Auto merge of rust-lang#24351 - michaelwoerister:named-tuple-fields, …

…r=alexcrichton

This PR makes `rustc` emit field names for tuple fields in DWARF. Formerly there was no way of directly accessing the fields of a tuple in GDB and LLDB since there is no C/C++ equivalent to this. Now, the debugger sees the name `__{field-index}` for tuple fields. So you can type for example `some_tuple_val.__2` to get the third tuple component.
When pretty printers are used (e.g. via `rust-gdb` or `rust-lldb`) these artificial field names will not clutter tuple rendering (which was the main motivation for not doing this in the past).

Solves rust-lang#21948.

src/etc/gdb_rust_pretty_printing.py

@@ -9,6 +9,7 @@
 # except according to those terms.
 
 import gdb
+import re
 
 #===============================================================================
 # GDB Pretty Printing Module for Rust
@@ -299,12 +300,12 @@ def classify_struct(type):
     if fields[0].name == "RUST$ENUM$DISR":
         if field_count == 1:
             return STRUCT_KIND_CSTYLE_VARIANT
-        elif fields[1].name is None:
+        elif all_fields_conform_to_tuple_field_naming(fields, 1):
             return STRUCT_KIND_TUPLE_VARIANT
         else:
             return STRUCT_KIND_STRUCT_VARIANT
 
-    if fields[0].name is None:
+    if all_fields_conform_to_tuple_field_naming(fields, 0):
         if type.tag.startswith("("):
             return STRUCT_KIND_TUPLE
         else:
@@ -325,7 +326,6 @@ def first_field(val):
     for field in val.type.fields():
         return field
 
-
 def get_field_at_index(val, index):
     i = 0
     for field in val.type.fields():
@@ -334,6 +334,12 @@ def get_field_at_index(val, index):
         i += 1
     return None
 
+def all_fields_conform_to_tuple_field_naming(fields, start_index):
+    for i in range(start_index, len(fields)):
+        if (fields[i].name is None) or (re.match(r"__\d+$", fields[i].name) is None):
+            return False
+    return True
+
 def extract_length_and_data_ptr_from_std_vec(vec_val):
     length = int(vec_val["len"])
     vec_ptr_val = vec_val["ptr"]

src/etc/lldb_rust_formatters.py

@@ -9,7 +9,7 @@
 # except according to those terms.
 
 import lldb
-
+import re
 
 def print_val(val, internal_dict):
     '''Prints the given value with Rust syntax'''
@@ -61,22 +61,22 @@ def print_struct_val_starting_from(field_start_index, val, internal_dict):
         # The only field of this struct is the enum discriminant
         return type_name
 
-    has_field_names = type_has_field_names(t)
+    is_tuple_like = type_is_tuple_like(t)
 
-    if has_field_names:
-        template = "%(type_name)s {\n%(body)s\n}"
-        separator = ", \n"
-    else:
+    if is_tuple_like:
         template = "%(type_name)s(%(body)s)"
         separator = ", "
+    else:
+        template = "%(type_name)s {\n%(body)s\n}"
+        separator = ", \n"
 
     if type_name.startswith("("):
         # this is a tuple, so don't print the type name
         type_name = ""
 
     def render_child(child_index):
         this = ""
-        if has_field_names:
+        if not is_tuple_like:
             field_name = t.GetFieldAtIndex(child_index).GetName()
             this += field_name + ": "
 
@@ -233,13 +233,15 @@ def extract_type_name(qualified_type_name):
         return qualified_type_name[index + 2:]
 
 
-def type_has_field_names(ty):
+def type_is_tuple_like(ty):
     '''Returns true of this is a type with field names (struct, struct-like enum variant)'''
-    # This may also be an enum variant where the first field doesn't have a name but the rest has
-    if ty.GetNumberOfFields() > 1:
-        return ty.GetFieldAtIndex(1).GetName() is not None
-    else:
-        return ty.GetFieldAtIndex(0).GetName() is not None
+    for field in ty.fields:
+        if field.GetName() == "RUST$ENUM$DISR":
+            # Ignore the enum discriminant field if there is one.
+            continue
+        if (field.GetName() is None) or (re.match(r"__\d+$", field.GetName()) is None):
+            return False
+    return True
 
 
 def is_vec_slice(val):

