_EXPANSION, COMMAND_LINE_EXPN, BytePos};
 use syntax::parse::token::keywords;
 
 use std::ops::Deref;
@@ -103,12 +102,67 @@ pub struct MirContext<'bcx, 'tcx:'bcx> {
     locals: IndexVec<mir::Local, LocalRef<'tcx>>,
 
     /// Debug information for MIR scopes.
-    scopes: IndexVec<mir::VisibilityScope, DIScope>
+    scopes: IndexVec<mir::VisibilityScope, debuginfo::MirDebugScope>,
 }
 
 impl<'blk, 'tcx> MirContext<'blk, 'tcx> {
-    pub fn debug_loc(&self, source_info: mir::SourceInfo) -> DebugLoc {
-        DebugLoc::ScopeAt(self.scopes[source_info.scope], source_info.span)
+    pub fn debug_loc(&mut self, source_info: mir::SourceInfo) -> DebugLoc {
+        // Bail out if debug info emission is not enabled.
+        match self.fcx.debug_context {
+            FunctionDebugContext::DebugInfoDisabled |
+            FunctionDebugContext::FunctionWithoutDebugInfo => {
+                // Can't return DebugLoc::None here because intrinsic::trans_intrinsic_call()
+                // relies on debug location to obtain span of the call site.
+                return DebugLoc::ScopeAt(self.scopes[source_info.scope].scope_metadata,
+                                         source_info.span);
+            }
+            FunctionDebugContext::RegularContext(_) =>{}
+        }
+
+        // In order to have a good line stepping behavior in debugger, we overwrite debug
+        // locations of macro expansions with that of the outermost expansion site
+        // (unless the crate is being compiled with `-Z debug-macros`).
+        if source_info.span.expn_id == NO_EXPANSION ||
+            source_info.span.expn_id == COMMAND_LINE_EXPN ||
+            self.fcx.ccx.sess().opts.debugging_opts.debug_macros {
+
+            let scope_metadata = self.scope_metadata_for_loc(source_info.scope,
+                                                             source_info.span.lo);
+            DebugLoc::ScopeAt(scope_metadata, source_info.span)
+        } else {
+            let cm = self.fcx.ccx.sess().codemap();
+            // Walk up the macro expansion chain until we reach a non-expanded span.
+            let mut span = source_info.span;
+            while span.expn_id != NO_EXPANSION && span.expn_id != COMMAND_LINE_EXPN {
+                if let Some(callsite_span) = cm.with_expn_info(span.expn_id,
+                                                    |ei| ei.map(|ei| ei.call_site.clone())) {
+                    span = callsite_span;
+                } else {
+                    break;
+                }
+            }
+            let scope_metadata = self.scope_metadata_for_loc(source_info.scope, span.lo);
+            // Use span of the outermost call site, while keeping the original lexical scope
+            DebugLoc::ScopeAt(scope_metadata, span)
+        }
+    }
+
+    // DILocations inherit source file name from the parent DIScope.  Due to macro expansions
+    // it may so happen that the current span belongs to a different file than the DIScope
+    // corresponding to span's containing visibility scope.  If so, we need to create a DIScope
+    // "extension" into that file.
+    fn scope_metadata_for_loc(&self, scope_id: mir::VisibilityScope, pos: BytePos)
+                               -> llvm::debuginfo::DIScope {
+        let scope_metadata = self.scopes[scope_id].scope_metadata;
+        if pos < self.scopes[scope_id].file_start_pos ||
+           pos >= self.scopes[scope_id].file_end_pos {
+            let cm = self.fcx.ccx.sess().codemap();
+            debuginfo::extend_scope_to_file(self.fcx.ccx,
+                                            scope_metadata,
+                                            &cm.lookup_char_pos(pos).file)
+        } else {
+            scope_metadata
+        }
     }
 }
 
@@ -155,16 +209,38 @@ pub fn trans_mir<'blk, 'tcx: 'blk>(fcx: &'blk FunctionContext<'blk, 'tcx>) {
          analyze::cleanup_kinds(bcx, &mir))
     });
 
+    // Allocate a `Block` for every basic block
+    let block_bcxs: IndexVec<mir::BasicBlock, Block<'blk,'tcx>> =
+        mir.basic_blocks().indices().map(|bb| {
+            if bb == mir::START_BLOCK {
+                fcx.new_block("start")
+            } else {
+                fcx.new_block(&format!("{:?}", bb))
+            }
+        }).collect();
+
     // Compute debuginfo scopes from MIR scopes.
     let scopes = debuginfo::create_mir_scopes(fcx);
 
+    let mut mircx = MirContext {
+        mir: mir.clone(),
+        fcx: fcx,
+        llpersonalityslot: None,
+        blocks: block_bcxs,
+        unreachable_block: None,
+        cleanup_kinds: cleanup_kinds,
+        landing_pads: IndexVec::from_elem(None, mir.basic_blocks()),
+        scopes: scopes,
+        locals: IndexVec::new(),
+    };
+
     // Allocate variable and temp allocas
-    let locals = {
-        let args = arg_local_refs(&bcx, &mir, &scopes, &lvalue_locals);
+    mircx.locals = {
+        let args = arg_local_refs(&bcx, &mir, &mircx.scopes, &lvalue_locals);
         let vars = mir.var_decls.iter().enumerate().map(|(i, decl)| {
             let ty = bcx.monomorphize(&decl.ty);
-            let scope = scopes[decl.source_info.scope];
-            let dbg = !scope.is_null() && bcx.sess().opts.debuginfo == FullDebugInfo;
+            let debug_scope = mircx.scopes[decl.source_info.scope];
+            let dbg = debug_scope.is_valid() && bcx.sess().opts.debuginfo == FullDebugInfo;
 
