gdb: Fix issue with Clang CLI macros

Clang up to version 15 (current) adds macros that were defined in the
command line or by "other means", according to the Dwarf specification,
after the last DW_MACRO_end_file, instead of before the first
DW_MACRO_start_file, as the specification dictates.  When GDB reads the
macros after the last file is closed, the macros never end up "in scope"
and so we can't print them.  This has been submitted as a bug to Clang
developers (llvm/llvm-project#54506), and PR
macros/29034 was opened for GDB to keep track of this.

Seeing as there is no expected date for it to be fixed, add a workaround
for all current versions of Clang.  The workaround detects when
the main file would be closed and if the producer is Clang, and turns
that operation into a noop, so we keep a reference to the current_file
as those macros are read.

A test case was added to confirm the functionality, and the KFAIL for
running gdb.base/macro-source-path when using clang.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29034
Approved-By: Simon Marchi <simon.marchi@efficios.com>

gdb/dwarf2/cu.h

@@ -264,6 +264,7 @@ struct dwarf2_cu
   bool producer_is_icc : 1;
   bool producer_is_icc_lt_14 : 1;
   bool producer_is_codewarrior : 1;
+  bool producer_is_clang : 1;
 
   /* When true, the file that we're processing is known to have
      debugging info for C++ namespaces.  GCC 3.3.x did not produce

gdb/dwarf2/macro.c

@@ -445,7 +445,7 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
 			  struct dwarf2_section_info *str_section,
 			  struct dwarf2_section_info *str_offsets_section,
 			  gdb::optional<ULONGEST> str_offsets_base,
-			  htab_t include_hash)
+			  htab_t include_hash, struct dwarf2_cu *cu)
 {
   struct objfile *objfile = per_objfile->objfile;
   enum dwarf_macro_record_type macinfo_type;
@@ -672,6 +672,17 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
 	  if (! current_file)
 	    complaint (_("macro debug info has an unmatched "
 			 "`close_file' directive"));
+	  else if (current_file->included_by == nullptr
+		   && producer_is_clang (cu))
+	    {
+	      /* Clang, until the current version, misplaces some macro
+		 definitions - such as ones defined in the command line,
+		 putting them after the last DW_MACRO_end_file instead of
+		 before the first DW_MACRO_start_file.  Since at the time
+		 of writing there is no clang version with this bug fixed,
+		 we check for any clang producer.  This should be changed
+		 to producer_is_clang_lt_XX when possible. */
+	    }
 	  else
 	    {
 	      current_file = current_file->included_by;
@@ -751,7 +762,7 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
 					  current_file, lh, section,
 					  section_is_gnu, is_dwz, offset_size,
 					  str_section, str_offsets_section,
-					  str_offsets_base, include_hash);
+					  str_offsets_base, include_hash, cu);
 
 		htab_remove_elt (include_hash, (void *) new_mac_ptr);
 	      }
@@ -795,7 +806,7 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
 		     unsigned int offset, struct dwarf2_section_info *str_section,
 		     struct dwarf2_section_info *str_offsets_section,
 		     gdb::optional<ULONGEST> str_offsets_base,
-		     int section_is_gnu)
+		     int section_is_gnu, struct dwarf2_cu *cu)
 {
   bfd *abfd;
   const gdb_byte *mac_ptr, *mac_end;
@@ -956,5 +967,5 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
   dwarf_decode_macro_bytes (per_objfile, builder, abfd, mac_ptr, mac_end,
 			    current_file, lh, section, section_is_gnu, 0,
 			    offset_size, str_section, str_offsets_section,
-			    str_offsets_base, include_hash.get ());
+			    str_offsets_base, include_hash.get (), cu);
 }

gdb/dwarf2/macro.h

@@ -31,6 +31,6 @@ extern void dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
 				 dwarf2_section_info *str_section,
 				 dwarf2_section_info *str_offsets_section,
 				 gdb::optional<ULONGEST> str_offsets_base,
-				 int section_is_gnu);
+				 int section_is_gnu, struct dwarf2_cu *cu);
 
 #endif /* GDB_DWARF2_MACRO_H */

gdb/dwarf2/read.c

@@ -9484,6 +9484,16 @@ producer_is_gcc_lt_4_3 (struct dwarf2_cu *cu)
   return cu->producer_is_gcc_lt_4_3;
 }
 
+/* See dwarf2/read.h.  */
+bool
+producer_is_clang (struct dwarf2_cu *cu)
+{
+  if (!cu->checked_producer)
+    check_producer (cu);
+
+  return cu->producer_is_clang;
+}
+
 static file_and_directory &
 find_file_and_directory (struct die_info *die, struct dwarf2_cu *cu)
 {
@@ -13342,6 +13352,8 @@ check_producer (struct dwarf2_cu *cu)
     }
   else if (startswith (cu->producer, "CodeWarrior S12/L-ISA"))
     cu->producer_is_codewarrior = true;
+  else if (producer_is_clang (cu->producer, &major, &minor))
+    cu->producer_is_clang = true;
   else
     {
       /* For other non-GCC compilers, expect their behavior is DWARF version
@@ -23366,7 +23378,7 @@ dwarf_decode_macros (struct dwarf2_cu *cu, unsigned int offset,
 
   dwarf_decode_macros (per_objfile, builder, section, lh,
 		       offset_size, offset, str_section, str_offsets_section,
-		       str_offsets_base, section_is_gnu);
+		       str_offsets_base, section_is_gnu, cu);
 }
 