src/librustc_trans/trans/debuginfo.rs

@@ -2029,7 +2029,7 @@ impl<'tcx> StructMemberDescriptionFactory<'tcx> {
 
         self.fields.iter().enumerate().map(|(i, field)| {
             let name = if field.name == special_idents::unnamed_field.name {
-                "".to_string()
+                format!("__{}", i)
             } else {
                 token::get_name(field.name).to_string()
             };
@@ -2107,9 +2107,12 @@ struct TupleMemberDescriptionFactory<'tcx> {
 impl<'tcx> TupleMemberDescriptionFactory<'tcx> {
     fn create_member_descriptions<'a>(&self, cx: &CrateContext<'a, 'tcx>)
                                       -> Vec<MemberDescription> {
-        self.component_types.iter().map(|&component_type| {
+        self.component_types
+            .iter()
+            .enumerate()
+            .map(|(i, &component_type)| {
             MemberDescription {
-                name: "".to_string(),
+                name: format!("__{}", i),
                 llvm_type: type_of::type_of(cx, component_type),
                 type_metadata: type_metadata(cx, component_type, self.span),
                 offset: ComputedMemberOffset,
@@ -2262,7 +2265,7 @@ impl<'tcx> EnumMemberDescriptionFactory<'tcx> {
                 let sole_struct_member_description = MemberDescription {
                     name: match non_null_variant.arg_names {
                         Some(ref names) => token::get_name(names[0]).to_string(),
-                        None => "".to_string()
+                        None => "__0".to_string()
                     },
                     llvm_type: non_null_llvm_type,
                     type_metadata: non_null_type_metadata,
@@ -2432,7 +2435,13 @@ fn describe_enum_variant<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                  .map(|&name| token::get_name(name).to_string())
                  .collect()
         }
-        None => variant_info.args.iter().map(|_| "".to_string()).collect()
+        None => {
+            variant_info.args
+                        .iter()
+                        .enumerate()
+                        .map(|(i, _)| format!("__{}", i))
+                        .collect()
+        }
     };
 
     // If this is not a univariant enum, there is also the discriminant field.

src/test/debuginfo/associated-types.rs

@@ -30,7 +30,7 @@
 // gdb-command:continue
 
 // gdb-command:print arg
-// gdb-check:$5 = {4, 5}
+// gdb-check:$5 = {__0 = 4, __1 = 5}
 // gdb-command:continue
 
 // gdb-command:print a

src/test/debuginfo/borrowed-enum.rs

@@ -18,13 +18,13 @@
 // gdb-command:run
 
 // gdb-command:print *the_a_ref
-// gdb-check:$1 = {{RUST$ENUM$DISR = TheA, x = 0, y = 8970181431921507452}, {RUST$ENUM$DISR = TheA, 0, 2088533116, 2088533116}}
+// gdb-check:$1 = {{RUST$ENUM$DISR = TheA, x = 0, y = 8970181431921507452}, {RUST$ENUM$DISR = TheA, __0 = 0, __1 = 2088533116, __2 = 2088533116}}
 
 // gdb-command:print *the_b_ref
-// gdb-check:$2 = {{RUST$ENUM$DISR = TheB, x = 0, y = 1229782938247303441}, {RUST$ENUM$DISR = TheB, 0, 286331153, 286331153}}
+// gdb-check:$2 = {{RUST$ENUM$DISR = TheB, x = 0, y = 1229782938247303441}, {RUST$ENUM$DISR = TheB, __0 = 0, __1 = 286331153, __2 = 286331153}}
 
 // gdb-command:print *univariant_ref
-// gdb-check:$3 = {{4820353753753434}}
+// gdb-check:$3 = {{__0 = 4820353753753434}}
 
 
 // === LLDB TESTS ==================================================================================

src/test/debuginfo/borrowed-tuple.rs

@@ -17,13 +17,13 @@
 // gdb-command:run
 
 // gdb-command:print *stack_val_ref
-// gdb-check:$1 = {-14, -19}
+// gdb-check:$1 = {__0 = -14, __1 = -19}
 
 // gdb-command:print *ref_to_unnamed
-// gdb-check:$2 = {-15, -20}
+// gdb-check:$2 = {__0 = -15, __1 = -20}
 
 // gdb-command:print *unique_val_ref
-// gdb-check:$3 = {-17, -22}
+// gdb-check:$3 = {__0 = -17, __1 = -22}
 
 
 // === LLDB TESTS ==================================================================================

src/test/debuginfo/box.rs

@@ -19,7 +19,7 @@
 // gdb-command:print *a
 // gdb-check:$1 = 1
 // gdb-command:print *b
-// gdb-check:$2 = {2, 3.5}
+// gdb-check:$2 = {__0 = 2, __1 = 3.5}
 
