[PATCHv2 1/4] gdb: Extend the comments in c-exp.y

Andrew Burgess
2018-12-18T22:40:28Z

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

diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index bfc78415b22..447ac78eee1 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},
--
2.14.5