 /* Return the .debug_loc section to use for CU.

gdb/dwarf2/read.h

@@ -761,4 +761,7 @@ extern void dwarf2_get_section_info (struct objfile *,
 				     asection **, const gdb_byte **,
 				     bfd_size_type *);
 
+/* Return true if the producer of the inferior is clang.  */
+extern bool producer_is_clang (struct dwarf2_cu *cu);
+
 #endif /* DWARF2READ_H */

gdb/producer.c

@@ -127,6 +127,30 @@ producer_is_llvm (const char *producer)
 				 || startswith (producer, " F90 Flang ")));
 }
 
+/* See producer.h.  */
+
+bool
+producer_is_clang (const char *producer, int *major, int *minor)
+{
+  if (producer != nullptr && startswith (producer, "clang version "))
+    {
+      int maj, min;
+      if (major == nullptr)
+	major = &maj;
+      if (minor == nullptr)
+	minor = &min;
+
+      /* The full producer string will look something like
+	 "clang version XX.X.X ..."
+	 So we can safely ignore all characters before the first digit.  */
+      const char *cs = producer + strlen ("clang version ");
+
+      if (sscanf (cs, "%d.%d", major, minor) == 2)
+	return true;
+    }
+  return false;
+}
+
 #if defined GDB_SELF_TEST
 namespace selftests {
 namespace producer {

gdb/producer.h

@@ -41,4 +41,8 @@ extern bool producer_is_icc (const char *producer, int *major, int *minor);
    false otherwise.*/
 extern bool producer_is_llvm (const char *producer);
 
+/* Returns true if the given PRODUCER string is clang, false otherwise.
+   Sets MAJOR and MINOR accordingly, if not NULL.  */
+extern bool producer_is_clang (const char *producer, int *major, int *minor);
+
 #endif

gdb/testsuite/gdb.base/macro-source-path.exp

@@ -62,11 +62,6 @@ proc test { src name } {
 	}
 
 	# Print the macro that is defined on the command-line.
-	if { [test_compiler_info "clang-*"] } {
-	    # This is really a clang bug, it puts the macros defined on the command
-	    # line after the main source file, in the macro table.
-	    setup_kfail "gdb/29034" "*-*-*"
-	}
 	gdb_test "print ONE" " = 1"
 
 	# Print the macro that is defined in the main file.

gdb/testsuite/gdb.dwarf2/clang-cli-macro.c

@@ -0,0 +1,20 @@
+/* Copyright 2022 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+int
+main (void)
+{
+  asm ("main_label: .globl main_label");
+}

gdb/testsuite/gdb.dwarf2/clang-cli-macro.exp

@@ -0,0 +1,98 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Clang has this bug where it puts the macros defined on the command-line
+# after the main file portion (see PR 29034 and
+# https://github.com/llvm/llvm-project/issues/54506 )
+# Test that GDB is still able to print macros in clang versions that
+# have this bug.
+
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    return 0
+}
+if {![test_compiler_info gcc-*-*]} {
+    untested "dwarf assembler needs GCC"
+}
+
+standard_testfile .c .S
+
+lassign [function_range main $srcdir/$subdir/$srcfile] \
+    main_start main_len
+
+set asm_file [standard_output_file $srcfile2]
+
+Dwarf::assemble $asm_file {
+    declare_labels L cu_macros
+
+    cu {} {
+	DW_TAG_compile_unit {
+	    {DW_AT_producer "clang version 15.0.0"}
+	    {DW_AT_language @DW_LANG_C11}
+	    {DW_AT_name $::srcfile}
+	    {DW_AT_macros $cu_macros DW_FORM_sec_offset}
+	    {DW_AT_stmt_list $L DW_FORM_sec_offset}
+	} {
+	    declare_labels int_type
+
+	    int_type: DW_TAG_base_type {
+		{DW_AT_byte_size 4 DW_FORM_sdata}
+		{DW_AT_encoding  @DW_ATE_signed}
+		{DW_AT_name int}
+	    }
+	    DW_TAG_subprogram {
+		{MACRO_AT_func {main}}
+		{type :$int_type}
+	    }
+	}
+    }
+    lines {version 2} L {
+	file_name $::srcfile 1
+	program {
+	    DW_LNE_set_address $::main_start
+	    line 10
+	    DW_LNS_copy
+	    DW_LNE_set_address "$::main_start + $::main_len"
+	    DW_LNE_end_sequence
+	}
+    }
+
+    # Define the .debug_macro section.
+    macro {
+	cu_macros: unit {
+	    "debug-line-offset-label" $L
+	} {
+	    start_file 0 1
+		# A macro defined at line 1 of the main file.
+		define 1 "TWO 2"
+	    end_file
+	    define 0 "ONE 1"
+	}
+    }
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile [list $srcfile $asm_file] {nodebug}]} {
+    return
+}
+
+if {![runto_main]} {
+    return
+}
+
+gdb_test "print TWO" "= 2" "print simple macro"
+gdb_test "print ONE" "= 1" "print defined from CLI"