             let local = mir.local_index(&mir::Lvalue::Var(mir::Var::new(i))).unwrap();
             if !lvalue_locals.contains(local.index()) && !dbg {
@@ -173,11 +249,16 @@ pub fn trans_mir<'blk, 'tcx: 'blk>(fcx: &'blk FunctionContext<'blk, 'tcx>) {
 
             let lvalue = LvalueRef::alloca(&bcx, ty, &decl.name.as_str());
             if dbg {
-                bcx.with_block(|bcx| {
-                    declare_local(bcx, decl.name, ty, scope,
-                                VariableAccess::DirectVariable { alloca: lvalue.llval },
-                                VariableKind::LocalVariable, decl.source_info.span);
-                });
+                let dbg_loc = mircx.debug_loc(decl.source_info);
+                if let DebugLoc::ScopeAt(scope, span) = dbg_loc {
+                    bcx.with_block(|bcx| {
+                        declare_local(bcx, decl.name, ty, scope,
+                                    VariableAccess::DirectVariable { alloca: lvalue.llval },
+                                    VariableKind::LocalVariable, span);
+                    });
+                } else {
+                    panic!("Unexpected");
+                }
             }
             LocalRef::Lvalue(lvalue)
         });
@@ -203,37 +284,15 @@ pub fn trans_mir<'blk, 'tcx: 'blk>(fcx: &'blk FunctionContext<'blk, 'tcx>) {
         })).collect()
     };
 
-    // Allocate a `Block` for every basic block
-    let block_bcxs: IndexVec<mir::BasicBlock, Block<'blk,'tcx>> =
-        mir.basic_blocks().indices().map(|bb| {
-            if bb == mir::START_BLOCK {
-                fcx.new_block("start")
-            } else {
-                fcx.new_block(&format!("{:?}", bb))
-            }
-        }).collect();
-
     // Branch to the START block
-    let start_bcx = block_bcxs[mir::START_BLOCK];
+    let start_bcx = mircx.blocks[mir::START_BLOCK];
     bcx.br(start_bcx.llbb);
 
     // Up until here, IR instructions for this function have explicitly not been annotated with
     // source code location, so we don't step into call setup code. From here on, source location
     // emitting should be enabled.
     debuginfo::start_emitting_source_locations(fcx);
 
-    let mut mircx = MirContext {
-        mir: mir.clone(),
-        fcx: fcx,
-        llpersonalityslot: None,
-        blocks: block_bcxs,
-        unreachable_block: None,
-        cleanup_kinds: cleanup_kinds,
-        landing_pads: IndexVec::from_elem(None, mir.basic_blocks()),
-        locals: locals,
-        scopes: scopes
-    };
-
     let mut visited = BitVector::new(mir.basic_blocks().len());
 
     let mut rpo = traversal::reverse_postorder(&mir);
@@ -271,7 +330,7 @@ pub fn trans_mir<'blk, 'tcx: 'blk>(fcx: &'blk FunctionContext<'blk, 'tcx>) {
 /// indirect.
 fn arg_local_refs<'bcx, 'tcx>(bcx: &BlockAndBuilder<'bcx, 'tcx>,
                               mir: &mir::Mir<'tcx>,
-                              scopes: &IndexVec<mir::VisibilityScope, DIScope>,
+                              scopes: &IndexVec<mir::VisibilityScope, debuginfo::MirDebugScope>,
                               lvalue_locals: &BitVector)
                               -> Vec<LocalRef<'tcx>> {
     let fcx = bcx.fcx();
@@ -281,8 +340,8 @@ fn arg_local_refs<'bcx, 'tcx>(bcx: &BlockAndBuilder<'bcx, 'tcx>,
 
     // Get the argument scope, if it exists and if we need it.
     let arg_scope = scopes[mir::ARGUMENT_VISIBILITY_SCOPE];
-    let arg_scope = if !arg_scope.is_null() && bcx.sess().opts.debuginfo == FullDebugInfo {
-        Some(arg_scope)
+    let arg_scope = if arg_scope.is_valid() && bcx.sess().opts.debuginfo == FullDebugInfo {
+        Some(arg_scope.scope_metadata)
     } else {
         None
     };

src/rustllvm/RustWrapper.cpp

@@ -521,6 +521,15 @@ extern "C" LLVMRustMetadataRef LLVMRustDIBuilderCreateLexicalBlock(
         ));
 }
 
+extern "C" LLVMRustMetadataRef LLVMRustDIBuilderCreateLexicalBlockFile(
+    LLVMRustDIBuilderRef Builder,
+    LLVMRustMetadataRef Scope,
+    LLVMRustMetadataRef File) {
+    return wrap(Builder->createLexicalBlockFile(
+        unwrapDI<DIDescriptor>(Scope),
+        unwrapDI<DIFile>(File)));
+}
+
 extern "C" LLVMRustMetadataRef LLVMRustDIBuilderCreateStaticVariable(
     LLVMRustDIBuilderRef Builder,
     LLVMRustMetadataRef Context,