 
 // === LLDB TESTS ==================================================================================

src/test/debuginfo/by-value-non-immediate-argument.rs

@@ -30,15 +30,15 @@
 // gdb-command:continue
 
 // gdb-command:print a
-// gdb-check:$5 = {7, 8, 9.5, 10.5}
+// gdb-check:$5 = {__0 = 7, __1 = 8, __2 = 9.5, __3 = 10.5}
 // gdb-command:continue
 
 // gdb-command:print a
-// gdb-check:$6 = {11.5, 12.5, 13, 14}
+// gdb-check:$6 = {__0 = 11.5, __1 = 12.5, __2 = 13, __3 = 14}
 // gdb-command:continue
 
 // gdb-command:print x
-// gdb-check:$7 = {{RUST$ENUM$DISR = Case1, x = 0, y = 8970181431921507452}, {RUST$ENUM$DISR = Case1, 0, 2088533116, 2088533116}}
+// gdb-check:$7 = {{RUST$ENUM$DISR = Case1, x = 0, y = 8970181431921507452}, {RUST$ENUM$DISR = Case1, __0 = 0, __1 = 2088533116, __2 = 2088533116}}
 // gdb-command:continue
 
 

src/test/debuginfo/by-value-self-argument-in-trait-impl.rs

@@ -25,7 +25,7 @@
 // gdb-command:continue
 
 // gdb-command:print self
-// gdb-check:$3 = {4444.5, 5555, 6666, 7777.5}
+// gdb-check:$3 = {__0 = 4444.5, __1 = 5555, __2 = 6666, __3 = 7777.5}
 // gdb-command:continue
 
 

src/test/debuginfo/c-style-enum-in-composite.rs

@@ -18,13 +18,13 @@
 // gdb-command:run
 
 // gdb-command:print tuple_interior_padding
-// gdb-check:$1 = {0, OneHundred}
+// gdb-check:$1 = {__0 = 0, __1 = OneHundred}
 
 // gdb-command:print tuple_padding_at_end
-// gdb-check:$2 = {{1, OneThousand}, 2}
+// gdb-check:$2 = {__0 = {__0 = 1, __1 = OneThousand}, __1 = 2}
 
 // gdb-command:print tuple_different_enums
-// gdb-check:$3 = {OneThousand, MountainView, OneMillion, Vienna}
+// gdb-check:$3 = {__0 = OneThousand, __1 = MountainView, __2 = OneMillion, __3 = Vienna}
 
 // gdb-command:print padded_struct
 // gdb-check:$4 = {a = 3, b = OneMillion, c = 4, d = Toronto, e = 5}
@@ -36,7 +36,7 @@
 // gdb-check:$6 = {a = OneMillion, b = MountainView, c = OneThousand, d = Toronto}
 
 // gdb-command:print struct_with_drop
-// gdb-check:$7 = {{a = OneHundred, b = Vienna}, 9}
+// gdb-check:$7 = {__0 = {a = OneHundred, b = Vienna}, __1 = 9}
 
 
 // === LLDB TESTS ==================================================================================

src/test/debuginfo/cross-crate-spans.rs

@@ -25,15 +25,15 @@ extern crate cross_crate_spans;
 // gdb-command:run
 
 // gdb-command:print result
-// gdb-check:$1 = {17, 17}
+// gdb-check:$1 = {__0 = 17, __1 = 17}
 // gdb-command:print a_variable
 // gdb-check:$2 = 123456789
 // gdb-command:print another_variable
 // gdb-check:$3 = 123456789.5
 // gdb-command:continue
 
 // gdb-command:print result
-// gdb-check:$4 = {1212, 1212}
+// gdb-check:$4 = {__0 = 1212, __1 = 1212}
 // gdb-command:print a_variable
 // gdb-check:$5 = 123456789
 // gdb-command:print another_variable

src/test/debuginfo/destructured-fn-argument.rs

@@ -33,7 +33,7 @@
 // gdb-command:print a
 // gdb-check:$6 = 5
 // gdb-command:print b
-// gdb-check:$7 = {6, 7}
+// gdb-check:$7 = {__0 = 6, __1 = 7}
 // gdb-command:continue
 
