#!/bin/bash 

if [[ -z "$EQUIVS" ]] {
    setglobal EQUIVS = $[ readlink -f $[dirname $0]/../frontend/c/base-type-equivs.txt]
    if [[ -z "$EQUIVS" ]] {
        echo "Error: no equivs file" !1 > !2
    }
}

# we are reading the output of nm -fposix on a -uniqtypes.o file
setglobal uniqtypes = $[ tr -s '[:blank:]' '\t' | cut -f1 | grep '^__uniqtype_]

# build a big regexp for each equivalence class, to filter out only 
# the ones that are actually used
while read equivclass {
    # grep uniqtypes for any member of this equivalence class
    setglobal big_regexp = "'^__uniqtype_([0-9a-f]{7,8})?_('"$[ echo $equivclass | sed 's/, */|/g' | tr ' ' '_]"')$"'
    setglobal matches = $[ echo $uniqtypes | egrep $big_regexp]
    # We expect at most one typecode-qualified line for each equivclass -- 
    # i.e. a single DWARF name is used consistently in the debug info.
    if [[ $( echo "$matches" | grep '^__uniqtype_[0-9a-f]{7,8}_' | wc -l ) -gt 1 ]] {
        echo "Error: expected at most one matching uniqtype for $(big_regexp); got " $matches !1 > !2
        # If this fails, it probably means that we have multiple CUs, and some of them 
        # use different DWARF names for a given base type than others do.
        # We can be more clever about tolerating this, but it gets subtle because
        # we should really check that each CU's version of a given apparently-synonymous base type 
        # is actually the same (w.r.t. size, bit-size, encoding) as the others. 
        # Otherwise we can claim it's a type-incorrect link, although that might be a bit 
        # conservative.
        exit 1
    }
    echo $matches | sed '/^$/ d' | while read matching_typesym {
        # grep-delete the matching uniq type from the equivalence class, then
        # output a linker alias option for all the others
        setglobal matching_type = $[ echo $matching_typesym | sed -r 's/^__uniqtype_([0-9a-f]{7,8})?_//]
        echo $equivclass | sed 's/, */\n/g' | tr ' ' '_' | grep -v "^$(matching_type)"'$' | while read equiv {
            setglobal synonym_typesym = $[ echo $matching_typesym | sed -r "s/^(__uniqtype_([0-9a-f]{7,8})?_).*/\1$(equiv)/] 
            echo -Wl,--defsym,$(synonym_typesym)=$(matching_typesym)
        }
    }
} < "$EQUIVS"