[binutils-gdb] gdb: Extend the comments in c-exp.y

[Andrew Burgess <aburgess at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b6c95c0cc5bd60e2de86d611120bf6191f99860a

commit b6c95c0cc5bd60e2de86d611120bf6191f99860a
Author: Andrew Burgess <andrew.burgess@embecosm.com>
Date:   Mon Dec 17 11:21:08 2018 +0000

    gdb: Extend the comments in c-exp.y
    
    In an attempt to fix PR gdb/13368 this commit adds some comments to
    c-exp.y which hopefully makes the type parsing code a little clearer.
    There are no code changes here, so there should be no user visible
    changes after this commit.
    
    gdb/ChangeLog:
    
    	PR gdb/13368
    	* c-exp.y (typebase): Extend the comment.
    	(ident_tokens): Likewise.

Diff:
---
 gdb/ChangeLog |  6 ++++++
 gdb/c-exp.y   | 17 +++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 21731be..ced5180 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2018-12-24  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	PR gdb/13368
+	* c-exp.y (typebase): Extend the comment.
+	(ident_tokens): Likewise.
+
 2018-12-18  Tom Tromey  <tom@tromey.com>
 
 	* dwarf2read.c (dwarf2_find_containing_comp_unit): Don't take
diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index bfc7841..447ac78 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -1224,7 +1224,17 @@ func_mod:	'(' ')'
 type	:	ptype
 	;
 
-typebase  /* Implements (approximately): (type-qualifier)* type-specifier */
+/* Implements (approximately): (type-qualifier)* type-specifier.
+
+   When type-specifier is only ever a single word, like 'float' then these
+   arrive as pre-built TYPENAME tokens thanks to the classify_name
+   function.  However, when a type-specifier can contain multiple words,
+   for example 'double' can appear as just 'double' or 'long double', and
+   similarly 'long' can appear as just 'long' or in 'long double', then
+   these type-specifiers are parsed into their own tokens in the function
+   lex_one_token and the ident_tokens array.  These separate tokens are all
+   recognised here.  */
+typebase
 	:	TYPENAME
 			{ $$ = $1.type; }
 	|	INT_KEYWORD
@@ -2323,7 +2333,10 @@ static const struct token tokentab2[] =
     {".*", DOT_STAR, BINOP_END, FLAG_CXX}
   };
 
-/* Identifier-like tokens.  */
+/* Identifier-like tokens.  Only type-specifiers than can appear in
+   multi-word type names (for example 'double' can appear in 'long
+   double') need to be listed here.  type-specifiers that are only ever
+   single word (like 'float') are handled by the classify_name function.  */
 static const struct token ident_tokens[] =
   {
     {"unsigned", UNSIGNED, OP_NULL, 0},