 // gdb-command:print h
@@ -95,29 +95,29 @@
 // gdb-command:continue
 
 // gdb-command:print aa
-// gdb-check:$30 = {34, 35}
+// gdb-check:$30 = {__0 = 34, __1 = 35}
 // gdb-command:continue
 
 // gdb-command:print bb
-// gdb-check:$31 = {36, 37}
+// gdb-check:$31 = {__0 = 36, __1 = 37}
 // gdb-command:continue
 
 // gdb-command:print cc
 // gdb-check:$32 = 38
 // gdb-command:continue
 
 // gdb-command:print dd
-// gdb-check:$33 = {40, 41, 42}
+// gdb-check:$33 = {__0 = 40, __1 = 41, __2 = 42}
 // gdb-command:continue
 
 // gdb-command:print *ee
-// gdb-check:$34 = {43, 44, 45}
+// gdb-check:$34 = {__0 = 43, __1 = 44, __2 = 45}
 // gdb-command:continue
 
 // gdb-command:print *ff
 // gdb-check:$35 = 46
 // gdb-command:print gg
-// gdb-check:$36 = {47, 48}
+// gdb-check:$36 = {__0 = 47, __1 = 48}
 // gdb-command:continue
 
 // gdb-command:print *hh

src/test/debuginfo/destructured-for-loop-variable.rs

@@ -77,7 +77,7 @@
 // gdb-command:continue
 
 // gdb-command:print simple_tuple_ident
-// gdb-check:$24 = {34903493, 232323}
+// gdb-check:$24 = {__0 = 34903493, __1 = 232323}
 // gdb-command:continue
 
 // === LLDB TESTS ==================================================================================

src/test/debuginfo/destructured-local.rs

@@ -31,7 +31,7 @@
 // gdb-command:print f
 // gdb-check:$6 = 5
 // gdb-command:print g
-// gdb-check:$7 = {6, 7}
+// gdb-check:$7 = {__0 = 6, __1 = 7}
 
 // gdb-command:print h
 // gdb-check:$8 = 8
@@ -85,25 +85,25 @@
 // gdb-check:$29 = 33
 
 // gdb-command:print aa
-// gdb-check:$30 = {34, 35}
+// gdb-check:$30 = {__0 = 34, __1 = 35}
 
 // gdb-command:print bb
-// gdb-check:$31 = {36, 37}
+// gdb-check:$31 = {__0 = 36, __1 = 37}
 
 // gdb-command:print cc
 // gdb-check:$32 = 38
 
 // gdb-command:print dd
-// gdb-check:$33 = {40, 41, 42}
+// gdb-check:$33 = {__0 = 40, __1 = 41, __2 = 42}
 
 // gdb-command:print *ee
-// gdb-check:$34 = {43, 44, 45}
+// gdb-check:$34 = {__0 = 43, __1 = 44, __2 = 45}
 
 // gdb-command:print *ff
 // gdb-check:$35 = 46
 
 // gdb-command:print gg
-// gdb-check:$36 = {47, 48}
+// gdb-check:$36 = {__0 = 47, __1 = 48}
 
 // gdb-command:print *hh
 // gdb-check:$37 = 50

src/test/debuginfo/generic-function.rs

@@ -21,23 +21,23 @@
 // gdb-command:print *t1
 // gdb-check:$2 = 2.5
 // gdb-command:print ret
-// gdb-check:$3 = {{1, 2.5}, {2.5, 1}}
+// gdb-check:$3 = {__0 = {__0 = 1, __1 = 2.5}, __1 = {__0 = 2.5, __1 = 1}}
 // gdb-command:continue
 
 // gdb-command:print *t0
 // gdb-check:$4 = 3.5
 // gdb-command:print *t1
 // gdb-check:$5 = 4
 // gdb-command:print ret
-// gdb-check:$6 = {{3.5, 4}, {4, 3.5}}
+// gdb-check:$6 = {__0 = {__0 = 3.5, __1 = 4}, __1 = {__0 = 4, __1 = 3.5}}
 // gdb-command:continue
 
 // gdb-command:print *t0
 // gdb-check:$7 = 5
 // gdb-command:print *t1
 // gdb-check:$8 = {a = 6, b = 7.5}
 // gdb-command:print ret
-// gdb-check:$9 = {{5, {a = 6, b = 7.5}}, {{a = 6, b = 7.5}, 5}}
+// gdb-check:$9 = {__0 = {__0 = 5, __1 = {a = 6, b = 7.5}}, __1 = {__0 = {a = 6, b = 7.5}, __1 = 5}}
 // gdb-command:continue